Learner workbook
- Navigate this page:
- Gather information
- Identify the fault and its cause
- Repair the fault and its cause
- Writing a diagnostic report
- Report on Job No. 1234 - Radio losing tuning pre-sets
- Other diagnostic approaches
- Benefits of this procedure
- Sketch your decision tree here.
- What if the fault is in the black box
- What is OBD 2
- How does an OBD system help with diagnostics
- Reading codes and information with a scan tool
- Proprietary and generic scan tools
- What information is available from an OBD system
- Essential features of an OBD 2 system
|
Job No. 1234 |
Date: 29/06/2010 Time: 08.45am |
Service Adviser: L. Skywalker Technician: A. Mechanic | |
|
Customer Name & Address: A. Person 16 Long Street Newburb VICTORIA 3999 Tel: 9123 4567 |
Year/ Make/ Model 2003 Daewoo Lanos 1.5 2dr Manual White VIN No: KLATF08YE3B12345xxx Engine No: A15SMS12345xxB
| ||
|
Customer Concern: Radio loses station tuning presets |
Kilometres: 165,732 | ||
|
Reg: ABC 123 | |||
|
Date & Time Promised: TBA | |||
|
Authority to Repair: J Frost | |||
|
Description of Work Carried Out | |||
|
| |||
Gather information
What questions would you (or another employee of the business) ask the customer?
Add this information onto the Job Card.
Car is seven years old.
Radio has been OK up until recently.
Once re-tuned it works fine, only loses pre-sets occasionally after engine starts.
What checks would you do?
A “look and feel” check - the radio is mounted firmly, and the connections are all secure.
After re-tuning the radio, repeated starting and stopping of the engine eventually causes the symptom to re-appear. By this time the cranking speed is noticeably slower than it was earlier.
Add this information onto the Job Card.
Description of work carried out.
Visual inspection of radio & connections OK.
Re-tuned OK.
Carried out multiple engine start-stop, symptom returned (11th try).
Note - cranking speed getting slower.
Consider the information collected so far – what does it tell you?
The radio being made up of electronic components is a part of the electrical system, and so is the starter motor – could the problems be connected?
Another test is needed to measure voltage drop at the battery during cranking.
Feedback loop
Use a multimeter to measure voltage drop at the battery during cranking. Voltage drops to 9 volts - it looks like the battery is faulty, and the low voltage is causing the radio to lose its memory during cranking.
A specific gravity test of the electrolyte is good.
A battery capacity test shows that the battery capacity is now less than half what it was when it was new, which accounts for the slower cranking speed.
A double-check of starter current draw (80A), using a good slave battery, shows that the excessive voltage drop is not being caused by the starter circuit. Alternator output measures 14.4 volts at 50 amps, which is within specifications.
Identify the fault and its cause
The technician is now confident that the faulty battery is the cause of the problem, and updates the diagnosis record:
Add this information onto the Job Card.
|
Description of work carried out Visual inspection of radio & connections OK. Re-tuned OK. Carried out multiple engine start-stop, symptom returned (11th try). Note - cranking speed getting slower. Battery connections OK. Spec Grav = 1.265 Cranking voltage = 9V. Starter draw= 80A at 11 volts using slave battery. Charging voltage 14.4V @ 50A. Battery capacity 40%. Battery is faulty |
Time on 09.35 am Time off 10.10 am |
|
Parts |
The technician has to stop here and clock off.
Someone must contact the customer and tell them that a new battery is needed, to avoid any misunderstanding later. The customer must agree to this repair, perhaps in writing.
Repairs to radio Signature……J. Frost …
Date…29/06/10 OR via Telephone:
Time received:…08.50 am Email:
Fax:
Fit new battery Signature …………...............…..
Date:…29/06/10 OR via Telephone:
Time received: 10.30 am Email:
Fax:
Add this information onto the Job Card.
Authority to Repair
Additional Work - Authority to Repair
Repair the fault and its cause
The technician can clock back on to the job and finish the repair:
Fit a new battery
Re-tune the radio to preferred stations.
Check all systems and confirm fault is fixed
Check all electrical systems for correct operation. The battery is put under load by turning on headlights, heated rear screen, air conditioning etc and at the same time repeatedly operating the starter motor.
The radio does not lose its pre-set tuning, confirming that the fault is fixed.
The last tasks for the technician are to:
Make sure that no dirty marks have been left anywhere on the car.
Park the car in the appropriate spot.
Return the driver’s seat to its original position, if it has been moved.
Add this information onto the Job Card.
|
Description of work carried out Visual inspection of radio & connections OK. Re-tuned OK. Carried out multiple engine start-stop, symptom returned (11th try). Note - cranking speed getting slower. Battery connections OK. Spec Grav = 1.265 Cranking voltage = 9V. Starter draw = 80A at 11 volts using slave battery. Charging voltage 14.4V @ 50A. Battery capacity 40%. Battery is faulty Repair Fitted new battery Re-tuned radio to customer’s stations Tested for loss of pre-sets System operation correct.
|
Time on 09.35 am Time off 10.10 am Time on 10.40 am Time off 11.30 am |
|
Parts N480ZZ battery |
Then pass the Job Card on to Reception for processing.
Reception will:
prepare the invoice for the customer
inform them that the car is ready
carry out the hand-over when the customer arrives
explain any aspects of the repair as required
taking payment.
Activity 6
Fill out the Job Card on the next page.
Use the information from the diagnosis task detailed in the section Applying these six diagnostic steps to a real problem earlier in this workbook.
My parking light isn’t working.
Find and use the VIN and engine numbers of any training vehicle in the workshop.
If a vehicle is not available, you can make these numbers up.
Make up the customer’s name and address.
STEADY EDDIE REPAIRS | |||||
|
Job No. 1235 |
Date:…………….............… Time: ………………............ |
Service Adviser: ………........………..................….. Technician: …………………….........................….. | |||
|
Customer Name & Address Tel:
|
Year/ Make/ Model ……………………………………...….............................… Reg. No. ………………………………….…………………….… VIN No. ………………….…………….……………………….… Engine No. ………………..……………………………...….…
| ||||
|
Customer Concern: |
Kilometres ……………. | ||||
|
Authority to Repair Signature: .................... ……………… Date: …../….../....... | |||||
|
Date & Time Promised: TBA | |||||
|
Description of Work Carried Out: |
Time on |
Time off | |||
|
Parts |
Cost | ||||
|
Authority to Repair ……………………………………………….. Signature: .........................................…………. Date: …../…./…….. OR via Telephone: .......................... Time received: ………………... Email: Fax: |
Additional Work- Authority to Repair ……………………………………………….. Signature: ……….................................…. Date: …../…./…….. OR via Telephone ........................... Time received: ………………... Email: Fax: | ||||
Ask your trainer to check your results before proceeding.
Trainer Signature: .............................................................. Date: .....................
This page has been left blank intentionally.
Writing a diagnostic report
When might you have to write a report on work you have done?
insurance repairs - where the insurer wants to know exactly what was done
disputes about repair work - a lawyer might want a written report about work done
careful owners - who want a written record of what was done to their vehicle
warranty work for another repairer or car dealer - eg when an interstate visitor breaks down, and your workshop carries out repairs on behalf of a third party
research work - especially if you work in the development (experimental) area of a vehicle manufacturer.
Why is it important to write a report in a standard way?
It helps to make sure that:
all the important parts of the work are covered
another person can understand what has been done
another technician can repeat your work if necessary (if it is part of a research or development project).
The following section suggests the main headings that a report might contain.
Parts of a Report
Contents
Useful for longer reports ( more than a few pages)
Helps a reader to quickly find what they want.
Introduction
Explains the reason for writing the report (why was the report requested? Who asked for it?)
Summarises the symptom and task that the report covers.
Procedure
Explains exactly what was done during the diagnosis and repair. Don’t leave out anything important
Identify any special test equipment used
A description of the conditions under which a test was done eg ambient temperature and humidity for a performance test on a vehicle’s air conditioning system.
Results of tests and investigations
Record measured test results
A report on component condition (serviceability)
Might give details of specific test procedure/s, if that could affect the test outcome eg measuring a/c pressures with or without a workshop fan in front of the condenser.
Conclusion
Explain what you have discovered/ observed/ concluded from your investigation of the problem
What you believe caused the problem
What you have done to repair it
If you haven’t solved the problem, explain why.
Recommendations
Recommend any further action you believe is needed to make sure the problem stays fixed (eg if you have just replaced an air filter element blocked with dust from unmade country roads, you might advise that the service intervals for the vehicle should be shortened from 10,000km to 5,000 km.)
An example of a report
This report was written for the job described just a little earlier where the radio kept losing its tuning pre-sets and the battery was replaced.
I’ve checked my records and the old battery was still covered by warranty. Could you give me a written report of the work done, so that I can show the supplier of the old battery that it was actually faulty? Then I can claim against the warranty.
On the next page is the technician’s report. There is no contents page, because it’s quite short:
Report on Job No. 1234 - Radio losing tuning pre-sets
Introduction
Report for Mr. A Person, owner of Daewoo Lanos, reg no. ABC 123, VIN KLATF08YE3B12345xxx.
Re: diagnosis and repair of the fault responsible for the following symptom: Radio loses tuning pre-sets intermittently.
Procedure
Vehicle delivered with radio un-tuned (pre-sets had been lost). Owner said he could re-tune the radio but the settings would be lost at irregular intervals, but only after an engine start.
Technician carried out the following checks:
Re-tuned radio without difficulty, and checked for normal operation- it performed correctly.
Visual inspection of radio and harness after re-tuning - no fault found.
Wriggle test in an attempt to re-create the problem- no fault found.
A series of engine re-starts. After the 11th re-start, the radio had lost its tuning pre-sets. Cranking speed was slower than normal, so battery volt-drop suspected as the cause of the problem.
A cranking voltage test indicated a battery problem, although a hydrometer test showed it to be fully charged.
Starter current draw was tested using a good slave battery, and alternator output was measured. Both were found to be within specifications.
A battery capacity test indicated a faulty battery. The battery was replaced with a newN480ZZ.
Results of tests and investigations
-
Operation of re-tuned radio
normal
Visual check
no faults found
Wriggle test
no faults found
Cranking voltage drop
10 volts- LOW
Starter current draw
80 amps- OK
Alternator output
14.4 volts @ 50 amps- OK
Battery specific gravity
12.65- OK
Battery capacity test
40%- faulty
Diagnosis
Inspection and testing of the systems connected with the radio showed that the radio circuit was operational, but that a faulty battery suffered excessive voltage drop on starting, leading to radio memory loss.
Repair
A new battery fixed the problem. Repetition of the start, re-start test confirmed the fault was eliminated.
Recommendations
That this vehicle be regularly serviced, with special attention to regular checks of battery electrolyte, terminal cleanliness, and mounting security to maximise battery service life.
Activity 7
Write a report on a diagnosis and repair for a ‘third party’. This could be anyone outside of the repair business - perhaps an insurance company or the manager of a vehicle fleet.
Base the report on the same repair you wrote the job card for in Activity 6 – “parking light not working”. Use the information from that section to write your report.
The report form is on the next page.
Hints
Don’t bother with a contents page- your report won’t be that long!
Use the headings A to E provided.
Write in brief points – it’s not an essay! - but include all important details.
-
STEADY EDDIE REPAIRS
Diagnostic Report on Job No. 5678
Introduction
Procedure
Results of tests and investigations
Conclusion
Recommendations
Ask your trainer to check your results before proceeding.
Trainer Signature: .............................................................. Date: .....................
Other diagnostic approaches
Branching diagnostic procedures
The diagnostic procedures discussed previously are all linear – that is, each step must be completed before you can do the next one. This approach works well for many vehicle faults, especially where the technician only has to deal with one or two systems.
When a fault occurs in a more complex system, or in a system which has connections to other systems, a branching diagnostic procedure might be used. This requires the technician to make “yes / no” or “good / bad” decisions about various components or functions of a system.
It is sometimes called a “decision tree” or a “trouble tree”.
These procedures are sometimes provided by manufacturers in their workshop manuals.
If the procedure is followed correctly, the technician will eventually diagnose the faulty component and be able to complete the repair.
Example: Part of a diagnostic procedure for checking a lubrication system
NO
YES
YES
YES
NO
NO
OK
NOT OK
Figure 6: Branching diagnostic procedure
Benefits of this procedure
The branched diagnostic procedure can speed up diagnosis.
As you gather your evidence, the procedure sets out the possible problems, and directs you to the next question or test. Decision making is reduced to simple yes / no questions.
In modern vehicles, with multiple ECUs and bus communication systems, there is a high level of interconnection between systems, and these procedures help you find your way logically through the maze.
However, the technician’s skill and knowledge is still essential for testing or evaluation of components.
CAUTION!
Be cautious when using a manufacturer’s branching diagnostic procedure. There could be errors in the process so you shouldn’t just follow it blindly.
As you work through the process, ask yourself if what you are doing is logical and in the right order, and if the specifications quoted sound sensible.
Also, they can’t take into account all the factors which are outside the system, but which could still affect it. So you must keep these in mind yourself.
Activity 8
Branched Diagnostic Procedures
Design a simple “decision tree” (branched diagnostic procedure) for the symptom described below.
Make it simple and clear so that any other technician to follow your process.
Assume that the symptom has already been confirmed.
My car has been losing coolant. I have to put in almost half a litre every week!
Vehicle: 2004 base model 4 cylinder Korean import, manual transmission.
You could start with this step:
Sketch your decision tree here.
Ask your trainer to check your results before proceeding.
Trainer Signature: .............................................................. Date: .....................
‘Black Box’ Diagnosis
Most vehicle systems now include an electronic control unit (ECU) as a master control unit. The ECU is too complex to be repaired by the average workshop, but its functions can be fairly easily understood. It is called a ‘black box’ because we know what the ECU does, but we don’t know (and don’t need to know) how it does it.
Example:
Sensors send inputs to ECU
ECU sends outputs to actuators
Figure 7: Diagram of a black box system
This diagram is a simple picture of a typical vehicle electrical or electronic system. The ECU is at the centre, with a control job to do.
The ECU receives information (‘inputs’) from a variety of sensors which are connected to the ECU by wires.
The ECU processes the inputs through its internal programming (which we don’t need to know about).
Then it sends commands (‘outputs’) to external devices (‘actuators’) to carry out specific actions. These actuators are also connected by wires to the ECU.
Sensors measure things like coolant temperature, manifold air temperature throttle position, engine rpm, crank angle and road speed.
Actuators are used to control things like alter idle speed, ignition control, fuel injectors and EGR control (Exhaust Gas Recirculation)
What if the fault is in the black box?
Most vehicle ECUs are very reliable, but occasional failures can be caused by:
dry solder joints on circuit boards
water leaks, or
“zapping” by electrical spikes such as those caused by careless welding on the vehicle.
It is more likely that the sensors or actuators will develop faults. These faults can be found by the normal diagnostic techniques described earlier. The ECU itself may be capable of testing whether there are faults in the inputs or outputs.
If all of the sensors, actuators, connections, power supplies and earths connected to the ECU are working, then the fault must be in the ECU itself.
-
CAUTION:
If all of your tests suggest that the ECU is faulty, re-check, then RE-CHECK again. ECUs can be very expensive
On-Board Diagnostics
All new cars sold in Australia from 2006 onwards must have On-Board Diagnostics (OBD). The current system is version number two and is referred to as OBD 2. All manufacturers must use the same basic system. Before this, many vehicles had some form of on-board diagnostics, but each manufacturer had a different system.
What is OBD 2?
OBD 2 is designed to self-diagnose and report when a vehicle’s emission control system fails to meet, or is likely to fail to meet, legal requirements for vehicle emissions.
OBD 2 is a universal system:
All manufacturers must use it
All manufacturers must use the same code numbers for the same emission-related faults
All cars must have the same data link connector
It must be easily accessible within about 600 mm of the driver’s seat - near the steering column, or in the centre console.
All manufacturers must use the same communication protocol to allow access to the DTCs
The emission-related codes must be accessible to any generic scan tool.
How does an OBD system help with diagnostics?
OBD systems are a valuable source of information. When a technician is gathering information early in the diagnostic procedure, a vehicle with OBD can save a lot of time by providing some of that information - how much, depends on how sophisticated the system is.
The first OBD systems often used a warning light on the instrument panel sometimes called a ‘Malfunction Indicator Light’ or a ‘Check Engine Light’.
Figure 8: Location of malfunction indicator light
This light could be made to blink or flash out a number code which could then be matched to the manufacturer’s list of possible faults. The number code is called a Diagnostic Trouble Code.
Example:
Figure 9: Coded lights
Example: Some of the Diagnostic Trouble Codes for a Holden VT 3.8 litre V6.
VT Holden V6 3.8 litre
12 No RPM signal
13 Right Hand (RH) No Oxygen Sensor Signal
14 Engine Coolant Temperature ECT - Signal Voltage Low
15 Engine Coolant Temperature ECT - Signal Voltage High
16 Engine Coolant Temperature ECT - Signal Voltage Unstable
17 PCM Error - ECT Circuit
18 EGR Flow Fault
19 Throttle Position (TP) Sensor Stuck
21 Throttle Position (TP) - Signal Voltage High
22 Throttle Position (TP) - Signal Voltage Low
23 Intake Air Temperature (IAT) - Signal Voltage High
24 No Vehicle Speed Sensor Signal - Auto Transmission
25 Intake Air Temperature (IAT) - Signal Voltage Low
26 Intake Air Temperature (IAT) - Signal Voltage Unstable
43 Knock Sensor Circuit Fault
44 Right Hand (RH) Lean Exhaust Indication
45 Right Hand (RH) Rich Exhaust Indication
46 No Reference Pulses While Cranking
47 18X Reference Signal Missing
48 Camshaft Position Signal Missing
49 Cam/Crank Signal Intermittent
63 Left Hand (LH) No Oxygen Sensor Signal
64 Left Hand (LH) Lean Exhaust Indication
65 Left Hand (LH) Rich Exhaust Indication
76 Short Term Fuel Trim (STFT) Delta High
78 Long Term Fuel Trim (LTFT) Delta High
96 AlC Pressure Sensor Fault
97 Canister Purge Circuit Fault
Some of these codes will turn on the ‘Check Engine’ light; others will not. See the workshop manual for details.
To display the VT Holden codes:
switch OFF ignition and all accessories
bridge terminals 5 and 6 of the Data Link Connector located near the steering column
The ‘Check Powertrain’ light will then flash out any DTC codes, beginning with DTC 12 (because the engine is not running).
Reading codes and information with a scan tool
A scan tool or code reader is a device which plugs into the data link connector. It can:
access the vehicle’s ECU
display the DTCs on a small screen
clear codes from the ECU’s memory.
As manufacturers developed their own particular on-board diagnostics systems, they also developed their own special scan tools to read their system. For example, a Holden dealer would use Holden’s own Tech 2 scan tool to display and clear the codes listed above.
As OBD systems developed they became too complicated to continue using the flashing method of code reading, and now the only way of accessing the codes is with a scan tool.
Figure 10: Reading codes with a scan tool
Proprietary and generic scan tools
Manufacturer’s scan tools are known as ‘proprietary’ or ‘genuine’ scan tools. They are usually only available within the dealer network. Independent automotive businesses cannot buy these tools.
Genuine scan tools
These can usually do more than just read DTCs. They may be able to:
allow the technician to see more information, such as the vehicle’s VIN
allow the technician to test the operation of output devices or actuators, such as cooling fans, fuel pumps, window motors etc.
display a direct read-out of actual live data, such as current coolant temperature, throttle position, or air conditioning pressure
upload new software to ECUs
carry out tasks such as programming replacement keys.
The trend amongst manufacturers now is to use a combined diagnostic and information system.
The vehicle is connected to a dedicated computer rather than to a hand-held scanner. The computer is better able to deal with the highly sophisticated current OBD 2 systems. It may be able to directly access a database which could include a digital workshop manual, diagnostic flow charts and service bulletins. This information could speed up diagnosis.
Generic scan tools
These are generally less capable than the genuine types but are still extremely valuable for extracting trouble codes and some live data. They are easily available from equipment suppliers.
Their capabilities can range from a basic code reader that simply displays a numeric code, to scanners which almost match the genuine scan tool in usefulness. Most generic scan tools provide adaptors (if needed) for the Data Link Connector, and either on-board software or cartridges to allow the scanner to communicate with a wide range of vehicles.
What information is available from an OBD system?
Early OBDs focussed on faults related to the powertrain (engine and transmission) and emission controls. As they became more sophisticated, the amount and type of information expanded.
The modern OBD 2 systems can:
show live or current data (the actual values right now for various components, such as air flow rate, current RPM, or ignition timing)
show ‘freeze frame’ data (the information captured by sensorsat the time the fault occurred)
show stored Diagnostic Trouble Codes
show pending Diagnostic Trouble Codes (detected during current or last driving cycle)
clear Diagnostic Trouble Codes and stored values
test results, oxygen sensor monitoring (non Controller Area Network [CAN] only)
test results, other component/system monitoring (Test results, oxygen sensor monitoring for Controller Area Network [CAN] only)
control operation of on-board components/ systems
request vehicle information.
Essential features of an OBD 2 system
Check Engine light
The system will verify a fault before turning on the light. A detected fault is stored as a pending fault. If the same fault occurs on the next two driving cycles, the light will be turned on and the fault is stored as a confirmed fault.
The light may be turned off again if that fault doesn’t happen again during the next three driving cycles.
Freeze Frame information
When a fault is first detected, the system must store at least the following information:
the fault code for the event that prompted the data to be stored
coolant temperature
engine speed
engine load
fuel pressure, if available
inlet manifold pressure, if available
fuel trim values, if available
open or closed loop operation
vehicle speed, if available.
Readiness testing
The system monitors and tests all emission-related components or systems during a specified drive cycle. The ECU reports ‘Ready’ or ‘Not Ready’ for those systems when a scan tool is connected.
Some systems are monitored continuously, such as engine misfiring and evaporative emissions. Other systems are monitored, but not continuously, such as the EGR, catalytic converter, air conditioning etc.
During these tests the system may turn various sensors and actuators on or off to see what effect is produced, and compare that effect with the expected result. Any variation outside of the programmed limits will set a diagnostic trouble code.
Diagnostic Trouble Codes
a. Mandated codes
For any emission-related system, the codes are provided by the government and must be used no matter what make the car is. The codes must be accessible by any OBD 2 scan tool.
The codes must have a letter followed by four numbers, like this: P0105. The meaning of the code is the same for all manufacturers. In this case, P0105 means ‘Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction’, no matter what make of car it is.
b. Manufacturers’ codes
For any other system, like ABS, manufacturers can make up their own DTCs and they are not obliged to give code access to non-proprietary scan tools (though many do).
How OBD 2 codes work
There are probably thousands of possible OBD 2 codes. This is the way they are created.
-
P
0
1
15
Which vehicle system triggered the code?
Is the code mandated or a manufacturer’s own code?
What sub-system is associated with the fault?
Gives more detail of the fault
P= Powertrain system
B= Body system
C= Chassis system
U= Unused, or sometimes communication faults
0 = Mandated code (emissions)1 = Enhanced OBD 2 code available for use by any vehicle maker
1 = Fuel and air metering2 = Fuel and air (injection circuit)
3 = Ignition or misfire
4 = Auxiliary emission controls
5 = Vehicle speed and idle control
6 = Transmission
Many possibilities
P0115 is a powertrain problem
P0115 is a mandated code.
P0115 is a fault which affects fuel and/or air metering
15 indicates a fault in the Coolant Temperature circuit, which would affect fuelling
Vehicle System codes
P codes- Power train means engine and transmission sub-systems.
B codes- Body control systems like lighting, air conditioning, audio etc.
C codes- Chassis control systems like ABS, ESP, active suspension, traction control etc.
Enhanced OBD 2 code - it is the manufacturer’s choice to make it available to a scan tool
Body and Chassis Codes
Examples: B0540 Speedo signal error (used by any / all manufacturers)
C0035 LHF wheel speed signal error (used by Holden)
Below is a sample list of OBD 2 ‘P’ codes:
These are just a few of the many codes possible.
P0010 A Camshaft Position Actuator Circuit (Bank 1)
P0011 A Camshaft Position - Timing Over - Advanced or System Performance (Bank 1)
P0012 A Camshaft Position - Timing Over - Retarded (Bank 1)
P0013 B Camshaft Position - Actuator Circuit (Bank 1)
P0014 B Camshaft Position - Timing Over - Advanced or System Performance (Bank 1)
P0015 B Camshaft Position - Timing Over - Retarded (Bank 1)
P0024 B Camshaft Position - Timing Over - Advanced or System Performance (Bank 2)
P0025 B Camshaft Position - Timing Over - Retarded (Bank 2)
P0026 Intake Valve Control Solenoid Circuit Range/Performance (Bank 1)
P0027 Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 1)
P0028 Intake Valve Control Solenoid Circuit Range/Performance (Bank 2)
P0029 Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 2)
P0068 MAP/MAF - Throttle Position Correlation
P0069 Manifold Absolute Pressure - Barometric Pressure Correlation
P0070 Ambient Air Temperature Sensor Circuit
P0071 Ambient Air Temperature Sensor Range/Performance
P0072 Ambient Air Temperature Sensor Circuit Low
P0073 Ambient Air Temperature Sensor Circuit High
P0074 Ambient Air Temperature Sensor Circuit Intermittent
P0095 Intake Air Temperature Sensor 2 Circuit
P0096 Intake Air Temperature Sensor 2 Circuit Range/Performance
P0097 Intake Air Temperature Sensor 2 Circuit Low
P0098 Intake Air Temperature Sensor 2 Circuit High
P0099 Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic
You can see that there is an enormous amount of information that could be available to a technician trying to diagnose a fault.
How much information you can actually get depends on which codes the manufacturer has decided to use, and whether the maker has given free access to any non- mandated, vehicle specific codes as well.
This page has been left blank intentionally.
Activity 9
Tick the correct answer/s. There may be more than one.
Question 1
When using ‘black box’ diagnosis to find a fault, the technician must:
Replace any ECUs which are not coloured black
Test no more than three of the inputs to the ECU
Test all of the sensors, actuators, power supplies and earths connected to the black box
Open the black box and probe the circuit boards with a Phillips screwdriver.
Question 2
When discussing vehicle faults, the term ‘OBD’ means:
Out Board Depth
One Bad Device
On Board Diagnostics
Own Brand Diagnostics.
Question 3
What is OBD 2?
A compulsory on-board diagnostic system for all new cars since 2006
A voluntary on-board diagnostic system for all new cars since 2006
An on-board diagnostic system accessible by any OBD 2 scan tool
An on-board diagnostic system aimed at monitoring vehicle emissions.
Question 4
The purpose of an OBD system is to:
Detect faults in vehicle systems and immobilize the vehicle until repairs are made
Detect faults in vehicle systems and alert the driver
Detect faults in vehicle systems and automatically fix the problem
Detect faults in vehicle systems and tell the technician where to look for faults.
Question 5
When a fault is detected in a vehicle system, the driver is alerted by:
An SMS message
Malfunction indicator light
A voice message through the audio system.
Question 6
An OBD 2 system should be able to:
Show current data
Show ‘freeze frame’ data
Show stored Diagnostic Trouble Codes
Clear Diagnostic Trouble Codes and stored values
Show pending Diagnostic Trouble Codes.
Question 7
A ‘pending’ OBD 2 code is one which:
Does not turn on the ‘Check Engine’ light
Is set when a fault occurs once, but doesn’t appear again
Depends on the make of vehicle
Relates only to suspension systems.
Question 8
‘Freeze frame’ data is:
The information captured by the ECU when a DTC occurred
Information that relates only to the climate control system
The data the system’s sensors were providing at the time a fault occurred
Information provided when the engine seizes.
Question 9
‘Live data’ is:
Only available if the technician is in the driver’s seat
The actual operating values for various parts of an operating system e.g. voltage
Provided only for components which have movement e.g. windscreen wipers
Available from any live electrical connection e.g. the positive battery terminal.
Question 10
What do these OBD 2 codes mean?
P0442
P0074
P0013
P0103
P0205
Ask your trainer to check your results before proceeding.
Trainer Signature: .............................................................. Date: .....................
This page has been left blank intentionally.
Activity 10
Ask your teacher to direct you to a vehicle or a system with a fault. Use any of the methods described in this workbook, OR any other method available to you to diagnose the fault in the vehicle or system.
You may use workshop manuals supplied by your teacher; textbooks; commercial information sources; service bulletins; test equipment or scan tools to help you.
Remember to check the workshop manual for any suggested diagnostic approaches.
As you work through the diagnosis, record the steps you take and the results of any tests you make. The record can be in the form of a step-by-step procedure, or it could be a ‘decision tree’.
Observe all relevant safety precautions while working.
Good luck!
Ask your trainer to check your results before proceeding.
Trainer Signature: .............................................................. Date: .....................
This page has been left blank intentionally.
Glossary
-
WORD
MEANING
abnormal
Things are NOT okay, or NOT the way they should be
abnormal event
When something happens NOT in the way it should
accurate
Correct, exact
actuators
Devices which carry out specific actions
confirm
Check that something is true
confirmed
Definite
data
Information
diagnosis
Finding the cause of a problem
efficient
Doing things well in the quickest time possible
eliminate
Get rid of
event
Something that happens
fault
Problem
faulty
Worn, broken, not working correctly
feedback loop
When you get some information from a check or test, you use it to rethink what you will do next.
‘freeze frame’ data
Information which shows exactly what data the system’s sensors were providing at the time the fault occurred
hazard
Danger
inefficient
Taking longer than necessary to do something
input
Information going into a system
live data
Information from right now, such as current coolant temperature, throttle position, or air conditioning pressure
logical
Sensible
mandated
Required by law
minimum
Least
normal
Things are okay or the way they should be
normal event
When something happens in exactly the way it should
output
Command or message going out
pending
Waiting
procedure
A logical set of steps to follow
productivity
Time spent per job
proprietary
Owned by the manufacturer
subsequent
Later
symptom
A clue that something is wrong.
systematic
Following a sensible order or system, not just any way it happens
third party
First party - the car ownerSecond party -the repair business
Third party – someone else eg an insurance company, or the manager of a vehicle fleet
valid
True
ventilation
Fresh air
warranty
Manufacturer’s promise to replace a faulty item
auto -> Unit: Automotive and Auto Body
auto -> Word Wall Chants Use these as fun ways to practice word wall words at home!
auto -> A message from Mr. Dryden
auto -> Major works data sheet
auto -> U. S. Steel Corporation, Elbert H. Gary Gary was corporate lawyer who became the U. S. Steel Corporation president in 1898. U. S. Steel was the leading steel producer at the time
auto -> Identify the choice that best completes the statement or answers the question
auto -> Historical periods to memorize
auto -> Geography handbook
auto -> It rose out of the tropical Pacific in late 1997, bearing more energy than a million Hiroshima bombs
Share with your friends:
