Warning: Be careful working around engines and exercise caution to avoid injury.
Note: The engine check light must be working.
If you have problems with the task, see you lecturer for help.
1. Flash/Blink Codes
1.1 Find a engine/vehicle that you have the workshop manual with the correct procedure and codes to diagnose the flash codes
1.2 Have your tutor create a fault in the EFI system
1.3 Using the workshop manual follow the procedure to extract the codes, explain briefly what is the procedure
Firstly, When the ignition switch is turned on, the check engine light should light up then the engine is started, the light should turn off. Secondly, If the faults are found the diagnostic plug should open and connect between TE1 and E1. Thirdly, the ignition switch is turned on, the check engine light should flash according to fault codes. If the TPS has a fault, the light will flash four times and the light will turn off for a little while. And then, the light will turn on one time for second fault code. Next, I can check the fault codes from the manufacturer specification and I also find out other problems. The fault codes should be clear, after I repair the faults. Finally, the fault codes should be rechecked. When the E1 and TE1 of diagnosis box are connected, the check engine light should continuously flash under normal conditions.
2.1 Find where the Codes are listed
2.2 Record any codes, and what system and condition they describe in the chart below (Example: might be code number 21, for Throttle Position Sensor, signal voltage too low)
Code number System affected Condition described
41 TPS No voltages(Idle normal)
33 IAC Engine idle is high
31 Vacuum Sensor The engine is turned off and rough idle
3 Visual Inspection to find fault
3.1 Do a visual inspection under the bonnet to find where the problem is. Use information from the code to know where to look for the problem and what type of problem to look for.
3.2 Describe the problem(s) you found:
Following the fault codes, I found the disconnection of some sensors, such as TPS, vacuum sensor and Idle air control sensor.
4. Repair fault
4.1 Plug back in the connector, or repair problem found
Describe what you did:
After plug back in the connector, I have checked the engine condition and retested the signal voltage of sensors. The engine have recovered with appropriate conditions.
5 Clear Codes
Describe what you did to clear the codes:
I made a disconnection of negative terminal of a battery or main fuse for 30 seconds.
6 Recheck for codes and record codes in system now:
After clear codes, E1 and TE1 of diagnosis box should be reconnected. When the ignition switch is turned on and the engine is not running, the check engine light is contantly flashing that means normal condition of the engine without any faults.
7 How could the faults found affect the engine performance?
From the faults, the engine does not run properly and has abnormal conditions with lower engine performance.
8 Discuss what other tests you should be doing once you have found the fault codes:
I can recheck the voltages of sensor's signal using a multimeter and lab scope with manufacturer specification. In addition, I can find out the fault codes easily from using scan tool diagnostics.
Some more in-depth diagnostics would be better on some of these questions
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