WS2    Flash Codes

Make: Model: Year:

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:


The “check engine light” will light up when the ignition switch is turned ON and the engine is not running. When the engine is started, the “check engine light” should go OFF. If the “check engine light” remains ON, then the Diagnosis system has detected a fault or abnormality in the system. To extract the codes the ignition switch must be switched ON. Then open the Diagnostic plug and using a “jumper wire” connect terminals “TE1 and “E1”. If the “check engine light” flashes 2 times then pauses for about 3 seconds and flashes 1 time then the system has detected a fault with the oxygen sensor. It could just be that the sensor is unplugged. The workshop shop manual has all the fault codes to check your answers with. Once the problem has been fixed check that the code has been cleared by “jumper wiring” the two terminals again. If the code has been cleared the “check engine light” will flash 1 after another which indicates Normal

2               Trouble Codes or Fault Codes

2.1          Find where the Codes are listed


The codes are listed in the workshop manual 


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
22	water temperature circuit	The voltage remains 4 volts and does not decrease
41	throttle position sensor circuit	no voltage reading as I open or close the throttle
31	vacuum sensor circuit	the voltage is high and does not move
24	intake air temperature circuit	the voltage is low and does not move

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:


The problems I found were that the ECT, TPS, Vacuum Sensor and Inatke Air temperature Sensors were disconnected. I used information from the fault code to know were to look for the problem. 

4               Repair fault

4.1          Plug back in the connector, or repair problem found

Describe what you did

I plugged all sensors back in to their connections.

5               Clear Codes 

Describe what you did to clear the codes:

To clear the codes I disconnected the battery negative cable for about 30 seconds.  

6               Recheck for codes and record codes in system now:


After disconnecting the battery negative cable the codes should be cleared from the system. To recheck for codes, "jump wire" terminals "TE1" and "E1" again and turn the ignition ON, not running. The check engine light should flash continuously 1 after the other. This indicates the system is normal. 

7               How could the faults found affect the engine performance?

           
The faults could affect the performance of the engine because the sensors that  were disconnected meant that the ECU doesn’t know how open or closed the throttle would be or what the engines coolant temperature is to adjust the correct air/fuel mixture going into the combustion chamber. Therefore when I open the throttle there is a lean mixture when there should be a rich mixture. If this engine was in car and I was driving up a hill I would have a lack of power

8               Discuss what other tests you should be doing once you have found the fault codes:


Once I have found the fault codes I should check to see if I get a voltage reading using a multi-meter and then using an Oscilloscope check the wave form patterns of the sensors and compare the results with the manufacturers specifications.