Flash Codes

Determining flash codes was the first 'on-car' task we were set. We were to use a fused link wire to short two pins on the Diagnostic plug of a 4a-fe, to place the ECU in diagnostic mode. Once that was done, we counted the times that the "Check Engine" light flashed, and converted it to a suitable number. We then checked it against a specification sheet.

 Our tutor introduced three faults into our system, which we had to diagnose and then repair. The three faults, and their codes are listed below.

Code Number                         System Affected                        Condition Described
24                                            Intake Air Temp                          Effect air fuel ratio
31                                            Vacuum Sensor                           Running real bad
41                                            Throttle Position Sensor               Bad idle

 Once the codes were discovered, we first did a visual check of the faulted circuits. In all three cases, the plugs were disconnected, but if the visual check turned out fine, we would haveto continue to test.

Once the plugs were plugged back in, i turned the ignition off then on again to clear the fault codes.