Reading Diagnostic Trouble Codes

WARNING LAMP BLINK DISPLAY
A detected system failure can sometimes come from several different failure sources; for example, a failure indicating 'discontinuity of a sensor signal' can be caused by missing wheel sensor teeth, a loose sensor, intermittent sensor connection or trigger failure.

To assist in on-board intermittent fault diagnosis, a warning lamp blink display system has been developed, using numerical codes cross-referenced to code identification charts to identify failures.

Carry out on-board fault diagnosis procedure as follows:

1. Be sure that the ignition is OFF.
2. Locate the PM4 diagnostic connector in the rear wheel arch, close to the ABS ECU.
3. Insert a short reference lead across the black lead (ground) and the brown/pink lead (trigger line to pin 23 of the ECU).
4. Turn ignition ON (position 2) and observe the warning lamp.
5. After six seconds the blink sequence of the first code begins.
6. Count the blink pulses and write down the resulting two-digit number. After a 6.5 seconds pause, the next code begins, and so on, until all the failure codes are read out and warning light remains off.
7. Remove the short lead and switch the ignition OFF.

Warning Lamp Blink Display:

Fig 1 shows a typical error code output. The first digit (tens) is represented by two flashes (blinks), the second digit (units) by one flash (blink) giving 21. After a 6.5 second pause, the next output is given; the first digit (tens) is represented by three blinks, the second digit (units) by one blink giving 31.


NOTE: The ECU is only capable of dealing with one type of fault at a time, e.g. code 21 will display but code 22 will not - instead the blink sequence will move on to the next fault type, code 31 or higher. Therefore, on completion of the required maintenance work, carry out the ECU memory erase procedure, then repeat the blink display diagnosis procedure. This will indicate any remaining or new faults in the system.


NOTE: On completion of all ABS or associated maintenance work, carry out the ECU memory erase procedure (to erase the memory, drive the car at a speed greater than 19mph (30km/h), then repeat the on-board intermittent fault diagnosis procedure (see above). This will indicate any new/persistent faults still in the system.

Single Failure Troubleshooting:

Diagnostic Trouble Codes (Part 1 Of 4):

Diagnostic Trouble Codes (Part 2 Of 4):

Diagnostic Trouble Codes (Part 3 Of 4):

Diagnostic Trouble Codes (Part 4 Of 4):