Reading and Clearing Diagnostic Trouble Codes

Fig. 1 ABS Diagnostic Code Display:

Fig. 1 ABS Codes:

Reading ABS Trouble Codes Follow this procedure when directed by the functional check:


1. Turn the ignition switch to the "run" position:
^ Allow the accumulator to charge (30 seconds maximum).
^ Observe the "BRAKE" and "ANTILOCK" lamps:
^ Both lamps should turn OFF within 30 seconds.
2. Turn the ignition switch to the "OFF" position:
^ Place a jumper wire between ALDL terminal "G" (or "H") and "A" (or chassis ground)
3. Turn the ignition switch to the 'run" position.
A. Observe the. "ANTILOCK" lamp:
^ If the lamp lights for four seconds and then turns OFF (and remains OFF), no trouble codes are stored.
^ If the lamp lights for four seconds and then starts flashing, one or more trouble codes are stored. Trouble codes are represented as a series of flashes of the "ANTILOCK" lamp. All trouble codes are are two digit codes and will be displayed as a series of flashes then a pause and another series of flashes. "Flash" "Flash" pause "Flash" would be a code 21. There will also be a pause between codes if multiple codes are stored.
B. Record the stored trouble code
C. Check for additional stored trouble codes:
^ Remove the ALDL jumper wire and reinstall it.
^ Observe the "ANTILOCK" lamp again.
D. Record the stored trouble code.
E. Repeat steps C and D for additional codes.
4. Remove the ALDL jumper wire and turn the ignition switch to the 'OFF" position