Questions and Answers

Cadillac Seville ABS Not Working Q. Dear Mr. Ciulla, Thank you for sharing your knowledge. We need some advice. After 140,000 good miles our 1989 Cadillac Seville brakes have needed a lot of repair. We had to have the booster replaced at $800.00 and just had to have a wheel sensor replaced at $250.00.

After the repair we were then told that the mechanics could not reset the control unit and that it, too, would have to be replaced, but that part was no longer available. So we now have a new wheel sensor but no ABS.

Your suggestions would be welcome.
John

A. Basically we have to clear the DTC's from the Electronic Brake Control Module (EBCM) for the ABS system to become functional again. There is a special procedure to clear the codes that I suspect your mechanic is not aware of. It is a very simple procedure that you can easily do yourself.

The ABS trouble codes should not be cleared until repairs are completed. The EBCM will not allow the ABS codes to clear unless all codes have been read.

To read the ABS codes:

Fig. 7 1989 ABS Diagnostic Enable, ALDL Pin H (Part 1 Of 2)

Fig. 7 1990 ABS Diagnostic Enable, ALDL Pin H (Part 2 Of 2)

1. With ignition switch turned to the On position, allow pump/motor to charge the accumulator. If accumulator is discharged, the "BRAKE'' and "ANTI-LOCK'' lamps will remain on for up to 30 seconds.
2. If the "ANTI-LOCK'' lamp does not go off within 30 seconds, note that lamp did not go off, then proceed to step 3.
3. With ignition switch turned to the Off position, place a jumper wire between Assembly Line Diagnostic Link (ALDL), pin H and body ground on 1989-90 models Fig. 7. The ALDL is located on the driver's side of the vehicle near the parking brake pedal assembly.
4. Turn ignition switch to the RUN position, then count the lamp flashes to identify the first digit. If the lamp turns on for four seconds, then turns off (and remains off), no trouble codes are present. Proceed to ABS FUNCTIONAL CHECK, then proceed with diagnosis as directed. If the EBCM has stored any trouble codes, the "ANTI-LOCK'' lamp will turn on for approximately four seconds and will then start flashing. These flashes represent the first digit of the trouble code.

Fig. 8 ABS Diagnostic Code Interpretation

5. Count lamp flashes for the second digit. The lamp will pause (remain off), for approximately three seconds after flashing the first digit. It will then flash the second digit of the trouble code. When the "ANTI-LOCK'' lamp flashes the second digit of the trouble code, be careful to count only the number of times the lamp turns on and goes out. When the EBCM is done flashing the second digit, the "ANTI-LOCK'' lamp will remain on. The last pulse, when the lamp remains on, should not be counted as a flash, Fig. 8.
6. Record trouble codes obtained.
7. Check for additional trouble codes. Without turning the ignition switch to the off position, disconnect the jumper wire from ALDL pin H on 1989-90 models. Connect the jumper again to ALDL pin. If an additional code is present, the "ANTI-LOCK'' lamp will begin flashing the first digit as described previously. Count lamp flashes for the first and second digits as was done for the first code. Record the additional trouble code if present.
8. Repeat steps 6 and 7, until no additional trouble codes are displayed. Up to seven trouble codes can be displayed. The "ANTI-LOCK'' lamp will remain on continuously when all trouble codes have been displayed. ABS trouble codes cannot be cleared unless all codes have been displayed.
9. After recording all ABS codes, remove jumper from the ALDL, install ALDL cover, then proceed with the ABS FUNCTIONAL CHECK.

The ABS trouble codes are cleared by driving the vehicle at a speed greater than 18 mph. If the codes did not clear, repeat the read out procedure and drive the vehicle again at a speed greater than 18 mph. If codes do not clear, additional repairs may be required.

Disconnecting the EBCM, battery cables, or turning the ignition switch to the Off position, will not clear the trouble codes from memory.

And if you do need the EBCM, the part number is 1640037 and the price is $982.98. You can get it at any Cadillac Dealer.