The ABS electronic control module (which may be referred to as an EBCM "Electronic Brake Control Module") is a microprocessor that functions like the engine control computer. To troubleshoot the ABS system you may need to check the codes stored in the EBCM. You must short two pins on the ALDL connector located under the dash on the drivers side.
Checking ABS codes cannot be done with code scanner or through the Reatta diagnostics screen.
About ABS Codes
ABS codes are stored in non-volatile memory.You cannot clear the codes by unplugging the ECBM, disconnecting the battery cables or turning off the ignition switch.
To clear the ABS codes you must drive the car over 18 miles per hour and they will automatically be cleared if you have repaired all problems that caused the ABS trouble codes to set. If you drive the car greater than 18 miles per hour and the yellow ABS light comes on the ECBM is still detecting a problem and codes will be present when you check the codes again.
The ECBM will not allow the codes to be cleared unless ALL codes have been read.
How to enable ABS diagnostics:
With the key off remove the ALDL cover to expose the terminals as shown below.
The photo above shows terminals "A" and "H" jumped on the ALDL of a 1989 model Reatta.
1988 models use different terminals (A&G) but the procedure for jumping the ALDL is the same.
How to check 1988-1990 ABS codes
Using a piece of wire or a small paper clip, jumper the following terminals in the ALDL connector:
- 1988 model - terminals A&G
- 1989 and 1990 model - terminals A&H
- Turn the key ON.
- Yellow ABS light will flash.
- Count the flashes.
- The light will flash a number of times, pause, then flash some more.
- Write down the codes.
- While leaving the key ON, remove the jumper, then put it back.
- If there is a second code it will flash.
- Repeat removing and replacing the jumper until the yellow light stays on steady.
- This will give you all the codes stored in the EBCM.
EXAMPLE:
First code with key on:
Flash + Flash
Pause
Flash + Flash
Pause
Then ABS light stays on solid
This would be a code 22 (Flash, Flash + Flash, Flash =22)
Then while the key is still ON take off the jumper and re-insert:
Flash
Pause
Flash + Flash + Flash
Pause
Then ABS light stays on solid.
This would be a code 13 (Flash + Flash, Flash, Flash =13)
How to check 1991 ABS codes
- Turn ignition ON.
- If anti-lock light does not turn off within 4 seconds note this and go to step 2. - Turn ignition OFF.
- Must be off to enter ABS diagnostics. - Ground ALDL pin H.
- Using a piece of wire or a small paper clip, jumper between pin H and ALDL pin A (ground).
- Turn ignition switch to RUN (engine OFF)
- Count flashes of anti-lock light for initialization sequence:
ANTI-LOCK light will turn on for approximately 4 seconds then turn off. Display of blink codes will then begin. Each digit will be blinked out by a .5 second flash of the ANTI-LOCK light. There is a 1.25 second pause (light off) between each digit.
Code "12" will blink out 3 times in succession. This is not a fault code, but indicates ABS diagnostics has been entered.
After code "12" has blinked out three times, any stored fault codes are then blinked out, each with a 3 second pause between. After any and all codes have displayed, the sequence repeats.
EXAMPLE:
First code with key on:
Flash + Flash
Pause
Flash + Flash
Pause
Then ABS light stays on solid
This would be a code 22 (Flash, Flash + Flash, Flash =22)
ABS Codes as follows:
WSS=wheel speed sensor fault
TWF=toothed wheel frequency fault
SVF=solenoid valve fault
EBCM=electronic brake control module
21 - R front WSS
22 - R front TWF
25 - L front WSS
26 - L front TWF
31 - R rear WSS
32 - R rear TWF
35 - L rear WSS
36 - L rear TWF
41 - R front SVF
45 - L front SVF
55 - Rear axle SVF
61 - Motor pump circuit fault
63 - Solenoid valve relay fault
71 - EBCM fault
72 - Serial data link fault (TECH 1 error)
Click here for a chart of ABS codes.
Refer to the Field Service Manual (FSM) for interpreting the codes and troubleshooting the ABS system.
Thanks to Padgett, and other members of the Reatta forums, for this information.
