Rear Wheel ABS

ISOLATION OF SUSPECT CIRCUIT
If a RWAL system complaint comes and goes intermittently, follow this procedure to isolate the suspect circuit:
1. If any diagnostic trouble code is stored in the EBCM, go to that diagnosis chart and follow it through step by step. Displaying & Reading Trouble Codes
2. Test drive the vehicle. If the owner's complaint is known, try to safely duplicate the conditions. Test Driving ABS Complaint Vehicles
3. Check again for any diagnostic trouble codes. If found, follow the diagnosis chart step by step.
4. If no diagnostic trouble code is stored, repeat Step 2 of preliminary checks under Flow of Diagnosis. Diagnostic Stratagies

CAN'T DUPLICATE PROBLEM
If you can't duplicate the problem, a detailed owner's complaint can help in pointing to the most likely component or circuit. Most intermittent problems are caused by faulty electrical connections (including grounds) or wiring. If you think an intermittent electrical problem exists, check the suspected circuit for:
^ Poor mating of connector terminals not fully seated in the connector body (backed out).
^ Improperly formed or damaged terminals. All connector terminals in a problem circuit should be reformed to increase contact tension.
^ Poor terminal to wire connection.
NOTE: You must remove the terminal from the connector body to check this. Be sure to reinstall the terminal properly.
^ Dirty or corroded terminals and/or connectors.

HARNESS AND CONNECTOR "SHAKE" TEST
If an intermittent problem condition can't be duplicated under normal conditions, perform the checks under DIAGNOSIS WITHOUT TROUBLE CODE (Charts A, B. C and D) while shaking the RWAL harness. This may help isolate an intermittent connection. Symptom Index

INTERMITTENT OPEN SENSOR SHOCK-TEST
If there are intermittent problems related to the speed sensor and the wiring harness checks OK, gently tap the sensor body while testing. There may be an intermittent bad connection within the sealed sensor unit.