No Response From Controller Antilock Brake
NO RESPONSE FROM CONTROLLER ANTILOCK BRAKENo Response From Controller Antilock Brake:
POSSIBLE CAUSES
- Fused B+ circuit(s) open
- Traction system relay output circuit open
- Ground circuit(s) open
- SCI transmit circuit open
- SCI transmit circuit shorted to ground
- SCI transmit circuit shorted to voltage
- Shift lever assembly
- Controller antilock brake module
DIAGNOSTIC TEST
1. CHECK COMMUNICATION WITH OTHER MODULES
Turn the ignition on.
Using the DRB III(R), attempt to communicate with the PCM.
Q: Is the DRB III(R) able to communicate with the PCM?
YES: Go to 2
NO: Perform Symptom *No Response From All Modules. No Response From All Modules
2. CHECK COMMUNICATION WITH OTHER MODULES ON SCI TRANSMIT CIRCUIT
With the ignition on.
Using the DRB III(R), attempt to communicate with the Shift Lever Assembly.
Q: Is the DRB III(R) able to communicate with the Shift Lever Assembly?
YES: Go to 3
NO: Go to 7
3. FUSED B+ CIRCUIT(S) OPEN
Turn the ignition off.
Disconnect the CAB harness connector.
NOTE: Check connector - Clean/repair as necessary.
Turn the ignition on.
Measure the voltage of the Fused B+ circuits at the CAB harness connector.
Q: Is the voltage above 10 volts?
YES: Go to 4
NO: Repair the Fused B+ circuit(s) for an open. Perform ABS VERIFICATION TEST. ABS Verification Test
4. TRACTION SYSTEM RELAY OUTPUT CIRCUIT OPEN
With the ignition on.
Measure the voltage of the Traction System Relay Output circuit at the CAB harness connector.
Q: Is the voltage above 10 volts?
YES: Go to 5
NO: Repair the Traction System Relay Output circuit for an open. Perform ABS VERIFICATION TEST. ABS Verification Test
5. GROUND CIRCUIT(S) OPEN
Turn the ignition off.
Measure the resistance of the Ground circuits from the CAB harness connector to ground.
Q: Is the resistance below 5.0 ohms?
YES: Go to 6
NO: Repair the Ground circuit(s) for an open. Perform ABS VERIFICATION TEST. ABS Verification Test
6. SCI TRANSMIT CIRCUIT OPEN
With the ignition off.
Measure the resistance of the SCI Transmit circuit from the CAB harness connector to the DLC.
Q: Is the resistance below 5.0 ohms?
YES: Replace the Controller Antilock Brake. Perform ABS VERIFICATION TEST. ABS Verification Test
NO: Repair the SCI Transmit circuit for an open. Perform ABS VERIFICATION TEST. ABS Verification Test
7. DISCONNECT MODULES
NOTE:
- The Controller Antilock Brake and Shift Lever Assembly both use the SCI Transmit circuit at DLC cavity 9 to communicate with the DRB III(R). If one of these modules keeps the SCI Transmit circuit artificially high or low, the DRB III(R) will not be able to communicate with either of the modules.
- Perform the following steps for each of the modules until communication is restored with the other module or until each of the modules has been eliminated as the cause of the fault.
Turn the ignition off.
Disconnect each of the modules noted above, one at a time.
Turn the ignition on.
Using the DRB III(R), attempt to communicate with the other module still connected.
Q: Is the DRB III(R) able to communicate with the other module?
YES: Replace the module that was disconnected when communication was restored to the other module. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Go to 8
8. SCI TRANSMIT CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the harness connectors for the Controller Antilock Brake and Shift Lever Assembly.
Turn the ignition on.
Measure the voltage of the SCI Transmit circuit at DLC cavity 9.
Q: Is the voltage below 0.5 volt?
YES: Go to 9
NO: Repair the SCI Transmit circuit for a short to voltage. Perform BODY VERIFICATION TEST. Body Verification Test
9. SCI TRANSMIT CIRCUIT SHORTED TO GROUND OR OPEN
Turn the ignition off.
Measure the resistance between ground and the SCI Transmit circuit.
Q: Is the resistance above 100 kohms?
YES: Repair the SCI Transmit circuit for an open. Perform BODY VERIFICATION TEST. Body Verification Test
NO: Repair the SCI Transmit circuit for a short to ground. Perform BODY VERIFICATION TEST. Body Verification Test