No Response From BCM (Body Control Module)

*NO RESPONSE FROM BODY CONTROL MODULE









Diagnostic Test

1. CHECK COMMUNICATION WITH OTHER MODULES





Turn the ignition on.

Using the DRB III(R), attempt to communicate with the PCM.

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 Sentry Key Remote Entry Module.

Is the DRB III(R) able to communicate with the Sentry Key Remote Entry Module?

Yes

- Go to 3

No

- Go to 7

3. FUSED B+ CIRCUIT(S) OPEN

Turn the ignition off.

Disconnect the BCM harness connectors.

NOTE: Check connector - Clean/repair as necessary.

Turn the ignition on.

Measure the voltage of the Fused B+ circuits at the BCM C4 harness connector.

Is the voltage above 10 volts?

Yes

- Go to 4

No

- Repair the Fused B+ circuit(s) for an open.
- Perform BODY VERIFICATION TEST. Body Verification Test

4. FUSED IGNITION SWITCH OUTPUT CIRCUIT(S) OPEN





With the ignition on.

Measure the voltage of the Fused Ignition Switch Output circuits at the BCM C4 harness connector.

Is the voltage above 10 volts?

Yes

- Go to 5

No

- Repair the Fused Ignition Switch Output circuit(s) for an open.
- Perform BODY VERIFICATION TEST. Body Verification Test

5. GROUND CIRCUIT(S) OPEN





Turn the ignition off.

Measure the resistance of the Ground circuits from the BCM C4 harness connector to ground.

Is the resistance below 5.0 ohms?

Yes

- Go to 6

No

- Repair the Ground circuit(s) for an open.
- Perform BODY VERIFICATION TEST. Body Verification Test

6. SCI TRANSMIT CIRCUIT OPEN





With the ignition off.

Measure the resistance of the SCI Transmit circuit from the BCM C4 harness connector to the DLC.

Is the resistance below 5.0 ohms?

Yes

- Replace the Body Control Module.
- Perform BODY VERIFICATION TEST. Body Verification Test

No

- Repair the SCI Transmit circuit for an open.
- Perform BODY VERIFICATION TEST. Body Verification Test

7. DISCONNECT MODULES





NOTE: The Body Control Module and Sentry Key Remote Entry Module both use the SCI Transmit circuit at DLC cavity 1 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.

NOTE: 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.

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 Body Control Module and Sentry Key Remote Entry Module.

Turn the ignition on.

Measure the voltage of the SCI Transmit circuit at DLC cavity 1.

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.

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