Bus +/- Signals Open Or No Response From Body Control Module

Possible Causes:

Attempt To Communicate With Another Module
Open Ground Circuit
Open PCI Bus Circuit
Body Control Module

Testing

Turn the ignition on. With the DRBIII(R), attempt to communicate with the Airbag Control Module (ACM). With the DRBIII(R), attempt to communicate with the Controller Anti-lock Brake (CAB) module. Was the DRBIII(R) able to I/D or communicate with the ACM or the CAB? If yes, go to next step. If no, see SYMPTOM IDENTIFICATION table for PCI Bus Communication Failure. Perform BODY VERIFICATION TEST .
Turn the ignition off. Disconnect the BCM C1 harness connector. Using a 12-volt test light connected to 12-volts, probe each ground circuit. Is the test light illuminated for each circuit? If yes, go to next step. If no, repair the ground circuit for an open. Perform BODY VERIFICATION TEST .

NOTE: Ensure there is PCI Bus communication with other modules on the vehicle before proceeding. If not, diagnose and repair Communication problem as necessary. See COMMUNICATIONS in DIAGNOSTIC TROUBLE CODE IDENTIFICATION and SYMPTOM IDENTIFICATION tables.

Disconnect the Bcm C1 harness connector. Use Scope Input Cable (CH7058), Cable-to-Probe Adapter (CH7062), and the red and black test probes. Connect the scope input cable to the channel one connector on the DRBIII(R). Attach the red and black leads and the cable to probe adapter to scope input cable. With the DRBIII(R) select Pep Module Tools. Select the scope. Select Live Data. Select 12-volt square wave. Press F2 for scope. Press F2 and use the down arrow to set voltage range to 20-volts. Set Probe to x10. Press F2 again when complete. Connect the Black lead to the chassis ground. Connect the Red lead to the PCI Bus circuit in the BCM connector. Turn the ignition on. Observe the voltage display on the DRBIII(R) Lab Scope. Does the voltage pulse from 0 to approximately 7.5 volts? If yes, test is complete. If no, repair the PCI Bus circuit for on open. Perform BODY VERIFICATION TEST .