PCI Bus Communication Failure

NOTE: After making any repairs, perform BODY VERIFICATION TEST under VERIFICATION TESTS.

NOTE: When attempting to communicate with any module, scan tool will display one of 2 different communication errors. A NO RESPONSE message or BUS +/- SIGNALS OPEN message.

Connect scan tool to Data Link Connector (DLC) located under left side of instrument panel. See Figure . Turn ignition on. Using scan tool, attempt to communicate with Body Control Module (BCM), Controller Anti-Lock Brakes (CAB), Electro/Mechanical Cluster (MIC) and Occupant Restrain Controller (ORC). If scan tool communicates with one or more modules, go to next step. If scan tool does not communicate with any modules, go to step 3 . If scan tool communicates with one or more modules, go to next step.
Turn ignition off. Visually inspect all related connectors and wiring harnesses and repair as necessary. See WIRING DIAGRAMS . Repair wiring as necessary. If scan If wiring is okay, diagnose communication problem for modules that did not communicate with scan tool. See SYMPTOM IDENTIFICATION table under SELF-DIAGNOSTIC SYSTEM.
Turn ignition off. Disconnect scan tool from Data Link Connector (DLC). Disconnect BCM C2 26-pin connector. BCM is connected to junction block under left side of instrument panel. Measure resistance of Violet/Gray wire between terminals No. 2 at DLC and No. 59 at PCM C2 harness connector. See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Violet/Gray wire.
Ensure ignition is off. Reconnect BCM C2 connector. Turn ignition on. Measure voltage between ground and terminal No. 2 (Violet/Gray wire) at DLC. If voltage is more than 4 volts, go to next step. If voltage is 4 volts or less, go to 7 .
Turn ignition off. Disconnect BCM C2 26-pin and C3 White 16-pin connectors. Turn ignition on. Measure voltage of PCI bus circuit for each control module that vehicle is equipped with at BCM C2 and C3 harness connectors. See WIRING DIAGRAMS . If voltage is not steady or less 4 volts or less on all PCI bus circuits, bus is okay. Replace BCM. If voltage is steady and more than 4 volts on any PCI circuit, go to next step.
Turn ignition off. Disconnect module that corresponds to PCI bus circuit than voltage was steady and more than 4 volts in step 5 . If PCI bus circuit for radio was more than 4 volts and vehicle is equipped with a CD changer, disconnect CD changer before disconnecting radio. If PCI bus circuit for instrument cluster was more than 4 volts and vehicle is equipped with a Compass/Mini-Trip Computer, disconnect CMTC before disconnecting instrument cluster. If PCI bus circuit for side air bags was more than 4 volts, disconnect each side impact air bag control module one at a time. Turn ignition on. Measure voltage of PCI bus circuit that previously measured more than 4 volts. If voltage is still more than 4 volts, repair short to voltage in PCI bus circuit. If voltage is now less than 4 volts, replace faulty module.
Turn ignition off. Disconnect negative battery cable. Disconnect BCM C2 26-pin and C3 White 16-pin connectors. Turn ignition on. Measure resistance between ground and PCI bus circuit for each control module that vehicle is equipped with at BCM C2 and C3 harness connectors. See WIRING DIAGRAMS . If resistance is more than 1000 ohms on all PCI circuits, replace BCM. If resistance is less than 1000 ohms on any PCI bus circuit, go to next step.
Disconnect control module that corresponds to PCI bus circuit that measured resistance is less than 1000 ohms. Measure resistance between ground and PCI circuit of suspect control module at BCM C2 or C3 harness connector. If resistance is 1000 ohms or more, replace faulty control module. If resistance is less than 1000 ohms, repair short to ground in PCI bus circuit.