PCI Bus Communication Failure

NOTE: Determine which modules this vehicle is equipped with before proceeding.

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

Turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, attempt to communicate with the following modules (if equipped).
- Body Control Module (BCM)
- Mechanical Instrument Cluster (MIC) Module
- Occupant Restraint Controller (ORC)
- Controller Anti-Lock Brake (CAB)
If scan tool communicates with any of these modules, go to next step. If scan tool does not communicate with any of these modules, go to step 3 .
Turn ignition off. If scan tool is unable to communicate with specific modules, perform related NO RESPONSE symptom test. See SYMPTOM IDENTIFICATION table under SELF-DIAGNOSTIC SYSTEM. If scan tool communicates with all modules, fault may be intermittent. Check related wiring and connectors for poor connections or damage to wiring harness. See WIRING DIAGRAMS . Repair any problems found as necessary. If no problems are found, check if any Technical Service Bulletins (TSBs) apply to vehicle. If no TSBs apply, test is complete.
Turn ignition off. Disconnect BCM connector C1. Measure resistance of PCI bus circuit (Violet/Yellow wire) between DLC terminal No. 2 and BCM connector C1 terminal No. 14. 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/Yellow wire.
Ensure BCM connector C1 is reconnected. Turn ignition on. Measure voltage on DLC terminal No. 2, PCI bus circuit (Violet/Yellow wire). If voltage is more than 4 volts, go to next step. If voltage is 4 volts or less, go to step 7 .

Turn ignition off. Disconnect BCM connectors and remove BCM from back of junction block. Turn ignition on. Measure voltage on each PCI bus terminal (Violet/Yellow wire) at appropriate BCM connector. See PCI BUS COMPONENT/MODULE IDENTIFICATION table. See Figure and Figure . If voltage remains steadily more than 4 volts at any terminal, go to next step. If voltage does not remain steadily more than 4 volts at any terminal, replace BCM.

PCI BUS COMPONENT/MODULE IDENTIFICATION

BCM Connector Terminal No.

Component/Module

Back Of Junction Block ⁽¹⁾

Overhead Travel Information System Module

C1 ⁽²⁾

Automatic Temperature Control Module

Radio

Occupant Restraint Controller

Sentry Key Immobilizer Module

Mechanical Instrument Cluster

Data Link Connector

C3 ⁽²⁾

Powertrain Control Module

Controller Anti-Lock Brake

Transmission Control Module

C4 ⁽²⁾

Memory Heated Seat/Mirror Module & Side Impact Air Bag Control Modules

⁽¹⁾	See Figure .

⁽²⁾	See Figure .

Turn ignition off. Disconnect appropriate connectors at component(s) and/or module(s) for PCI bus circuit (Violet/Yellow wire) that voltage existed on in step 5 . Turn ignition on. Measure voltage on appropriate terminal(s) at appropriate BCM connector. See PCI BUS COMPONENT/MODULE IDENTIFICATION table. If voltage is steadily more than 4 volts with component/module connector(s) disconnected, repair short to voltage in appropriate wire. If voltage is not steadily more than 4 volts with component/module connector(s) disconnected, replace appropriate module(s).
Turn ignition off. Disconnect negative battery cable. Disconnect BCM connectors and remove BCM from back of junction block. Measure resistance between ground and each PCI bus terminal (Violet/Yellow wire) at appropriate BCM connector. See PCI BUS COMPONENT/MODULE IDENTIFICATION table. See Figure and Figure . If resistance is less than 5 ohms at any terminal, leave negative battery cable disconnected, and go to next step. If resistance is 5 ohms or more at all terminals, replace BCM.
Disconnect appropriate connectors at component(s) and/or module(s) for PCI bus circuit (Violet/Yellow wire) on which resistance is 5 ohms or less in step 7 . Measure resistance between ground and appropriate terminal(s) at appropriate BCM connector. See PCI BUS COMPONENT/MODULE IDENTIFICATION table. If resistance is less than 100 ohms with component/module connector(s) disconnected, repair short to ground in appropriate wire. If resistance is 100 ohms or more with component/module connector(s) disconnected, replace appropriate module(s).