Test C: Scan Tool Does Not Communicate With Keyword Data Line

Ensure battery condition, cold cranking amperage and reserve capacity meet specifications. Replace as necessary. Install scan tool to Data Link Connector (DLC). If scan tool powers up, go to next step. If scan tool does not power up, go to TEST B: SCAN TOOL DOES NOT POWER UP .
Turn ignition on, with engine off. Try to establish scan tool communication with each module on data line:
- Theft Deterrent Module and Sun Roof Actuator at DLC terminal No. 3.
- Transmission Control Module (TCM), Driver Memory Seat Module (DMSM), Instrument Panel Cluster (IPC) and Engine Control Module (ECM) at DLC terminal No. 7.
- Automatic level control sensor at DLC terminal No. 8.
- Inflatable Restraint Sensing and Diagnostic Module (SDM), Power Steering Control Module, Heater-A/C Control and Electronic Brake/Traction Control Module (EBCM) at DLC terminal No. 12.
If communication with modules on designated DLC terminal is not established, go to next step. If communication with any module on designated DLC terminal is established, check for intermittent and poor connections between DLC and suspect module.
Turn ignition off. Disconnect scan tool from DLC. Disconnect any non-communicating modules on keyword serial data circuit that exhibited a communications concern. Check for an open in keyword serial data communications circuits (Brown/White wire) between DLC and any device. If an open was located and repaired, go to step 7 . If an open was not located and repaired, go to next step.
Check following circuits to module that is not communicating:
- Battery positive voltage circuit for an open or short to ground.
- Ignition positive voltage circuit for an open or short to ground.
- Ground circuit for an open.
- ECM power relay operation. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
If a malfunction was located and repaired, go to step 7 . If a malfunction was not located and repaired, go to next step.
Inspect harness connectors for poor connections and bad terminal contact of non-communicating module containing battery positive, ignition positive, ground and keyword serial data communications circuits. If malfunction is located and repaired, go to step 7 . If malfunction was not located and repaired, go to next step.

NOTE: Perform set up procedure for module being replaced, if required.

Replace module that is not communicating on keyword serial data communications circuit. See REMOVAL & INSTALLATION . After replacement, go to next step.
Reconnect any connectors and modules that were disconnected. Install scan tool. Turn ignition on, with engine off. Attempt to communicate with module that was not communicating. If scan tool communicates with module, system is okay. If scan tool does not communicate with module, go to step 2 .