No Response From Transfer Case Control Module
NOTE:
After making any repairs, perform TRANSFER CASE VERIFICATION TEST
under VERIFICATION TESTS.
- Connect scan tool to Data Link Connector (DLC), under lower left side of instrument panel. Turn ignition on. Select BODY, then BODY COMPUTER. If scan tool is able to identify or communicate with Central Timer Module (CTM) and/or Air Bag Control Module (ACM), go to next step. If scan tool is not able to identify or communicate with CTM and/or ACM, see PCI BUS COMMUNICATION FAILURE .
- Turn ignition off. Disconnect Transfer Case Control Module (TCCM) electrical connectors. TCCM is located behind instrument panel, to right of steering column. Using test light connected to ground, probe Black 4-pin TCCM connector C3 terminal "B" (Light Blue/Red wire). See Fig 1 . If test light illuminates brightly, go to next step. If test light illuminates dimly or does not illuminate, check fuse "A" (20-amp) located in power distribution center. Power distribution center is located in left side of engine compartment, near battery. See Figure . If fuse is okay, repair open in Light Blue/Red wire between Black 4-pin TCCM connector C3 terminal "B" and fuse "A" in power distribution center. See POWER DISTRIBUTION article in WIRING DIAGRAMS. If fuse is blown, check for short to ground in Light Blue/Red wire between Black 4-pin TCCM connector C3 terminal "B" and fuse "A" in power distribution center. Repair as necessary.
- Using test light connected to battery voltage, probe Black 16-pin TCCM connector C1 terminal A8 and Black 4-pin connector C3 terminal "A" (Black wires). See Fig 2 . If test light illuminates brightly on both circuits, go to next step. If test light illuminates dimly or does not illuminate on either circuit, repair open in appropriate Black wire between TCCM and ground. See GROUND DISTRIBUTION article in WIRING DIAGRAMS.
- Ensure there is PCI BUS communication with other modules before proceeding. If there is no PCI BUS communication with other modules, perform appropriate test relating to no communication. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table under SELF-DIAGNOSTIC SYSTEM. Connect Scope Input Cable (CH7058) to channel one connector on scan tool. Connect Cable-To-Probe Adapter (CH7062) and Black and Red test probes to scope input cable. Connect Black test probe to ground. Connect Red test probe to PCI BUS circuit at Black 16-pin TCCM connector C1 terminal A1 (Violet/Yellow wire).
- Using scan tool, select PEP MODULE TOOLS, LAB SCOPE, LIVE DATA. Select 12 VOLT SQUARE WAVE. Press F2 for SCOPE. Press F2 and use DOWN arrow to set voltage scale to 20 volts. Press F2 again when complete. Turn ignition on. If reading on lab scope toggles between zero and 7.5 volts, replace TCCM. Information on TCCM replacement is not available from manufacturer. If reading on lab scope does not toggle between zero and 7.5 volts, repair open in PCI BUS circuit (Violet/Yellow wire).