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

NOTE: After making any repairs, perform 41TE TRANSMISSION VERIFICATION TEST under VERIFICATION TESTS.

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 Powertrain Control Module (PCM) and Body Control Module (BCM). If scan tool communicates with both modules, go to next step. If scan tool does not communicate with PCM, go to NO RESPONSE FROM PCM (PCI BUS) . If scan tool does not communicate with BCM, go to BUS +/- SIGNALS OPEN OR NO RESPONSE FROM BODY CONTROL MODULE .
Disconnect Transmission Control Module (TCM). TCM is located next to power distribution center in left front corner of engine compartment. See Figure . Turn ignition on. Using a test light connected to ground, probe terminal No. 11 (Red/White wire) at TCM harness connector. See Figure . If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open or high resistance in Red/White wire between TCM and fuse No. 11 (10-amp) in junction block. Junction block is located under left side of instrument panel. Also check fuse No. 11 in junction block.

NOTE: Starter relay may also be referred to as engine starter motor relay.

Turn ignition off. Remove starter relay from Power Distribution Center (PDC). See Figure . PDC is located on left side of engine compartment, near battery. Using a test light connected ground, probe terminal No. 9 at starter relay socket in PDC. See Figure . Observe test light while momentarily turning ignition switch to START position. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open in Yellow wire between PDC and ignition switch.
Using a test light connected to ground, probe terminal No. 56 (Black wire) at TCM harness connector. See Figure . If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open or high resistance in Black wire between TCM and fuse No. 9 (20-amp) in junction block. Also check fuse No. 9 in junction block.
Using a test light connected to positive battery voltage, probe terminals No. 53 (Black/Yellow wire) and No. 57 Black/Red wire) at TCM harness connector. If test light illuminates at both terminals, go to next step. If test light does not illuminate at one or both terminals, repair open or high resistance in Black/Yellow wire and/or Black/Red wire between TCM and ground.
Using Scope Input Cable (CH7058), Cable-To-Probe Adapter (CH7062), and Red and Black test leads, connect scope input cable to channel one connector. Attach Red and Black leads and cable-to-probe adapter to scope input cable. Using DRBIII(R), select PEP MODULE TOOLS, LAB SCOPE, LIVE DATA, then 12-VOLT SQUARE WAVE. Press F2 for SCOPE and ENTER to select channel. Press F2 to set voltage range to 20-volts. Press F2 again when complete. Connect Black lead to ground. Connect Red lead to terminal No. 43 (Violet/Yellow wire) at TCM harness connector. See Figure . Turn ignition on. Observe voltage display on lab scope. Voltage should pulse between zero and 7.5-volts. If voltage is as specified, replace TCM. See TRANSMISSION CONTROL MODULE under REMOVAL & INSTALLATION. If voltage is not as specified, go to next step.
Turn ignition off. Ensure TCM is disconnected. Disconnect BCM C3 White 16-pin connector. BCM is connected to junction block under left side of instrument panel. Measure resistance of Violet/Yellow wire between terminals No. 3 at BCM C3 harness connector and No. 43 at TCM harness connector. See Figure and Figure . If resistance is more than 5 ohms, repair open in Violet/Yellow wire. If resistance is less than 5 ohms, replace BCM.