No Response From Transmission Control Module

Possible Causes:

• No Response From Transmission Control Module
• Fused Ignition Switch Output (Run/Start) Circuit Open
• Fused Ignition Switch Output (Start) Circuit Open
• Fused B+ Circuit Open
• Ground Circuit(s) Open
• Open PCI Bus Circuit
• Transmission Control Module

Testing

NOTE: As soon as one or more module communicates with the DRBIII(R), answer the question.
1. Turn the ignition on. With the DRBIII(R), attempt to communicate with the Airbag Control Module (ACM) and the Body Control Module (BCM). Was the DRBIII(R) able to I/D or establish communications with either of the modules? If yes, go to next step. If no, refer to PCI BUS COMMUNICATION FAILURE  . Perform TRANSMISSION VERIFICATION TEST  .
NOTE: In the following steps, the light must illuminate brightly. If it does not light, or lights dimly, the circuit must be repaired. If there is any doubt, compare the brightness when testing the circuit to the brightness when connected directly to the battery positive post.
2. Turn the ignition off. Disconnect the TCM harness connector. Turn the ignition on. Using a 12-volt test light connected to ground, probe the Fused Ignition Switch Output. (Run/Start) circuit. Is the test light illuminated? If yes, go to next step. If no, repair the Fused Ignition Switch Output (Run/Start) circuit for an open. See WIRING DIAGRAMS  . Perform TRANSMISSION VERIFICATION TEST  .
NOTE: Reinstall the original Starter Relay.
3. Turn the ignition off. Disconnect the TCM harness connector. Remove the starter relay from the PDC. Using a 12-volt test light connected to ground, probe the Fused Ignition Switch Output (Start) circuit. Observe the test light while momentarily turning the ignition switch to the Start position. Is the test light illuminated? If yes, go to next step. If no, repair the Fused Ignition Switch Output (Start) circuit for an open. See WIRING DIAGRAMS  . Perform TRANSMISSION VERIFICATION TEST  .
4. Turn the ignition off. Disconnect the TCM harness connector. Using a 12-volt test light connected to ground, probe the Fused B+ circuit. Is the test light illuminated? If yes, go to next step. If no, repair the Fused B+ circuit for an open. See WIRING DIAGRAMS  . Perform TRANSMISSION VERIFICATION TEST  .
5. Turn the ignition off Disconnect the TCM harness connector. Using a 12-volt test light connected to 12-volts, probe each ground circuit in the TCM connector. Is the light illuminated at all ground circuits? If yes, go to next step. If no, repair the Ground circuit(s) for an open. Check the main ground connection to engine block and/or chassis. See WIRING DIAGRAMS  . Perform TRANSMISSION VERIFICATION TEST  .
NOTE: Ensure there is PCI Bus Communication with other modules on the vehicle before proceeding. If not, diagnose and repair Communication problem as necessary. See COMMUNICATIONS in DIAGNOSTIC TROUBLE CODE IDENTIFICATION  and SYMPTOM IDENTIFICATION  tables.
6. Disconnect the TCM harness connector. Use Scope Input Cable (CH7058), Cable-to-Probe Adapter (CH7062), and the red and black test probes. Connect the scope input cable to the channel one connector on the DRBIII(R). Attach the red and black leads and the cable to probe adapter to the scope input cable. With the DRBIII(R) select lab scope, select Live Data, select 12-volt square wave. Press F2 for Scope. Press F2 and use the down arrow to set voltage range to 20-volts. Set Probe to x10. Press F2 again when complete. Connect the Black lead to the chassis ground. Connect the Red lead to the PCI Bus circuit is the TCM connector. Turn the ignition on. Observe the voltage display on the DRBIII(R) Lab Scope. Does the voltage pulse from 0 to approximately 7.5 volts? If yes, go to next step. If no, repair the PCI Bus circuit for an open. Perform TRANSMISSION VERIFICATION TEST  .
7. If there are no possible causes remaining, replace the Transmission Control Module. See TRANSMISSION CONTROL MODULE (TCM)  . Perform TRANSMISSION VERIFICATION TEST  .