P1629-TCM INTERNAL - SOLENOID SUPPLY/ WATCHDOG
For a complete wiring diagram Refer to Section 8W
Theory of Operation
The Transmission Control Module (TCM) performs various internal tests to verify proper controller operation. During the power up of the controller, the TCM tests the ability of the TCM to shut down the Solenoid Supply Voltage circuit. The controller monitors the A/D feedback on the Solenoid Supply driver output to ensure that battery voltage is no longer present. Note: A short to voltage on the Solenoid Supply Voltage circuit or any one of the solenoids may set this DTC.
- When Monitored:
Continuously with the ignition on.
- Set Condition:
If the TCM detects voltage on the Solenoid Supply Voltage circuit when the TCM request the circuit to be off.
| Possible Causes |
| (T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO VOLTAGE |
| TRANSMISSION CONTROL MODULE |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)
Diagnostic Test
1. CHECK THE (T78) SOLENOID SUPPLY VOLTAGE CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Turn the ignition off to the lock position.
Disconnect the TCM C1 and C2 harness connectors.
Disconnect the Transmission Electrohydraulic Control Unit Assembly harness connector.
Measure the resistance between the (T78) Solenoid Supply Voltage circuit and every other circuit in the Transmission Electrohydraulic Control Unit Assembly harness connector.
Is the resistance below 5.0 ohms between the (T78) Solenoid Supply Voltage circuit and any other circuit(s) in the Transmission Electrohydraulic Control Unit Assembly harness connector?
Yes
- Repair the (T78) Solenoid Supply Voltage circuit for short to another circuit.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)
No
- Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM per the Service Information. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - REMOVAL)
- Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)