P0657-SOLENOID SUPPLY VOLTAGE CIRCUIT

For a complete wiring diagram Refer to Section 8W

Theory of Operation

The Solenoid Supply Voltage output of the Transmission Control Module (TCM) provides the voltage to the three shift, two pressure and TCC solenoids. The output is active whenever the system is in normal operation. If a major system fault is detected, this output is turned off to ensure that no solenoids are active.

When Monitored:
When the output is active and no undervoltage condition exists.
Set Condition:
When the monitored supply voltage and battery voltage differ by 3.6 volts.

Possible Causes

(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT OPEN

(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO GROUND

(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO VOLTAGE

(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO ANOTHER CIRCUIT

TRANSMISSION CONTROL MODULE

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Diagnostic Test

1.(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO VOLTAGE

Is the DTC P1629-TCM INTERNAL - SOLENOID SUPPLY/WATCHDOG also present?

Yes

When both P0657-SOLENOID SUPPLY VOLTAGE CIRCUIT and P1629-TCM INTERNAL - SOLENOID SUPPLY/WATCHDOG DTCs set at the same time indicates that the (T78) Solenoid Supply Voltage circuit is shorted to voltage. Repair the Solenoid Supply Voltage circuit for a short to voltage. If no short to voltage is present, using the schematics as a guide, check the Transmission Control Module (TCM) terminals 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 for the appropriate service procedures.
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Go To 2

2.(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT OPEN

Is the resistance above 5.0 ohms?

Yes

Repair the (T78) Solenoid Supply Voltage circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Go To 3

3.(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO GROUND

Is the resistance below 5.0 ohms?

Yes

Repair the (T78) Solenoid Supply Voltage circuit for a short to ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Go To 4

4.(T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO ANOTHER CIRCUIT

Is the resistance below 5.0 ohms between the (T78) Solenoid Supply Voltage circuit and any other circuit(s) in the Electrohydraulic Control Unit Assembly harness connector?

Yes

Repair the (T78) Solenoid Supply Voltage circuit for a short to another circuit(s).
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Using the schematics as a guide, check the Transmission Control Module (TCM) terminals 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 for the appropriate service procedures.
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)