P0657-SOLENOID SUPPLY VOLTAGE CIRCUIT
P0657-SOLENOID SUPPLY VOLTAGE CIRCUIT
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For a complete wiring diagram, refer to the Wiring Information.
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.
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When Monitored:
When the output is active and no undervoltage condition exists.
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Set Condition:
When the monitored supply voltage and battery voltage differ by 3.6 volts.
Possible Causes |
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| (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 (TCM) |
Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure).
1. (T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO VOLTAGE
| 1. | With the scan tool, check for other transmission DTCs. |
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 is a indication 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 in accordance with the Service Information.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure).
No
- Go To 2
2. (T78) SOLENOID SUPPLY VOLTAGE CIRCUIT OPEN
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| 1. | Turn the ignition off to the lock position. |
| 2. | Disconnect the TCM C1 and C2 harness connectors. |
| 3. | Disconnect the Electrohydraulic Control Unit Assembly harness connector. |
| 4. | Measure the resistance of the (T78) Solenoid Supply Voltage circuit between the TCM C2 harness connector and the Electrohydraulic Control Unit Assembly harness connector. |
Is the resistance above 5.0 Ohms?
Yes
- Repair the (T78) Solenoid Supply Voltage circuit for an open.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure).
No
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Go To 3
3. (T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO GROUND
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| 1. | Measure the resistance between ground and the (T78) Solenoid Supply Voltage circuit. |
Is the resistance below 5.0 Ohms?
Yes
- Repair the (T78) Solenoid Supply Voltage circuit for a short to ground.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure).
No
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Go To 4
4. (T78) SOLENOID SUPPLY VOLTAGE CIRCUIT SHORT TO ANOTHER CIRCUIT
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| 1. | Measure the resistance between the (T78) Solenoid Supply Voltage circuit and all other circuits in the 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 Electrohydraulic Control Unit Assembly harness connector?
Yes
- Repair the (T78) Solenoid Supply Voltage circuit for a short to another circuit(s).
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure)
No
- 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 in accordance with the Service Information.
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Perform the NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM)
- Standard Procedure).