P0770-4C SOLENOID CIRCUIT
For a complete wiring diagram Refer to Section 8W
When Monitored:
Initially at power-up, then every 10 seconds thereafter. The solenoid circuits will also be tested immediately after a gear ratio or pressure switch error is detected.
Set Condition:
After three consecutive solenoid continuity test failures, or one failure if test is run in response to a gear ratio or pressure switch error. Note: This DTC is strictly an electrical fault and does not apply to any internal transmission failures.
Possible Causes
RELATED RELAY DTC'S PRESENT
(T259) 4C SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS
(T259) 4C SOLENOID CONTROL CIRCUIT OPEN
(T259) 4C SOLENOID CONTROL CIRCUIT SHORT TO GROUND
TRANSMISSION SOLENOID/TRS ASSEMBLY
POWERTRAIN CONTROL MODULE
Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
Theory of Operation
The Transmission Control System uses six electronically controlled solenoids that allow hydraulic fluid to be applied to various friction elements (clutches), which enables the gear requested. The continuity of each solenoid circuit is periodically tested. Each inactive solenoid is turned on for a few milliseconds, then off. Each active solenoid is turned off for a few milliseconds, then on. This pulsing of voltage to the solenoid causes an inductive spike which can be sensed by the Transmission Control System. If an inductive spike is not sensed by the Transmission Control System during the continuity check, it is tested again. If the test fails three consecutive times, the appropriate Diagnostic Trouble Code (DTC) is set. If the solenoid test is run in response to a gear ratio or pressure switch error, one failure will result in setting the appropriate DTC. Note: This DTC is strictly an electrical fault and does not apply to any internal transmission failures.
Diagnostic Test
1. RELATED TRANSMISSION RELAY DTC'S PRESENT
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With the scan tool, check for other transmission DTC's.
Are there any Transmission Control Relay DTC's present?
Yes
Refer to the Transmission category and perform the appropriate symptom. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - DIAGNOSIS AND TESTING)
No
Go To 2
2. CHECK TO SEE IF P0770 IS PRESENT
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Turn the ignition off to the lock position.
Remove the Starter Relay.
NOTE: Removal of the Starter Relay is to prevent a Transmission, NO RESPONSE, condition and disable the starter.
Install Transmission Simulator, Miller tool #8333.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
With the scan tool, actuate the 4C Solenoid.
Monitor the 4C Solenoid LED on the Transmission Simulator.
Did the 4C Solenoid LED on the Transmission Simulator blink on and off?
Yes
Go To 3
No
Go To 4
3. CHECK THE TRANSMISSION SOLENOID/TRS ASSEMBLY
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With the scan tool, continue to actuate the 4C Solenoid for the period of 2 minutes with the Transmission Simulator still connected.
After 2 minutes of actuation, with the scan tool, stop the actuation and check for transmission DTCs.
Did the DTC P0770 reset during the actuation test?
Yes
Go To 4
No
Replace the Transmission Solenoid/TRS Assembly per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE/TRANS SOLENOID/TRS ASSY - REMOVAL)
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
4. CHECK THE (T259) 4C SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
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Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool #8333.
Disconnect the PCM harness connectors.
Measure the resistance between the (T259) 4C Solenoid Control circuit and all other circuits in the Transmission Solenoid/TRS Assembly harness connector.
Is the resistance below 5.0 ohms between the (T259) 4C Solenoid Control circuit and any other circuit(s) in the Transmission Solenoid/TRS Assembly harness connector?
Yes
Repair the (T259) 4C Solenoid Control circuit for a short to another circuit(s).
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
Go To 5
5. CHECK THE (T259) 4C SOLENOID CONTROL CIRCUIT FOR AN OPEN
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Connect Miller tool #8815 to the PCM C4 harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller special tool #8815 to perform diagnosis.
Measure the resistance of the (T259) 4C Solenoid Control circuit from the Transmission Solenoid/TRS Assembly harness connector to the appropriate terminal of Miller tool #8815.
Is the resistance above 5.0 ohms?
Yes
Repair the (T259) 4C Solenoid Control circuit for an open.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
Go To 6
6. CHECK THE (T259) 4C SOLENOID CONTROL CIRCUIT FOR A SHORT TO GROUND
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Measure the resistance between ground and the (T259) 4C Solenoid Control circuit.
Is the resistance below 5.0 ohms?
Yes
Repair the (T259) 4C Solenoid Control circuit for a short to ground.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the PCM per the Service Information. With the scan tool, perform QUICK LEARN.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)