For a complete wiring diagram Refer to Section 8WThe 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. 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. This DTC is strictly an electrical fault and cannot be caused by any internal transmission failure other than an open in the Transmission Solenoid/TRS Assembly. If the Transmission Solenoid/TRS Assembly is in need of replacement — do not replace the Valve Body.Possible CausesRELATED DTCS PRESENT(T259) 4C SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS(T259) 4C SOLENOID CONTROL CIRCUIT OPEN(T259) 4C SOLENOID CONTROL CIRCUIT SHORT TO GROUNDTRANSMISSION SOLENOID/TRS ASSEMBLYPOWERTRAIN CONTROL MODULEAlways perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) 1. CHECK DTCSWith the scan tool, check DTCs.Are there any TIPM TCM Power Control Circuit or TCM Power Input DTCs present?YesRefer to the Transmission category and perform the appropriate symptom.NoGo To 22. CHECK TO SEE IF P0770 IS PRESENTTurn the ignition off to the lock position.Remove the Ignition Switch Feed fuse from the TIPM.Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear. The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in personal injury or death.Install Transmission Simulator, Miller tool #8333.Ignition on, engine not running.With the scan tool, clear Transmission DTCs.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?YesGo To 3NoGo To 53. CHECK THE TRANSMISSION SOLENOID/TRS ASSEMBLYWith the Transmission simulator still connected, continue to actuate the 4C solenoid for 2 minutes.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?YesGo To 5NoGo To 44. WIGGLE TEST WITH TRANSMISSION SIMULATORWith the Transmission simulator still connected, continue to actuate the 4C solenoid for another 2 minutes while wiggling the related wiring harness and connectors.With the scan tool, stop the actuation and check for transmission DTCs.Did the DTC P0770 reset during the actuation test?YesRepair wiring harness or connectors as necessary.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoReplace the Transmission Solenoid/TRS Assembly per the Service Information. Note: Do NOT replace the entire Valve Body. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE/TRANS SOLENOID/TRS ASSY - REMOVAL) Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) 5. CHECK THE (T259) 4C SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT

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?YesRepair the (T259) 4C Solenoid Control circuit for a short to another circuit(s).Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoGo To 66. CHECK THE (T259) 4C SOLENOID CONTROL CIRCUIT FOR AN OPEN

Connect Miller tool #8815 to the PCM C4 harness connector.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 between the Transmission Solenoid/TRS Assembly harness connector and the appropriate terminal of Miller tool #8815.Is the resistance above 5.0 ohms?YesRepair the (T259) 4C Solenoid Control circuit for an open.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoGo To 77. CHECK THE (T259) 4C SOLENOID CONTROL CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between ground and the (T259) 4C Solenoid Control circuit.Is the resistance below 5.0 ohms?YesRepair the (T259) 4C Solenoid Control circuit for a short to ground.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoUsing 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. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)