For 1990-2009 cars

### DTC P0766 - Shift Solenoid 4 Control Circuit Low Voltage

### Circuit Description

Shift solenoid 4 is used to supply and relieve fluid pressure to the 4th gear clutch pack. Shift solenoid 4 is turned electrically ON/hydraulically OFF (relieving pressure to 4th gear clutch) during 1st , 2nd and 3rd gear operation. The powertrain control module (PCM) controls shift solenoid 4 by controlling an internal driver that pulls the solenoid circuit to ground. During normal 4th gear shift operation, the PCM will turn OFF, open the driver, shift solenoid 4 and keep it OFF until a downshift occurs. The PCM will PWM the pressure control solenoid to adapt shift timing. The shift solenoid 4 circuit is monitored for low and high voltage faults. DTC P0766 sets when shift solenoid 4 is commanded OFF and the feedback voltage at the PCM is low.

### DTC Parameters

DTC P0766 will set if shift solenoid 4 feedback voltage is less than 1.25 volts with shift solenoid 4 commanded OFF when:

• | The condition exists for longer than 100 milliseconds (2001)*.

• | The condition exists for longer than 100 milliseconds, solenoid is turned Off for 1 minute, then condition exists again for longer than 100 milliseconds (2000).

• | The fuel pump relay is commanded ON.

DTC P0766 diagnostic runs continuously with fuel pump relay commanded ON and shift solenoid 4 commanded OFF.

DTC P0766 is a type D DTC.

*Applicable to vehicles built after June 2000.

### Diagnostic Aids

To locate an intermittent problem, use scan tool to command TRANS. SOLENOID POWER On, while monitoring the SHIFT SOL. 4 - LOW VOLT or SHIFT SOL. 4 - OPEN test. When a fault, open or short to ground exists, the scan tool will display TEST FAIL for both tests.

The tests will fail only when the device is being commanded OFF and the voltage at the PCM is low. The tests update every 100 milliseconds whenever the ignition is turned ON and the device is being commanded OFF via the scan tool or PCM.

Shift solenoid 4 resistance: 3.8-7.2 ohms

Nominal value: 4.5 ohms at 68°F