For 1990-2009 cars

### DTC P0789 - Shift / Timing Solenoid Control Circuit Intermittent

### Circuit Description

### Conditions for Running the DTC

The pressure control (PC) solenoid, torque converter clutch (TCC) solenoid, shift solenoid 2, shift solenoid 3 and shift solenoid 4 regulate the amount of fluid that is applied to the main line, torque converter clutch and each of the three clutch packs. Each solenoid is independently controlled by the powertrain control module (PCM) through separate internal drivers which pull the solenoid circuit to ground. All of the solenoids are supplied ignition voltage whenever the PCM commands the fuel pump relay ON. Each solenoid is monitored by the PCM for low and high voltage faults. DTC P0789 sets when an intermittent open, short to ground or short to voltage occurs in any one of the 5 solenoids, which is not long enough to set a low or high circuit fault DTC.

### DTC Parameters

DTC P0789 will set if any one of the 5 transaxle solenoid circuits is intermittently open, shorted to ground or shorted to voltage when:

• | The condition exists between 20-100 milliseconds

• | The engine is running

This DTC will set when a transaxle solenoid circuit fails for a very short amount of time, in which the PCM cannot detect which specific fault has occurred.

DTC P0789 diagnostic runs continuously with engine running.

DTC P0789 is a type D DTC.

### Diagnostic Aids

Important: If a specific transaxle solenoid low or high circuit fault DTC is set, that circuit is most likely the cause of DTC P0789 and should be diagnosed first.

To locate this intermittent problem use scan tool to command TRANS. SOLENOID POWER On, while monitoring each of the five solenoids LOW VOLT and OPEN tests with ignition ON, engine OFF.

When an open or short to ground fault exists, the scan tool will display TEST FAIL for that specific solenoid LOW VOLT and OPEN tests.

If all the above tests pass, use scan tool to command each solenoid ON (PWM) by performing the SOLENOID AUDIBLE CHECK. When a short to voltage or shorted solenoid exists, the solenoid will stop cycling.

The LOW VOLT and OPEN tests will fail only when the device is being commanded OFF and the voltage at the PCM is low. The HIGH VOLT test will fail only when the device is being commanded ON and the voltage at the PCM is high. All three tests update every 100 milliseconds when commanded via the scan tool or PCM.

All transaxle solenoid resistances: 3.8-7.2 ohms

Nominal value: 4.5 ohms at 68°F