Diagnostic Instructions

DTC Descriptors

DTC P0960: Main Modulation/Line Pressure Control (PC) Solenoid Control Circuit Open

DTC P0962: Main Modulation/Line Pressure Control (PC) Solenoid Control Circuit Low Voltage

DTC P0963: Main Modulation/Line Pressure Control (PC) Solenoid Control Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Control	P0962	P0960	P0963	--

Circuit/System Description

Main Modulation/Line Pressure Control (MAIN MOD) Solenoid is a normally closed (N/C) solenoid that regulates transmission line pressure. This solenoid is used to reduce line pressure when the vehicle is not moving with engine at idle, thus decreasing engine load and also improving cooler flow. The transmission control module (TCM) commands the MAIN MOD solenoid ON when specific transmission and engine conditions are met. When the MAIN MOD solenoid is commanded ON, control main pressure is routed to the main regulator valve lowering the line pressure.

The TCM provides B+ to the MAIN MOD solenoid, torque converter clutch (TCC) pressure control solenoid, and pressure control solenoid 1 (PCS1) through a separate solid state device called high side driver 1 (HSD1). The TCM uses a low side driver to switch the MAIN MOD solenoid ON and OFF.

Conditions for Running the DTC

Conditions for Setting the DTC

P0960

This DTC sets when the TCM detects an open circuit on the MAIN MOD control circuit for greater than 5 seconds.

P0962

This DTC sets when the TCM detects a short to ground on the MAIN MOD control circuit for greater than 5 seconds.

P0963

This DTC sets when the TCM detects a short to voltage on the MAIN MOD circuit for greater than 5 seconds.

Action Taken When the DTC Sets

P0960

P0962 or P0963

Conditions for Clearing the DTC

DTCs P0960, P0962, and P0963 are Type A DTCs.

Diagnostic Aids

P0960

P0962 or P0963

You may have to drive the vehicle in order to experience a condition.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, engine OFF. Command the Modulated Main Pres. Ctrl. Sol. ON and OFF with a scan tool. The Line PC Sol. Pressure Command parameter should change from 0 kPa (0 psi) to 1600 kPa (232 psi).
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the X175 harness connector at the transmission.
2. Ignition ON, engine OFF. Verify that a test lamp illuminates between the B+ circuit terminal L and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TCM.

3. Connect a test lamp between the control circuit terminal S and the B+ circuit terminal L.
4. Command the Modulated Main Pres. Ctrl. Sol. ON and OFF with a scan tool and verify the Line PC Sol. Pressure Command parameter changes from 0 kPa (0 psi) to 1600 kPa (232 psi). The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the TCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the TCM.

5. Remove the transmission oil pan. Refer to Oil Pan Replacement.
6. Test the transmission internal B+ and control circuits for a short to voltage, short to ground, or an open/high resistance.

⇒	If the circuits test normal, test or replace the MAIN MOD solenoid.

Component Testing

Static Testing

Note: You must perform the Circuit/System Testing first.

1. Ignition OFF, remove the MAIN MOD solenoid from the valve body. Refer to Control Valve Solenoid Replacement.
2. Test for resistance between the control circuit terminal B, and the B+ circuit terminal A of the MAIN MOD solenoid. Refer to Temperature Versus Resistance.

⇒	If not within the specified range, replace the MAIN MOD solenoid.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Repair Verification

If another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.