GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0975: Shift Solenoid (SS) 2 Control Circuit Open

DTC P0976: Shift Solenoid (SS) 2  Control Circuit Low Voltage

DTC P0977: Shift Solenoid (SS) 2 Control Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Control

P0976

P0975

P0977

--

Typical Scan Tool Data

Shift Solenoid 2

Display Parameters

Normal Range

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Engine running, cycle gear shift selector through all ranges

Shift Solenoid 2

On or Off

Off

Off

Off

Circuit/System Description

Shift solenoid 2 (SS2) is a normally closed (N/C) solenoid that provides control main pressure to stroke shift valve 2. The transmission control module (TCM) determines the proper solenoid command logic to move shift valve 2 to attain a particular range. The TCM provides B+ to pressure control solenoid 2 (PCS2), and shift solenoids 1, 2, and 3 (SS1, SS2, and SS3) through a separate solid state device called high side driver 2 (HSD2). The TCM uses a low side driver to switch SS2 ON and OFF. Since the shift valve position is critical in determining the correct transmission range, a pressure switch located in the pressure switch manifold provides feedback to the TCM on the position of the valve.

Conditions for Running the DTC

P0975-P0977

    • Ignition is ON.
    • Ignition voltage is greater than 9.0 V and less than 18 V.
    • Engine running for greater than 5 seconds.

Conditions for Setting the DTC

P0975

This DTC sets when the TCM detects an open circuit on the SS2 control circuit for greater than 1 second.

P0976

This DTC sets when the TCM detects a short to ground on the SS2 control circuit for greater than 1 second.

P0977

This DTC sets when the TCM detects a short to voltage on the SS2 circuit for greater than 1 second.

Action Taken When the DTC Sets

P0975-P0977

    • The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
    • If the fault occurs while in a forward range, a shift to 1st, 3rd, or 5th range is made.
    • While diagnostic response is active, if the shift selector is moved to NEUTRAL, the transmission will shift to NEUTRAL. If the shift selector is moved to REVERSE, the transmission will shift to REVERSE. If the shift selector is moved to a forward range or to REVERSE and the transmission is compromised by overspeeding or direction change, the transmission will shift to NEUTRAL.
    • DTC P0975, P0976, or P0977 is stored in TCM history.
    • Main modulation (MAIN MOD) is inhibited.
    • The TCM freezes shift adapts.
    • The TCM inhibits torque converter clutch (TCC) engagement.

Conditions for Clearing the DTC

DTCs P0975, P0976, and P0977 are Type A DTCs.

Diagnostic Aids

P0975

    • You may have to drive the vehicle in order to experience a condition.
    • DTC P0975, set in combination with DTC P0964, P0975, and P0979, may indicate an open in the HSD2 circuit.

P0976 and P0977

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

    •  Transmission General Description
    •  Transmission Component and System Description
    •  Electronic Component Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

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 Shift Solenoid 2 ON and OFF with a scan tool. Observe the operation of the Shift Solenoid 2 parameter. The Shift Solenoid 2 parameter should turn On and Off.
  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 N and ground.
  3. 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.
  4. Connect a test lamp between the control circuit terminal B and the B+ circuit terminal N.
  5. Command the Shift Solenoid 2 ON and OFF with a scan tool and verify the Shift Solenoid 2 parameter changes from On to Off. The test lamp should turn ON and OFF when changing between the commanded states.
  6. 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.
  7. Remove the transmission oil pan. Refer to Oil Pan Replacement.
  8. Test the transmission internal SS2, B+, and control circuits for a short to voltage, short to ground, or an open/high resistance.
  9. If the circuits test normal, test or replace the SS2 solenoid.

Component Testing

Static Testing

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

  1. Ignition OFF, remove the SS2 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 SS2. Refer to Temperature Versus Resistance.
  3. If not within the specified range, replace the SS2.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Wiring Harness Replacement
    •  Control Valve Solenoid Replacement
    •  Control Module References for TCM replacement, setup, and programming

Repair Verification

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