GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Equinox 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - AF33-5 🢒 DTC P0115, P0120, P0703, P0727, P0826, P1779, P2544, or P2637

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 Descriptors

DTC P0115: Engine Coolant Temperature (ECT) Sensor Circuit

DTC P0120: Throttle Position (TP) Sensor Circuit

DTC P0703: Brake Switch Circuit

DTC P0727: Engine Speed - No Signal

DTC P0826: Up and Down Shift Switch Circuit

DTC P1779: Torque Delivered Signal

DTC P2544: Transmission Torque Request Circuit

DTC P2637: Transmission Torque Delivered Circuit

Circuit/System Description

The automatic transmission control module (TCM) receives transmission related information from the engine control module (ECM) via serial data. When the ECM receives "invalid" transmission related information, it notifies the TCM. The TCM then sets the appropriate DTC.

Conditions for Running the DTC
    • No Lost Communications with the ECM, DTC U0100.
    • The ignition in ON for at least 3 seconds.
    • Not in Emergency Mode.

Conditions for Setting the DTC

P0115

The TCM detects that the engine coolant temperature signal to the ECM is invalid.

P0120

The TCM detects that the accelerator position signal to the ECM is invalid.

P0703

The TCM detects that the brake pedal signal to the ECM is invalid.

P0727

The TCM detects that the engine speed signal to the ECM is invalid.

P0826

The TCM detects that the Tap Up/Down mode request or switch status signal to the ECM is invalid.

P1779

The TCM detects that the engine air flow torque steady state signal to the ECM is invalid.

P2544

The TCM detects that the Transmission Torque Request Circuit signal to the ECM is invalid.

P2637

The TCM detects that the engine torque signal to the ECM is invalid.

Action Taken When the DTC Sets

P0115

    • DTC P0115 is a Type D DTC.
    • The transmission will default the engine coolant temperature to 80°C (176°F).

P0120

    • DTC P0120 is a Type D DTC.
    • The TCM will default Accelerator Position data to 0 percent.
    • The transmission will operate in 5th gear in D or M range, 2nd gear in L range.

P0703

    • DTC P0703 is a Type D DTC.
    • The TCM will default the brake pedal signal to off.

P0727

    • DTC P0727 is a Type D DTC.
    • The TCM will default engine speed data to 6000 RPM.
    • The TCM will limit engine torque to 270 N·m (199 lb ft).
    • The transmission will operate in 5th gear in D or M range, 2nd gear in L range.

P0826

    • DTC P0826 is a Type D DTC.
    • The transmission will disable or inhibit Tap Up/Down mode.

P1779

    • DTC P1779 is a Type D DTC.
    • The TCM will default driver requested torque data to 300 N·m (221 lb ft).

P2544

    • DTC P2544 is a Type D DTC.
    • The TCM will increase transmission oil pressure to maximum.
    • The TCM will limit the maximum shift speed to 4000 RPM.

P2637

    • DTC P2637 is a Type D DTC.
    • The TCM will default engine torque data to 300 N·m (221 lb ft).
    • The TCM will limit engine torque to 270 N·m (199 lb ft).
    • The transmission will operate in 5th gear in D or M range, 2nd gear in L range.

Conditions for Clearing the DTC

DTC P0115, P0120, P0703, P0727, P0826, P1779, P2544 and P2637 are Type D DTCs.

Reference Information

Description and Operation

Electronic Component Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Verification

Important: Correct any Engine Controls DTCs before diagnosing TCM DTCs.

DTC P0115, P0120, P0703, P0727, P0826, P1779, P2544, and P2637 are informational DTCs. Refer to Diagnostic Trouble Code (DTC) List - Vehicle for diagnosis of ECM DTCs.