GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 SLS 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 6L50/6L80/6L90 🢒 DTC P0751

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 P0751:  Shift Solenoid (SS) 1 Valve Performance - Stuck Off

Circuit/System Description

The shift solenoid (SS) valve 1 is part of the lower control valve body. The SS valve 1 is a normally closed (NC) solenoid valve and controls fluid to the clutch select valve 2 and related clutches. During this diagnostic test, intrusive actions are taken by the transmission control module (TCM) to test the SS valve 1 to see if the valve is stuck OFF. When in first gear engine braking, if first gear ratio is not achieved in a predetermined period of time and the closest gear ratio detected if fourth, the TCM commands second gear and if second gear ratio is attained this indicates a stuck OFF SS valve 1 and the DTC will set.

Conditions for Running the DTC
    • The transmission input shaft speed is less than 50 RPM.
    • The vehicle speed is less than 25 km/h (15.6 mph).

Conditions for Setting the DTC

The TCM detects a commanded gear equals first lock, the latest gear ratio equals fourth and gear box slip is less than 100 RPM for 0.125 seconds

Action Taken When the DTC Sets

DTC P0751 is a type C DTC.

Conditions for Clearing the DTC

DTC P0751 is a type C DTC.

Diagnostic Aids

When attempting to set transmission performance DTCs, observe the Freeze Frame and Failure Records to assist in duplicating the failure conditions. Ensure the transmission fluid level is correct and there are no leaks.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

    •  Automatic Transmission Inline 16-Way Connector End View
    •  Automatic Transmission Internal Connector End Views
    •  Automatic Transmission Related Connector End Views

DTC Type Reference

    •  Diagnostic Trouble Code (DTC) Type Definitions
    •  Diagnostic Trouble Code (DTC) List/Type

Electrical Information Reference

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

Special Tools

DT-47825 Control Solenoid Test Plate

Circuit/System Verification
  1. Perform the Transmission Fluid Check .
  2. Operate the vehicle in drive from a complete stop, with the calculated throttle position greater than 15 percent to obtain 56 km/h (35 mph) 2 times.
    3. ⇒If the DTC resets, go to Circuit/System Testing.

Circuit/System Testing
  1. Perform the Line Pressure Check .
    2. ⇒If the pressure is out of specification correct that concern first.
  2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Cleaning and retest the DTC as outlined in the Circuit/System Verification steps.
    3. ⇒If the DTC resets, continue on with testing.
  3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection .
    4. ⇒If a concern is found, repair or replace the control solenoid (w/body and TCM) valve assembly.
  4. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test .
    5. ⇒If the shift solenoid 1 is found to be leaking or stuck OFF, replace the control solenoid (w/body and TCM) valve assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Service Fast Learn Adapts
    •  Control Module References for TCM replacement, setup, or programming