GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 CTS 🢒 DTC 🢒 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

Diagnostic Fault Information

The following fault table will help determine if a hydraulic circuit or an incorrect position or application of a component affects the transmission operation.

Component

Cause

DTCs

Lower Control Valve Body

Clutch select valve 2 stuck - debris, sediment, binding or scored bore

P0751

Control Solenoid (w/body and TCM) Valve Assembly

Clutch Pressure Control Solenoid 2:

    • Not exhausting - Stuck OFF
    • Needle piston or armature pin binding
    • Control signal fluid supply leak - valve body filter plate assembly cracked or damaged gasket seal
    • O-ring seals leaking

P0751

Circuit/System Description

The shift solenoid (SS) 1 is part of the control solenoid (w/body and TCM) valve assembly. The assembly is attached to the lower control valve body and has no serviceable parts. The solenoid operates by the TCM opening or closing the ground circuit. With the solenoid circuit grounded (solenoid on), the internal plunger and metering ball block the exhaust fluid creating signal fluid pressure. The signal fluid acts against the clutch select valve 2 to overcome the valve spring force moving it to the apply position, allowing the shift. The TCM shifts the transmission by operating the solenoids in on/off combinations.

Conditions for Running the DTC
    • Input speed is less than 50 RPM.
    • Vehicle speed is less than 25 km/h (16 mph).

Conditions for Setting the DTC
    • First gear locked, engine braking is commanded.
    • Commanded gear slip is equal to or less than 100 RPM for 0.125 second.

Action Taken When the DTC Sets

Depending when the vehicle was manufactured, DTC P0751 is either a Type A or Type B DTC.

Conditions for Clearing the DTC

Depending when the vehicle was manufactured, DTC P0751 is either a Type A or Type B 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.
    • Look for a non-pressurized TFP switch 5 while in first gear. If so, inspect for a stuck off clutch select valve 2.
    • Use the scan tool to view the TFP Switch status and refer to the Transmission Fluid Pressure Switch Logic table to determine when a TFP switch should be active or inactive for a given gear. This will help determine if the hydraulic circuit is functioning and if the shift solenoid or the valve train is in an incorrect position.
    • Under certain conditions where P0751 sets, the TCM provides functional status to other control modules. This may result in the module disabling the cruise control. For this condition, correct the DTC and then power-down to reset the TCM.

Reference Information

Schematic Reference

Drive Range, First Gear Engine Braking

Description and Operation

Transmission Component and System Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

DT-47825 Control Solenoid Test Plate

Circuit/System Verification
  1. Perform the Transmission Fluid Check . The fluid must be full and in good condition.
  2. Start engine in park and wait a moment. Shift to Reverse, pause, and then shift to Drive (D6) without allowing the vehicle to move.
  3. View scan tool parameters Commanded Gear and Gear Ratio.
  4. 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) or more at least 2 times.
  5. Make certain the 1-2 shift is attainable and occurs as expected. Use the two scan tool parameters and refer to the Shift Solenoid Valve State and Gear Ratio table to verify the correct ratio for the commanded gear.

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 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.
    ⇒If the control solenoid (w/body and TCM) valve assembly shift solenoid functions correctly, inspect the lower control valve body assembly for the following:
    • Clutch select solenoid valve and valve body bore for scratches, gouges, scuffing, scoring, and sediment.
    • The valve should move freely in the bore without stopping or binding.
    • Inspect clutch select valve 2 (CSV2) fluid circuits for blockage.
    • Inspect the clutch select valve spring for damage, distortions, or broken coils.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Replace the control solenoid (w/body and TCM) valve assembly. Refer to Control Module References for replacement, setup, or programming.
  2. Perform the Service Fast Learn Adapts if internal transmission repairs are performed.