Diagnostic Instructions
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 3- 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 attempting first gear engine braking, if first gear ratio is not achieved in a predetermined period of time and the closest
gear ratio detected is fourth, the TCM will command second gear. 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 vehicle speed is 25 km/h (16 mph) or less. |
| • | First gear locked is commanded. |
| • | The closest gear ratio is 4th gear. |
Conditions for Setting the DTC
Commanded gear equals first lock and 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 B DTC. |
| • | The TCM inhibits 1st gear. |
Conditions for Clearing the DTC
DTC P0751 is a 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. |
| • | 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 to determine if the hydraulic circuit functioning
and if the shift solenoid or the valve train is in an incorrect position. |
Reference Information
Schematic Reference
Drive Range, First Gear Engine Braking
Connector End View Reference
Component Connector End Views
Description and Operation
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Special Tools
Circuit/System Verification
- Perform the
Transmission Fluid Check
.
- 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.
| ⇒ | If the DTC resets, go to Circuit/System Testing. |
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Perform the
Line Pressure Check
.
| ⇒ | If the pressure is out of specification correct that concern first. |
- Perform the
Control Solenoid Valve and Transmission Control Module Assembly Cleaning
and retest the DTC as outlined in the Circuit/System Verification steps.
| ⇒ | If the DTC resets, continue on with testing. |
- Perform the
Control Solenoid Valve and Transmission Control Module Assembly Inspection
.
| ⇒ | If a concern is found, repair or replace the control solenoid (w/body and TCM) valve assembly. |
- Perform the
Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test
.
| ⇒ | 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.
| • | Refer to
Control Module References
for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming. |
