P1751
DTC P1751
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P1751
- Shift Valve 1 Performance
Circuit/System Description
The shift solenoid (SS) 1 is part of the control solenoid valve assembly, which has no serviceable parts. SS 1 provides fluid pressure to control the operation of the clutch select valve 2, which is located in the control valve lower body assembly. SS 1, in conjunction with clutch select valve 2, controls fluid to the R1 and 4-5-6 clutches. A diagnostic test is performed by the transmission control module (TCM) to determine the state of the clutch select valve 2. During this diagnostic test, the TCM commands the SS 1 ON, supplying pressure to move the clutch select valve 2 toward its spring. At the same time, line pressure is elevated slightly to assist the spring side pressure. If the spring is broken, or the clutch select valve 2 cannot move due to another mechanical condition the DTC will set.
Conditions for Running the DTC
* DTCs P0716, P0717, P0722, P0723, P0741, P0742, P1751, P2762, P2763, or P2764 are not set.
* The engine speed is 500 RPM or greater for 5 seconds or greater.
* The transmission fluid temperature (TFT) is 20-130°C (68-266°F).
* The calculated throttle position is between 8-90 percent.
* The engine torque is greater than 50 Nm (36 lb ft).
* No upshift or downshift in process.
* The attained gear slip is 70 RPM or greater.
Conditions for Setting the DTC
The TCM detects attained gear slip is 75 RPM or greater for 1 second.
Action Taken When the DTC Sets
DTC P1751 is a Type B DTC.
Conditions for Clearing the DTC
* DTC P1751 is a Type B DTC.
* The TCM freezes transmission adaptive functions.
Diagnostic Aids
Before performing a road test, configure and setup the scan tool for snapshot mode. This will allow you to display, monitor, and verify multiple transmission data parameters at one time, after the road test.
Reference Information
Connector End View Reference
* Component Connector End Views (Connector Views)
* Inline Harness Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Description and Operation
* Electronic Component Description (Electronic Component Description)
* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Park - Engine Running (Park - Engine Running)
* Reverse (Reverse)
* Neutral - Engine Running (Neutral - Engine Running)
* Drive Range, First Gear Engine Braking (First Gear Engine Braking)
* Drive Range, First Gear (First Gear)
* Drive Range, Second Gear (Second Gear)
* Drive Range, Third Gear (Third Gear)
* Drive Range, Third Gear Default (Third Gear Default)
* Drive Range - Fourth Gear (Fourth Gear)
* Drive Range, Fifth Gear (Fifth Gear)
* Drive Range, Fifth Gear Default (Fifth Gear Default)
* Drive Range, Sixth Gear (Sixth Gear)
* Fluid Passages (Fluid Passages)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Note: If other DTCs are set, diagnose those DTCs first.
1. Engine idling in Park, with parking brake applied and drive wheels chocked.
2. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check) to verify correct fluid level and condition.
Note: Perform a scan tool snapshot, during the road test.
3. Perform the Road Test (Road Test). Verify the transmission operation performs as indicated in the road test instructions.
4. Review the scan tool snapshot transmission data parameters. Verify the engine and transmission data parameters display the correct values in all forward gear ranges:
* Engine Speed
* Vehicle Speed
* Transmission ISS
* Transmission OSS
* Shift Solenoid Valve 1
* Gear Command
5. Operate the vehicle within the Condition 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. Perform the Line Pressure Check (Line Pressure Check). Verify the transmission line pressures are within the specified ranges.
• If not within the specified ranges, refer to Fluid Pressure High or Low (Fluid Pressure High or Low).
2. Ignition OFF, remove the Q8 control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement (Service and Repair).
3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test (Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test).
• If the Q8 control solenoid valve assembly does not pass the performance test, replace the Q8 control solenoid valve assembly.
4. Listed in the chart below, are conditions for each component that could set DTC P1751. Carefully inspect each component for that condition. Repair or replace as necessary.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Replace the control valve body. Refer to Control Valve Lower Body and Upper Body Replacement (Control Valve Lower Body and Upper Body Replacement).
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.