Diagnostic Instructions
DTC Descriptor
DTC P1751: Shift Valve 1 Performance
Diagnostic Fault Information
The following fault table gives examples of how hydraulic circuit problems and malfunctioning hard parts affect the transmission operation.
Component
| Cause
| DTCs
|
Automatic Transmission Fluid Pump Cover Assembly
| TCC control valve stuck in fluid pump cover assembly
| P1751
|
Control Solenoid (w/body and TCM) Valve Assembly
| Shift Solenoid 1:
• | Always exhausting - Stuck On |
• | 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 |
• | Control valve body spacer plate assembly number 4 ball check valve orifice damaged or burred |
| P1751
|
Circuit/System Description
The shift valve 1 (clutch select valve 2) is part of the lower control valve body. The shift valve 1 (clutch select valve 2) controls fluid to the R1 and 4-5-6 clutches. During this diagnostic test, intrusive actions are taken
by the transmission control module (TCM) to test the clutch select valve 2 to see if the valve is stuck. The TCM commands the shift solenoid (SS) 1 ON to put pressure on the valve towards the spring and at the same time, elevates line pressure
slightly to assist the spring side pressure. If the spring is broken, the valve will slip back towards the spring indicating a mechanical failure and the DTC will set.
Conditions for Running the DTC
• | No ISS DTCs P0716 or P0717. |
• | No OSS DTCs P0722 or P0723. |
• | No TCC Performance DTCs P0741 or P0742. |
• | No TCC Electrical DTCs P2763, P2763, or P2764. |
• | DTC 1751 has not failed this ignition cycle. |
• | The engine run time is greater than 5 seconds. |
• | The ignition voltage is between 8.6 volts and 19.0 volts. |
• | The transmission fluid temperature (TFT) is 20-130°C (68-266°F). |
• | The calc. throttle position is 8 percent or greater. |
• | The engine torque is greater than 80 N·m (59 lb ft). |
• | No upshift or downshift in process. |
• | The attained gear slip is equal to or greater than 100 RPM. |
• | The TCC is commanded OFF. |
• | Vehicle speed is greater than 16 km/h (20 mph). |
• | The TISS is equal to or greater than 1,100 RPM. |
• | Commanded gear is 2nd or greater. |
• | The gear ratio is between 0.69-1.97. |
Conditions for Setting the DTC
The TCM detects attained gear slip is 150 RPM or greater for 0.5 second 5 times during the same ignition cycle.
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.
Diagnostic Aids
• | DTC P1751 detects gear box slip when the mode 2 valve solenoid is commanded on as part of the P0742 TCC stuck OFF test. |
• | 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
Component Connector End Views
Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Perform the
Transmission Fluid Check
.
- While operating the vehicle in drive with the calculated throttle position greater than 8 percent and the attained gear slip less than 1,100 RPM, command the TCC is commanded ON and OFF a minimum of 5 times.
⇒ | If the DTC resets, go to Component Testing. |
- Operate the vehicle within the Conditions 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
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 this concern first. |
- Perform the
Control Solenoid Valve and Transmission Control Module Assembly Cleaning
procedure in an attempt to clean or free up a potential sticking valve of dirt or debris. Retest the DTC as outlined in
the Circuit/System Verification steps.
- Perform the
Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test
.
⇒ | If the SS 1 is found to be leaking or stuck, 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 valve 2 (CSV2) and valve body bore for scratches, gouges, scuffing, scoring, debris, or damage. The valve should move freely in the bore without stopping or binding. |
⇒ | If you found a valve body concern, repair or replace the lower control valve body as necessary. |
• | Inspect the CSV2 fluid circuits for blockage. |
• | Inspect the CSV2 valve spring for damage, distortions, or broken coils. |
- Inspect the TCC control valve in the pump cover assembly.
⇒ | If you found a TCC control valve concern, repair or replace the TCC control valve or pump as necessary. |
- Inspect the torque converter assembly for damage or discoloration.
⇒ | If you found a torque converter assembly concern, replace the torque converter assembly as necessary. |
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. |