6T30/6T40/6T45/6T50 - Automatic Transmission (Gen 2)

DTC P0751 or P0752 (Gen 2 with 2.4 L - LEA)

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 Descriptors

DTC P0751
- Shift Solenoid 1 Valve Performance - Stuck Off

DTC P0752
- Shift Solenoid 1 Valve Performance - Stuck On

Circuit/System Description

The shift solenoid valve 1 is part of the control solenoid valve assembly, which has no serviceable components. The shift solenoid valve 1 is a normally closed (NC) solenoid valve and controls fluid pressure to the clutch select valve. When shift solenoid valve 1 is commanded on, fluid pressure acts on the clutch select valve, moving the valve to another position. Fluid from the R1/4-5-6 regulator valve flows though the clutch select valve and is directed to either the low and reverse clutch or the 4-5-6 clutch, depending on the position of the clutch select valve.

Conditions for Running the DTC

* DTC P0101, P0102, P0103, P0106, P0107, P0108, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0401, P042E, P0716, P0717, P0722, P0723, or P182E is not set.

* Transmission fluid temperature (TFT) is -6.6°C (20°F) or greater.

* Engine speed is between 400-7500 RPM for 5 seconds.

* Output shaft speed is greater than 0 RPM, or the throttle is greater than 0.5 percent.

* Ignition voltage is between 9-32 V.

* Shift is complete.

* Engine torque signal is valid.

* Throttle position signal is valid.

* High-Side driver is enabled.

Conditions for Setting the DTC

P0751

Transmission control module (TCM) detects gear slip greater than 400 RPM for 1.5 seconds with 1st gear commanded and the closest gear ratio is 4th gear. This must occur 8 times.

P0752

TCM detects gear slip greater than 400 RPM for 1.5 seconds when 3rd gear is commanded. This must occur 5 times.

Action Taken When the DTC Sets

P0751

* DTC P0751 is a type B DTC.

* TCM inhibits 1st gear.

* TCM inhibits Neutral idle.

P0752

* DTC P0752 is a type A DTC.

* TCM limits the transmission to 2nd range and reverse.

* TCM inhibits Tap Up/Down function.

* TCM inhibits manual shifting of forward gears.

* TCM disables neutral idle.

* TCM freezes adapts.

* TCM commands maximum line pressure.

Conditions for Clearing the DTC

P0751

DTC P0751 is a type B DTC.

P0752

DTC P0752 is a type A DTC.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics 6T30/6T40/6T45/6T50 - Automatic Transmission

Connector End View Reference

* Component Connector End Views Sunshade - Left Front

* Inline Harness Connector End Views X110

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

* Drive Range, First Gear Engine Braking (Gen 2/Hybrid) Drive Range, First Gear Engine Braking (Gen 2/Hybrid)

* Drive Range, Third Gear (Gen 2/Hybrid) Drive Range, Third Gear (Gen 2/Hybrid)

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

Special Tools

DT-48616 - Solenoid Assembly Test Kit & Adapter Harness

For equivalent regional tools, refer to Special Tools 6T30/6T40/6T45/6T50 - Automatic Transmission.

Circuit/System Verification

Note: If other DTCs are set, diagnose those DTCs first.

1. Engine idling in Park position, with parking brake applied and drive wheels chocked.

2. Verify the transmission fluid level and condition is correct. Refer to Transmission Fluid Level and Condition Check 6T30/6T40/6T45/6T50 - Automatic Transmission.

3. Ignition ON, clear the TCM DTCs with a scan tool.

4. From a stop, accelerate to 72 km/h (45 mph) with the calculated throttle position greater than 15 percent. Perform this test 8 times. DTCs P0751 or P0752 should not set.

• If DTC P0751 or P0752 sets
Refer to Circuit/System Testing.

• If DTC does not set

5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

6. Verify the DTC does not set.

• If a DTC sets
Refer to Circuit/System Testing.

• If DTC does not set

7. All OK.

Circuit/System Testing

1. Engine idling at the normal operating temperature.

2. Verify the transmission line pressures are within the specified ranges. Refer to Line Pressure Check Line Pressure Check and Solenoid Valve Pressure (Gen 2) Solenoid Valve Pressure (Gen 2).

• If line pressure is not within the specified ranges
Refer to Fluid Pressure High or Low Fluid Pressure High or Low.

• If line pressure is within the specified ranges

3. Ignition OFF, remove the Q8 control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement 6T30/6T40/6T45/6T50 - Automatic Transmission.

4. Verify a pressure change occurs for all solenoids when performing the solenoid test. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test.

• If a pressure change does not occur
Replace the Q8 control solenoid valve assembly.

• If a pressure change does occur

5. Verify the mechanical conditions listed below do not exist. Repair or replace as necessary.

P0751 - Control Valve Body

* Clutch select valve bore plug undersized. Plug should be a valve fit in the bore.

* Check ball #1 missing, damaged/malformed.

* Seat for check ball #1 damaged or leaking.

P0751 or P0752 - Control Valve Body

* Clutch select valve stuck from debris, sediment, binding, or a scored bore.

* Low and reverse and 4-5-6 clutch regulator valve stuck or sticking from debris, sediment, binding, or a scored bore.

P0751 or P0752 - Channel Plate and Spacer Plate

Oil channels or orifices blocked by debris.

P0751 or P0752 - Q8 Control Solenoid Valve Assembly

* Not pressurizing due to shift solenoid valve 1 being stuck OFF or leaking.

* Pressure not exhausting due to shift solenoid valve 1 being stuck ON.

* Control signal fluid supply leak due to valve body filter plate assembly cracked, blocked, or damaged gasket seal.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Perform the Transmission Adaptive Values Learn 6T30/6T40/6T45/6T50 - Automatic Transmission following all transmission related repairs.

* Refer to Control Module References Programming and Relearning for control solenoid valve assembly replacement, programming and setup.