2/22/2021 DTC P0751 or P0752 • 2008 Cadillac CTS • MotoLogic
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DTC P0751 or P0752
Applies to:
6L50/6L80/6L90
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
Note: The DTCs listed below set due to a transmission hydraulic/mechanical condition. Perform the Circuit/System
Verification and Circuit/System Testing to identify the cause.
DTC P0751
Shift Solenoid (SS) 1 Valve Performance – Stuck OFF – Transmission Hydraulic/Mechanical Performance
DTC P0752
Shift Solenoid (SS) 1 Valve Performance – Stuck ON – Transmission Hydraulic/Mechanical Performance
Circuit/System Description
The shift solenoid (SS) 1 is part of the control solenoid valve assembly which has no serviceable parts. The control
solenoid valve assembly is attached to the lower control valve body. 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
P0751 or P0752
DTCs P0121, P0122, P0123, P0716, P0717, P0722, P0723, and P0182E are not set.
Ignition voltage is 8.6 V or greater.
The engine speed is 500 RPM or greater for 5 seconds.
The IMS range is not PARK, NEUTRAL or REVERSE.
High Side Driver (HSD) is enabled.
The transmission fluid temperature is 0–130°C (32–266°F).
Accelerator pedal position signal is valid.
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2/22/2021 DTC P0751 or P0752 • 2008 Cadillac CTS • MotoLogic
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The throttle position signal is valid.
The output shaft speed is 0 RPM or greater.
The TCM must receive a valid torque signal from the ECM.
Conditions for Setting the DTC
P0751
Commanded gear slip is 200 RPM for 1.1 seconds.
First gear locked is commanded.
The closest gear ratio is 4th gear.
P0752
Gear slip is 200 RPM or greater for 5 seconds.
Commanded gear is 3rd.
Transmission has achieved second gear.
Action Taken When the DTC Sets
DTC P0751 is a Type B DTC.
DTC P0752 is a Type A DTC.
Conditions for Clearing the DTC
DTC P0751 is a Type B DTC.
DTC P0752 is a Type A DTC.
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
Schematic Reference
Automatic Transmission Controls Schematics
Description and Operation
Electronic Component Description
Transmission General Description
Transmission Component and System Description
Park - Engine Running
Reverse
Neutral - Engine Running
Drive Range, First Gear Engine Braking
Drive Range, First Gear
Drive Range, Second Gear
Drive Range, Third Gear
Drive Range, Third Gear Default
Drive Range - Fourth Gear
Drive Range, Fifth Gear
Drive Range, Fifth Gear Default
Drive Range, Sixth Gear
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2/22/2021 DTC P0751 or P0752 • 2008 Cadillac CTS • MotoLogic
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Fluid Passages
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
J 21867 Pressure Gauge
For equivalent regional tools, refer to Special Tools.
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 to verify correct fluid level and condition.
Note: Perform a scan tool snapshot, during the road test.
3. Perform the 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
Transmission ISS
Transmission OSS
Vehicle Speed
Shift Solenoid 1
TFP Switches
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. Verify the transmission line pressures are within the specified ranges.
If not within the specified ranges, refer to Fluid Pressure High or Low.
Ignition OFF, remove the Q8 control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission
Control Module Assembly Replacement.
Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test.
Test all solenoids on the Q8 control solenoid valve assembly. A pressure change should occur for each solenoid.
If the Q8 control solenoid valve assembly does not pass the performance test, replace the Q8 control
solenoid valve assembly.
Listed in the chart below are conditions for each component that could set DTC P0751 or P0752. Carefully
inspect each component for that condition. Repair or replace as necessary.
DTC Component Condition
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2/22/2021 DTC P0751 or P0752 • 2008 Cadillac CTS • MotoLogic
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DTC Component Condition
P0751
P0752 Lower Control Valve Body
Clutch select valve 2 stuck – debris, sediment, binding or
scored bore
P0751 Upper Control Valve Body
Bore Plug – Clutch Select Valve 2, Leaking, undersized
bore plug, or damaged
P0751 Upper Control Valve Body
Check Ball #2 missing, damaged, or leaking
Check Ball #2 Seat damaged or leaking
P0751
P0752 Q8 Control Solenoid Valve Assembly
Shift Solenoid (SS) 1:
O-ring seals leaking
Control signal fluid supply leak – valve body filter
plate assembly cracked or damaged gasket seal
Repair Instructions
Perform the Reset Transmission Adapts following all transmission related repairs.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Replace the control solenoid valve assembly. Refer to Control Module References for replacement, setup,
or programming.
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