DTC P0756
DTC P0756 |
Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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DTC Descriptor |
DTC P0756
Shift Solenoid Valve 2 Performance - Stuck Off
Circuit/System Description |
The shift solenoid (SS) valve 2 is part of the control solenoid valve assembly, which has no serviceable components. The SS valve 2 is a normally closed (NC) solenoid valve and controls fluid to the clutch select valve 3. The solenoid operates by the transmission control module (TCM) opening or closing the ground circuit. With the solenoid circuit grounded, solenoid on, the internal plunger moves and allows the metering ball to move away from the feed seat and against the exhaust seat, creating signal fluid pressure. The signal fluid acts against the clutch select valve 3 to overcome the valve spring force, moving it to the apply position.
Conditions for Running the DTC |
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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.
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The engine speed is 400 RPM or greater for 5.0 seconds.
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The high side driver is enabled.
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The ignition voltage is 8.6 volts or greater.
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The throttle position signal is valid.
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The transmission fluid temperature (TFT) is -7°C (19°F) or greater.
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Conditions for Setting the DTC |
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Commanded Gear is 1st locked.
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Gearbox Slip is 400 RPM or greater for 3.0 seconds.
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If above conditions exist, the TCM will command second range. If the gear ratio is between 2.7 and 3.0 for 1.0 second, the counter will increment. The DTC will set after 3 occurrences.
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Action Taken When the DTC Sets |
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DTC P0756 is a Type A DTC.
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The TCM inhibits Tap Up/Down function.
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The TCM inhibits manual shifting of forward gears.
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The TCM commands maximum line pressure.
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The TCM freezes transmission adaptive functions.
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The TCM limits the transmission to Reverse, 1st, and 3rd gear operation.
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Conditions for Clearing the DTC |
DTC P0756 is a Type A DTC.
Reference Information |
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
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Component Connector End Views
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Inline Harness Connector End Views
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Description and Operation
Transmission General Description
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification |
1. |
Perform the Transmission Fluid Level and Condition Check to verify correct fluid level and condition. |
2. |
Perform the road test . Verify the transmission operation performs as indicated, in the road test instructions. |
3. |
Review the scan tool snapshot transmission data parameters. Verify the engine and transmission data parameters display the correct values in all forward gear ranges:
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Engine Speed
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Transmission ISS
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Transmission OSS
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Vehicle Speed
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Shift Solenoid Valve 2
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Transmission Fluid Pressure Switch 1
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Transmission Fluid Pressure Switch 3
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Transmission Fluid Pressure Switch 4
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Transmission Fluid Pressure Switch 5
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4. |
Register freeze frame/failure record data. Delete the diagnostic trouble codes.
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5. |
Engine running, brakes applied, transmission gear shift selector in Reverse. Shift to Drive and accelerate to 56 km/h (35 mph) with calculated throttle position greater than 15 percent. Perform this test 5 consecutive times. The DTC should not set.
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6. |
After you complete the steps described above, check the diagnostic trouble code is not reset by driving the vehicle according to the conditions for running diagnostic trouble codes (DTC). You can also drive the vehicle according to the conditions you see in Freeze Frame/ Failure records. If the vehicle passes the circuit/system verification procedure, then stop. Do not perform the circuit/system test or component test as this may result in unnecessary part replacement. Refer to
Testing for Intermittent Conditions and Poor Connections
.
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Circuit/System Testing |
1. |
Perform the
line pressure check
. Check that the transmission's line pressure is within the range specified in the table Line PC-solenoid valve pressure. Refer to
Solenoid Valve Pressure
.
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2. |
If not within the specified ranges, refer to
Fluid Pressure High or Low
.
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3. |
Remove control solenoid valve assembly Q8 with ignition OFF. See
Replacing control solenoid valve assembly and transmission control module
.
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4. |
Perform the
Test of the control solenoid valve assembly and the transmission control module's solenoid performance
. Test all solenoid valves on the Q8 control solenoid valve assembly. A pressure change should occur for each solenoid.
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5. |
If the Q8 control solenoid valve assembly does not pass the performance test, replace the Q8 control solenoid valve assembly.
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6. |
Listed in the table below are conditions for each component that could set DTC P0756. Carefully inspect each component for that condition. Repair or replace as necessary.
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DTCs | Component | Condition | |||||||||
P0756 | Upper Control Valve Body |
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P0756 | Q8 Control Solenoid Valve Assembly |
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P0756 | Pump Assembly | Fluid pump vanes and fluid pump rotor broken | |||||||||
P0756 | Pump Seal | Seal is torn or cut, causing a small leak that is overcome with enough speed and pump capacity. | |||||||||
P0756 | Mechanical Diode | Broken or not capable of holding torque |
Repair Instructions |
Note | ||
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Perform the
Resetting of the transmission's adaption
after all transmission repairs.
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Before replacing the TCM, perform the
Control Solenoid Valve and Transmission Control Module Assembly Inspection
.
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Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Control Valve Upper Body Assembly Cleaning and Inspection
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Control Module References
for control solenoid valve assembly replacement, setup, or programming
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