Circuit Description
The Transmission Control Module (TCM) monitors the following conditions:
| • | The throttle opening |
| • | The engine speed |
| • | The vehicle speed |
| • | The gear position |
The TCM compares the actual engine speed to the TCM specified value. The TCM specified value is the engine speed the TCM obtains through calculation by using the above conditions.
Conditions for Setting the DTC
| • | When the engine runs in DRIVE range, the gear change control from the TCM to the transmission does not agree with the actual gear position. The above condition exists even though solenoid valve #2 is electrically in good condition. The engine speed and the vehicle speed determine the gear position. |
| • | Two driving cycle detection logic |
Action Taken When the DTC Sets
| • | DTC P0756 stores. |
| • | The Malfunction Indicator Lamp (MIL) turns ON. |
Diagnostic Aids
Inspect for the following conditions:
| • | The shift solenoid valve #2 is stuck. |
| • | The 1-2 shift valve is stuck. |
| • | The 3-4 shift valve is stuck. |
| • | The valve body fluid passage is clogged. |
| • | A 2nd brake malfunction exists. |
| • | A faulty TCM exists. |
If DTC P0756 cannot duplicate, the information included in the Freeze Frame data may be useful in determining the vehicle operating conditions when the DTC set.
DTC Confirmation Procedure
- Turn the ignition switch to the LOCK position.
- Connect the scan tool to the Data Link Connector (DLC).
- Turn the ignition switch ON.
- Use the scan tool in order to clear the following items:
- Start the engine.
- Warm the engine up to normal operating conditions.
- Accelerate the vehicle in DRIVE range.
- Stop the vehicle.
- Use the scan tool in order to test for a pending DTC.
| • | DTC P0756 |
| • | Any pending DTCs |
Inspect for upshifting in the following gears as the vehicle speed increases:
| 7.1. | 1st gear |
| 7.2. | 2nd gear |
| 7.3. | 3rd gear |
| 7.4. | 4th gear |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. The scan tool creates an electronic copy of the data taken when the fault occurred. The information then stores in the scan tool for later reference.
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This step tests for proper shift points.
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This step inspects for a leaky solenoid #2.
Refer to the above figure.
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This step inspects for a stuck closed TCC solenoid #2.
Refer to the above figure.
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This step inspects the condition of the valve body assembly.
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This step inspects for a faulty TCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the On-Board Diagnostic (OBD) System Check performed? | -- | |||
2 | Use J 39200 in order to test for DTC(s). Does the scan tool display any other DTC(s) in addition to DTC P0756? | -- | Go to the applicable DTC table. | |
Perform the Upshifts and Torque Converter Clutch (TCC) Apply procedure. Refer to Road Test . This procedure diagnoses the mechanical condition of the transmission and the torque converter. Repair if necessary. Is the procedure complete? | -- | -- | ||
4 | Perform the DTC Confirmation Procedure. Did DTC P0756 reset? | -- | ||
Did the shift solenoid #2 outlet port remain closed with no air leakage? | -- | |||
Did the shift solenoid #2 outlet port open and enable air to escape? | -- | |||
7 | Refer to DTC P0705 Trans Range Switch Circuit for diagnosis of the transmission range switch. Is the action complete? | -- | -- | |
8 | Refer to DTC P0720 Output Speed Sensor Circuit for the diagnosis of the Vehicle Speed Sensor (VSS). Is the action complete? | -- | -- | |
Is the valve body in good condition? | -- | |||
Does DTC P0756 reset? | -- | |||
11 | Repair or overhaul the valve body assembly. Refer to Valve Body and Accumulator Pistons Removal . Is the repair complete? | -- | -- | |
12 | The Malfunction is not present at this time. Refer to Diagnostic Aids. Is the action complete? | -- | System OK | -- |
13 | Replace the shift solenoid assembly. Refer to Shift Solenoid Replacement . Is the procedure complete? | -- | -- | |
14 | Diagnose the mechanical condition of the transmission. Refer to Hydraulic/Mechanical Diagnosis for additional diagnostics. Is the action complete? | -- | -- | |
15 | Replace the TCM. Is the procedure complete? | -- | -- | |
16 | Perform the DTC Confirmation Procedure. Does the scan tool display any DTC(s)? | -- | Go to the applicable DTC table | System OK |
