Circuit Description
The powertrain control module (PCM) monitors the following conditions:
| • | The throttle opening |
| • | The engine speed |
| • | The vehicle speed |
| • | The gear position |
The PCM compares the actual engine speed to the PCM specified value. The PCM specified value is the engine speed the PCM obtains through calculation by using the above conditions.
Conditions for Setting the DTC
| • | When running the engine in DRIVE range, gear change control from the PCM to the transmission does not agree with the actual gear position. The above condition occurs even though solenoid valve #1 is electrically in good condition. Engine speed and the vehicle speed sensor signal determine gear position. |
| • | Two driving cycle detection logic |
Action Taken When the DTC Sets
| • | DTC P0751 stores. |
| • | The malfunction indicator lamp (MIL) turns ON. |
Diagnostic Aids
Inspect for the following conditions:
| • | The shift solenoid valve #1 is stuck. |
| • | The 2-3 shift valve is stuck. |
| • | The valve body fluid passage is clogged. |
| • | A direct clutch malfunction exists. |
| • | A faulty PCM exists. |
If DTC P0751 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 P0751 |
| • | 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.
-
The Powertrain 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.
-
This step tests for proper shift points.
-
This step inspects for a leaky solenoid #1.
Refer to the above figure.
-
This step inspects for a stuck closed TCC solenoid #1.
Refer to the above figure.
-
This step inspects the condition of the valve body assembly.
-
This step inspects for a faulty PCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the On-Board Diagnostic (OBD) System Check performed? | -- | |||
2 |
Does the scan tool display any other DTCs in addition to DTC P0751? | -- | Go to the applicable DTC table | |
Perform the Upshifts and Torque Converter Clutch (TCC) Apply procedure. Refer to Road Test . Is the procedure complete? | -- | -- | ||
4 |
Did the shift solenoid #1 outlet port remain closed with no air leakage? | -- | ||
Did the shift solenoid #1 outlet port open and enable air to escape? | -- | Go to Diagnostic Aids | ||
6 |
Refer to Valve Body and Accumulator Pistons Removal . Is the valve body in good condition? | -- | ||
7 |
Does DTC P0751 reset? | -- | ||
8 | Repair or overhaul the valve body assembly. Refer to Valve Body and Accumulator Pistons Removal . Is the repair complete? | -- | -- | |
9 | Replace the shift solenoid assembly. Refer to Shift Solenoid Replacement . Is the procedure complete? | -- | -- | |
10 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the procedure complete? | -- | -- | |
11 | Diagnose the mechanical condition of the transmission. Is the action complete? | -- | -- | |
12 | Perform the DTC Confirmation Procedure. Does the scan tool display any DTC(s)? | -- | Go to the applicable DTC table | System OK |
