The Powertrain Control Module (PCM) uses signals from the Vehicle Speed Sensor (VSS) and the Crankshaft Position (CKP) sensor to detect the actual gear position. The PCM then compares the actual gear with the shift schedule in the PCM memory to detect mechanical trouble of the shift solenoid #1.
DTC P0751 will set when the following conditions are met:
• | The gear required by the PCM does not match the actual gear. |
• | Two driving cycle detection logic. |
A DTC P0751 is stored and the Malfunction Indicator Lamp (MIL) is turned ON.
Inspect for the following conditions:
• | Shift select cable out of adjustment. |
• | Clogged or leaky shift solenoid #1. |
• | Transaxle mechanical malfunction. |
• | Valve body fluid passage clogged. |
• | A faulty PCM |
An intermittent may be caused by the following conditions:
• | A poor connection |
• | Rubbed through wire insulation |
• | A broken wire inside the insulation |
Perform the following steps if DTC P0751 cannot be duplicated:
• | The DTC |
• | The pending DTC |
• | Freeze frame data |
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. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
This step checks for proper shift points.
This step checks for a leaky shift solenoid #1.
This step checks for a stuck closed shift solenoid #1.
This step checks the condition of the valve body assembly.
This step checks for a faulty PCM.
Step | Action | Yes | No |
---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | |||
Was the On-Board Diagnostic (OBD) System Check performed? | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls | |
2 |
Does the scan tool display any other DTCs in addition to DTC P0751? | Go to applicable DTC table | Go to Step 3 |
Perform the Upshifts and Torque Converter Clutch Apply Procedure in Road Test in order to diagnose mechanical condition of transaxle. Is the action complete? | Go to Step 4 | -- | |
4 | Perform the DTC Confirmation Procedure. Did this DTC reset? | Go to Step 5 | Go to Step 11 |
Did shift solenoid #1 outlet port open and air escape? | Go to Step 12 | Go to Step 6 | |
Did shift solenoid #1 outlet port open and air escape? | Go to Step 7 | Go to Step 12 | |
7 | Refer to DTC P1780 for diagnosis of PNP switch. Is the action complete? | Go to Step 8 | -- |
Remove valve body and inspect the passages for any obstructions/restrictions. Refer to Solenoids and Wiring Harness Replacement. Is the valve body in good condition? | Go to Step 9 | Go to Step 10 | |
Does this DTC reset? | Go to Step 13 | Go to Step 14 | |
10 | Repair or overhaul the valve body assembly. Refer to Solenoids and Wiring Harness Replacement. Is the action complete? | Go to Step 15 | Go to Step 14 |
11 | A malfunction is not present at this time. Refer to Diagnostic Aids. Is action complete? | System OK | -- |
12 | Replace shift solenoid #1. Is action complete? | Go to Step 15 | -- |
13 | Refer to Line Pressure Check for further diagnosis of the transaxle's performance. Repair as necessary. Is the action complete? | Go to Step 15 | -- |
14 | Replace Powertrain Control Module (PCM). Refer to Powertrain Control Module Replacement in Engine Controls. Is action complete? | Go to Step 15 | -- |
15 | Perform the DTC Confirmation Procedure. Are any DTCs displayed on the Scan Tool? | Go to applicable DTC table | System OK |