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 Descriptors
DTC P0751: Shift Solenoid (SS) 1 Valve Performance - Stuck OffDTC P0756: Shift Solenoid (SS) 2 Valve Performance - Stuck Off
DTC P0761: Shift Solenoid (SS) 3 Valve Performance - Stuck Off
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
PS1 Signal | P0752, P0842 | P0751, P0843 | -- | -- |
PS2 Signal | P0757, P0847 | P0756, P0848 | -- | -- |
PS3 Signal | P0762, P0872 | P0761, P0873 | -- | -- |
Typical Scan Tool Data
Display Parameters | Normal Range | Short to Ground | Open/High Resistance | Short to Voltage |
|---|---|---|---|---|
Operating Conditions: Ignition ON, engine OFF | ||||
TFP Switch 1 | High | Low | High | -- |
TFP Switch 2 | High | Low | High | -- |
TFP Switch 3 | High | Low | High | -- |
Operating Conditions: Engine running, transmission in park or neutral position | ||||
TFP Switch 1 | Low | Low | High | -- |
TFP Switch 2 | Low | Low | High | -- |
TFP Switch 3 | Low | Low | High | -- |
Circuit/System Description
The pressure switch manifold (PSM) is a multiple switch assembly made up of 3 normally open (N/O) pressure switches and 1 normally closed (N/C) pressure switch. Pressure switch 1 (PS1) monitors shift valve 1 positioning, pressure switch 2 (PS2) monitors shift valve 2 positioning and pressure switch 3 (PS3) monitors shift valve 3 positioning. The pressure switches communicate the positioning to the transmission control module (TCM). The position of the shift valves 1, 2, and 3 is controlled by 3 normally closed shift solenoids 1, 2, and 3 (SS1, SS2, and SS3). When energized, the shift solenoids direct control main pressure to shift valve 1, 2, or 3, which strokes the shift valve.
Conditions for Running the DTC
P0751
| • | Engine Running. |
| • | Shift solenoid 1 (SS1) is commanded ON. |
P0756
| • | Engine Running. |
| • | Shift solenoid 2 (SS2) is commanded ON. |
P0761
| • | Engine Running. |
| • | Shift solenoid 3 (SS3) is commanded ON. |
Conditions for Setting the DTC
P0751
| • | Engine Running. |
| • | SS1 is commanded ON and PS1 remains OFF for up to 12 seconds depending on transmission fluid temperature. |
P0756
| • | Engine Running. |
| • | SS2 is commanded ON and PS2 remains OFF for up to 12 seconds depending on transmission fluid temperature. |
P0761
| • | Engine Running. |
| • | SS3 is commanded ON and PS3 remains OFF for up to 12 seconds depending on transmission fluid temperature. |
Action Taken When the DTC Sets
P0751
| • | The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL). |
| • | When in a forward range, the transmission will shift to another forward range, unless the transmission is compromised by overspeeding. |
| • | When the shift selector is moved from a forward range to NEUTRAL or from a forward range to REVERSE, then the transmission will shift to NEUTRAL. |
| • | If the shift selector is moved to forward, the transmission will shift to forward and if the selector is moved to REVERSE, the transmission will shift to REVERSE, unless the transmission is compromised by overspeeding or direction change, then a shift to NEUTRAL is made. |
| • | DTC P0751 is stored in TCM history. |
| • | The TCM freezes shift adapts. |
| • | The TCM inhibits torque converter clutch (TCC) engagement. |
P0756
| • | The TCM requests the ECM to illuminate the MIL. |
| • | When in a forward range and shifting is completed, the transmission will shift to another forward range, unless the transmission is compromised by overspeeding or direction change, then the transmission will shift to NEUTRAL. |
| • | If the shift selector is moved to forward, the transmission will shift to forward and if the selector is moved to REVERSE, the transmission will shift to REVERSE, unless the transmission is compromised by overspeeding or direction change, then a shift to NEUTRAL is made. |
| • | DTC P0756 is stored in TCM history. |
| • | The TCM freezes shift adapts. |
| • | The TCM inhibits TCC engagement. |
P0761
| • | The TCM requests the ECM to illuminate the MIL. |
| • | When in a forward range and shifting is completed, the transmission will shift to another forward range, unless the transmission is compromised by overspeeding or direction change, then the transmission will shift to NEUTRAL. |
| • | If the shift selector is moved to forward, the transmission will shift to forward and if the selector is moved to REVERSE, the transmission will shift to REVERSE, unless the transmission is compromised by overspeeding or direction change, then a shift to NEUTRAL is made. |
| • | DTC P0761 is stored in TCM history. |
| • | The TCM freezes shift adapts. |
| • | The TCM inhibits TCC engagement. |
Conditions for Clearing the DTC
DTCs P0751, P0756, and P0761 are Type A DTCs.
Diagnostic Aids
| • | If DTC P0701 is set in combination with either DTC P0751, P0756 or P0761, diagnose P0701 prior to proceeding to DTCs P0751, P0756 or P0761. |
| • | You may have to drive the vehicle in order to experience a condition. |
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Engine running, command the transmission through the forward ranges with a scan tool. Compare the TFP Switch 1, TFP Switch 2, and TFP Switch 3 parameters in each forward range with the PSM Logic table. Refer to Pressure Switch Manifold (PSM) Logic.
- Operate the vehicle within the Conditions 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
- Inspect the transmission fluid level. Refer to Transmission Fluid Check.
- Ignition OFF, disconnect the X175 harness connector at the transmission.
- Ignition ON, engine OFF, connect a 3A fused jumper wire to the PS1 signal circuit terminal D to ground, PS2 signal circuit terminal F to ground, and PS3 signal circuit terminal E to ground. Verify with a scan tool the TFP Switch 1, TFP Switch 2, and TFP Switch 3 parameters changes from High to Low when the signal circuit is grounded.
- Ignition OFF, connect the X175 harness connector to the transmission.
- Remove the pressure switch module from the valve body. Leave the internal wire harness connected to the pressure switch manifold. Refer to Pressure Switch Manifold Replacement.
- Connect a jumper wire to the base of the pressure switch module and ground.
- Ignition ON, engine OFF, gently push on the PS1, PS2, and PS3 switches. Verify with a scan tool that TFP Switch 1, TFP Switch 2, and TFP Switch 3 parameters changed from High to Low.
- If all circuits test normal, refer to Control Valve Body Assembly Disassemble and Control Valve Body Cleaning and Inspection.
| ⇒ | If not the specified value, test the affected pressure switch signal circuit for an open/high resistance. If circuits tests normal, replace the TCM. |
| ⇒ | If not the specified value, test the internal wire harness circuits for an open/high resistance. If the circuits test normal, replace the pressure switch module. |
| ⇒ | If valve body inspection is normal, replace the shift solenoid indicated by the DTC, refer to Control Valve Solenoid Replacement. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for TCM replacement, setup, and programming |
Repair Verification
If another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.
