P0878

DTC P0877 or P0878

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors
DTC P0877
- Transmission Fluid Pressure (TFP) Switch 4 Circuit Low Voltage

DTC P0878
- Transmission Fluid Pressure (TFP) Switch 4 Circuit High Voltage

Diagnostic Fault Information





Typical Scan Tool Data





Circuit/System Description

The transmission fluid pressure (TFP) switch 4 is part of the control solenoid (w/body and TCM) valve assembly and is not serviced separately. The TCM supplies 12 volts to the TFP switch 4 on the TFP switch 4 signal circuit; the TFP switch 4 has an internal case ground. TFP switch 4 is normally closed, Low. When oil pressure is present at the TFP switch 4, the switch is open, high. The normally low clutch pressure control (PC) solenoid 4 controls the transmission fluid to the 1-2-3-4 clutch. The TCM monitors the normally closed TFP switch 4 signal circuit to determine the 1-2-3-4 clutch status.

Conditions for Running the DTC

* No DTCs P0120, P0711, P0712, or P0713.
* No DTCs P0965, P0966, P0967, P0968, P0969, P0970, or P0971.
* No DTCs P0973, P0974, P0976, P0977, P2719, P2720, P2728, P2729, or P2730.
* No DTCs P1825 or P1915.
* Ignition voltage is between 11-15 volts.
* The transmission fluid temperature (TFT) is 20-150°C (68-302°F).

Conditions for Setting the DTC

DTC P0877

The TCM detects that the TFP switch 4 signal voltage remains low, 0 volts when the 1-2-3-4 clutch is commanded ON for 5 seconds.

DTC P0878

The TCM detects that the TFP switch 4 signal voltage is high, 12 volts when the 1-2-3-4 clutch is commanded OFF.

Action Taken When the DTC Sets

* DTCs P0877 and P0878 are Type C DTCs.
* The TCM freezes transmission adaptive functions.

Conditions for Clearing the DTC

DTCs P0877 and P0878 are Type C DTCs.

Circuit/System Verification

If there are any other transmission related DTCs set, diagnose those DTCs first.

Circuit/System Testing

1. Ensure the TFT is near the temperature displayed in the Failure Records.
2. Start the engine and place the transmission range selector in D6.
3. Observe the TFP switch 4 parameter while commanding 4th gear and then commanding 5th gear with the scan tool. The TFP Switch 4 should transition from High in 4th gear to Low in 5th gear.

- If the TFP switch 4 parameter state does not change, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection. Control Solenoid Valve and Transmission Control Module Assembly Inspection
- If no concerns are found, replace the control solenoid (w/body and TCM) valve assembly.

Component Testing

Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection. Control Solenoid Valve and Transmission Control Module Assembly Inspection

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

1. control solenoid (w/body and TCM) valve assembly replacement. Refer to Control Module References for replacement, setup, and programming.
2. Perform the Service Fast Learn Adapts. Programming and Relearning