P0878
DTC P0877 or P0878
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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 has no seviceable parts. 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
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.
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.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Description and Operation
Electronic Component Description (Electronic Component Description)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
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 (Verification Tests) after completing the diagnostic procedure.
* Control solenoid (w/body and TCM) valve assembly replacement. Refer to Control Module References (Programming and Relearning) for replacement, setup, and programming.
* Perform the Service Fast Learn Adapts (Programming and Relearning) if internal transmission repairs are performed.