2010 Cadillac Truck SRX FWD V6-3.0L Page 1789

2010 Cadillac Truck SRX FWD V6-3.0L Page 1789

DTC P0878

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

Diagnostic Fault Information

Circuit/System Description

The transmission fluid pressure (TFP) switch 4 is part of the control solenoid valve assembly which has no serviceable parts. The TCM supplies a

signal circuit to the TFP switch 4. The TFP switch 4 has an internal case ground. TFP switch 4 is normally closed or LOW. When oil pressure is

present at the TFP switch 4, the switch is open or HIGH. The normally LOW pressure control solenoid 5 controls pressure to the 1-2-3-4 clutch

regulator valve. The TCM monitors the TFP switch 4 to determine the position of the 1-2-3-4 clutch regulator valve. When the 1-2-3-4 clutch is

commanded OFF, pressure is present on the TFP switch 4. When the 1-2-3-4 clutch is commanded ON, the 1-2-3-4 clutch regulator valve moves

and pressure to the TFP switch 4 is exhausted through the 1-2-3-4 clutch regulator valve.

Conditions for Running the DTC

P0877 or P0878

* No DTCs P0711, P0712, P0713, P0716, P0717, P0722, P0723, P0742, P0751, P0756, P0757, P0973, P0974, P0976, P0977, P1915, P182E.

* The engine speed is 400 RPM or greater for 5 seconds.

* The engine speed is 550 RPM or greater.

* Ignition voltage is 8.6 volts or greater.

* The transmission fluid temperature (TFT) is 0-120掳C (32-248掳F).

Conditions for Setting the DTC

P0877

The TCM detects that the TFP switch 4 signal voltage remains LOW after the 1-2-3-4 clutch transitions from a HIGH pressure state to a LOW

pressure state. The TCM counts each incident. The DTC sets when 5 counts are accumulated.

P0878

The TCM detects that the TFP switch 4 signal voltage remains HIGH after the 1-2-3-4 clutch transitions from a LOW pressure state to a HIGH

pressure state. The TCM counts each incident. The DTC sets when 8 counts are accumulated.

Action Taken When the DTC Sets

* DTCs P0877 and P0878 are Type C DTCs.

* The TCM freezes transmission adaptive functions for the 1-2-3-4 clutch.

Conditions for Clearing the DTC

DTCs P0877 and P0878 are Type C DTCs.

Diagnostic Aids

A TFP switch may malfunction due to normal debris in the transmission fluid causing a TFP Switch DTC to intermittently set. This type of failure

should not be immediately noticeable to a customer, as the switch outputs are used for shift adaptives and do not cause transmission symptoms

unless the switch malfunctions continuously for an extended period of time.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics (See: Transmission and Drivetrain/Automatic Transmission/Transaxle/Diagrams)

Connector End View Reference

* Component Connector End Views (See: Diagrams/Connector Views/Connector End Views By Name)

* Inline Harness Connector End Views (See: Diagrams/Connector Views/Multiple Junction Connector/Connector End Views By Number)

Description and Operation