2010 Cadillac CTS Sedan AWD V6-3.6L Page 1719
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/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 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 is exhausted through the 1-2-3-4 clutch regulator valve.
Conditions for Running the DTC
P0877 or P0878
* DTCs P0711, P0712, P0713, P0973, P0974, P0976, P0977, P1915, or P182E are not set.
* Ignition voltage is 8.6 volts or greater.
* The transmission fluid temperature (TFT) is 0-120掳C (32-248掳F).
* Engine speed is 500 RPM or greater for 5 seconds.
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 20 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 18 counts are accumulated.
Action Taken When the DTC Sets
* DTCs P0877 and P0878 are Type C DTCs.
* The TCM freezes transmission adaptive functions.
