2010 Cadillac Truck SRX FWD V6-3.0L Page 1769
- Transmission Fluid Pressure (TFP) Switch 1 Circuit Low Voltage
DTC P0843
- Transmission Fluid Pressure (TFP) Switch 1 Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The transmission fluid pressure (TFP) switch 1 is part of the control solenoid valve assembly, which has no serviceable parts. The TCM supplies a
signal circuit to the TFP Switch 1. The TFP Switch 1 has an internal case ground. TFP Switch 1 is normally closed or LOW. When oil pressure is
present at the TFP Switch 1, the switch is open or HIGH. The normally high clutch pressure control (PC) solenoid 2 controls pressure to the 3-5
reverse clutch regulator valve. The TCM monitors the TFP switch 1 to determine the position of the 3-5 reverse clutch regulator valve. When the
3-5 reverse clutch is commanded OFF, pressure is present on the TFP switch 1. When the 3-5 reverse clutch is commanded ON, the 3-5 reverse
clutch regulator valve moves and pressure to the TFP switch 1 is exhausted through the 3-5 reverse clutch regulator valve.
Conditions for Running the DTC
P0842 or P0843
* No DTCs P0711, P0712, P0713, P0716, P0717, P0722, P0723, P0742, P0751, P0756, P0757, P0973, P0974, P0976, P0977, P1915, P182E.
* The high side driver is on.
* 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
P0842
The TCM detects that the TFP switch 1 signal voltage remains LOW after the 3-5-R clutch transitions from a HIGH pressure state to a LOW
pressure state. The TCM counts each incident. The DTC sets when 25 counts are accumulated.
P0843
The TCM detects that the TFP switch 1 signal voltage remains HIGH after the 3-5-R clutch transitions from a LOW pressure state to a HIGH
pressure state. The TCM counts each incident. The DTC sets when 35 counts are accumulated.
Action Taken When the DTC Sets
* DTCs P0842 and P0843 are Type C DTCs.
* The TCM freezes transmission adaptive functions for the 35R clutch.
Conditions for Clearing the DTC
DTCs P0842 and P0843 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)
