DTC P0842 or P0843. Cadillac SLS 2009

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2009 🢒 SLS 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 DTC P0842 or P0843

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0842: Transmission Fluid Pressure (TFP) Switch 1 Circuit Low Voltage

DTC P0843: Transmission Fluid Pressure (TFP) Switch 1 Circuit High Voltage

The transmission fluid pressure (TFP) switch 1 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 1 on the TFP Switch 1 signal circuit; the TFP Switch 1 has an internal case ground. TFP Switch 1 is normally closed, Low. When oil pressure is present at the TFP Switch 1, the switch is Open, High. The normally high clutch pressure control (PC) solenoid 2 controls the transmission fluid to the 3-5-R clutch. The TCM monitors the normally closed TFP Switch 1 signal circuit to determine the 3-5-R clutch status.

Conditions for Running the DTC

•	DTCs P0711, P0712 or P0713 are not set.

•	No DTCs P0965, P0966, P0967, P0968, P0969, P0970, or P0971.

•	No DTCs P0973, P0974, P0976, P0977, P2719, P2720, P2728, P2729, or P2730.

•	No DTC P1825 or P1915.

•	DTC P2721 is not set.

•	The Transmission Fluid Temperature (TFT) is between 20 and 150°C (68 and 302°F).

•	The engine speed is greater than or equal to 1,100 RPM.

Conditions for Setting the DTC

P0842

•	Without Start Test

•	Regular Test

-	The TCM does not turn off during the process.

-	The PC solenoid valve 2 hydraulic is 100 kPa or less for 0.45 second.

-	The pressure switch remain closed for 5.5 seconds.

P0843

•	Without Start Test

•	Regular Test

-	The TCM does not turn off during the process.

-	Engine running.

-	The PC solenoid valve 2 hydraulic is 600 kPa or greater for 1 second.

-	Keep the pressure switch OFF for 5.5 seconds.

Action Taken When the DTC Sets

•	DTCs P0842 and P0843 are Type C DTCs.

•	The TCM freezes transmission adaptive functions.

Conditions for Clearing the DTC

DTCs P0842 and P0843 are Type C DTCs.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

DTC Type Reference

•	Diagnostic Trouble Code (DTC) Type Definitions

•	Diagnostic Trouble Code (DTC) List/Type

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Circuit/System Verification

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

Circuit/System Testing

Ensure the TFT is near the temperature displayed in the Failure Records.
Start the engine and observe the TFP Switch 1 parameter while moving the range selector lever from Park to Reverse. The TFP Switch 1 should transition from Hi in Park to Low in Reverse.

⇒	If the TFP Switch 1 parameter does not change, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection.

⇒	If no concerns are found, replace the control solenoid valve and TCM assembly.

Component Testing

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Service Fast Learn Adapts

•	Control Module References for TCM replacement, setup, and programming