P0843

DTC P0842 or P0843

DTC Descriptors

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

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

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview





Typical Scan Tool Data





Circuit/System Description

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

* 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

DTC P0842

The TCM detects that the TFP switch 1 signal voltage remains low, 0 volts when the 3-5-R clutch is commanded ON for 5 seconds.

DTC P0843

The TCM detects that the TFP switch 1 signal voltage is high, 12 volts when the 3-5-R clutch is commanded OFF.

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

* Automatic Transmission Inline 16-Way Connector End View
* Automatic Transmission Internal Connector End Views
* Automatic Transmission Related 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 in Diagnostic Aids
* Wiring Repairs

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 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. 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. Control Solenoid Valve and Transmission Control Module Assembly Inspection

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

1. control solenoid (w/body and TCM) valve assembly replacement.
2. Perform the Service Fast Learn Adapts. Programming and Relearning