For 1990-2009 cars

### 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
DTC P0872: Transmission Fluid Pressure (TFP) Switch 3 Circuit Low Voltage
DTC P0873: Transmission Fluid Pressure (TFP) Switch 3 Circuit High Voltage
DTC P0877: Transmission Fluid Pressure (TFP) Switch 4 Circuit Low Voltage
DTC P0878: Transmission Fluid Pressure (TFP) Switch 4 Circuit High Voltage
DTC P0989: Transmission Fluid Pressure (TFP) Switch 5 Circuit Low Voltage
DTC P0990: Transmission Fluid Pressure (TFP) Switch 5 Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | ---
TFP Switch 1 Signal | P0842 | P0843 | P0843
TFP Switch 3 Signal | P0872 | P0873 | P0873
TFP Switch 4 Signal | P0877 | P0878 | P0878
TFP Switch 5 Signal | P0989 | P0990 | P0990

### Typical Scan Tool Data

#### TFP Switches

Circuit | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine running, normal operating temperature Parameter Normal Range: 12 Volts = Hi, 0 Volts = Low
TFP Switch 1 | Low | Hi | Hi
TFP Switch 3 | Low | Hi | Hi
TFP Switch 4 | Low | Hi | Hi
TFP Switch 5 | Low | Hi | Hi

### Circuit/System Description

The transmission fluid pressure (TFP) switch assembly is part of the control solenoid (w/body and TCM) valve assembly and is not serviced separately. The transmission control module (TCM) supplies 12 volts to each TFP switch via its respective signal circuit. The TFP switch assembly has an internal case ground. Each TFP switch is normally closed, Low. When oil pressure is present at the TFP switch, the switch is Open, High. The TCM monitors each normally closed TFP switch signal circuit to determine clutch status.

### Conditions for Running the DTC

• | No TFT DTCs P0711, P0712, or P0713.

• | No pressure control solenoid electrical DTCs P0965, P0966, P0967, P0969, P0970, P0971, P2719, P2720, P2721, P2728, P2729, or P2730.

• | No shift solenoid electrical DTCs P0973, P0974, P0976, or P0977.

• | No IMS DTCs P1825 or P1915.

• | The engine speed is 1,100 RPM or greater.

• | Ignition voltage is between 9.0 volts and 19.0 volts.

• | The transmission fluid temperature (TFT) is 20-150°C (68-302°F).

### Conditions for Setting the 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 20 seconds or greater.

#### P0843

The TCM detects that the TFP switch 1 signal voltage is high, 12 volts when the 3-5-R clutch is commanded OFF for 20 seconds or greater.

#### P0872

The TCM detects that the TFP switch 3 signal voltage remains low, 0 volts when the 2-6 clutch is commanded ON for 20 seconds or greater.

#### P0873

The TCM detects that the TFP switch 3 signal voltage is high, 12 volts when the 2-6 clutch is commanded OFF for 20 seconds or greater.

#### P0877

The TCM detects that the TFP switch 4 signal voltage remains low, 0 volts when the 1-2-3-4 clutch is commanded ON for 20 seconds or greater.

#### P0878

The TCM detects that the TFP switch 4 signal voltage is high, 12 volts when the 1-2-3-4 clutch is commanded OFF for 20 seconds or greater.

#### P0989

The TCM detects that the TFP Switch 5 signal voltage remains low, 0 volts when the low and reverse/4-5-6 clutch is commanded ON for 20 seconds or greater.

#### P0990

the TCM detects that the TFP Switch 5 signal voltage is high, 12 volts when the low and reverse/4-5-6 clutch is commanded OFF for 20 seconds or greater.

### Action Taken When the DTC Sets

• | DTCs P0842, P0843, P0872, P0873, P0877, P0878, P0989, and P0990 are Type C DTCs.

• | The TCM freezes transmission adaptive functions.

### Conditions for Clearing the DTC

DTCs P0842, P0843, P0872, P0873, P0877, P0878, P0989, and P0990 are Type C DTCs.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Transmission General Description

• | Transmission Component and System Description

• | Electronic Component Description

• | Range Reference

• | Shift Solenoid Valve State and Gear Ratio

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. If there are any other transmission related DTCs set, diagnose those DTCs first. Refer to Diagnostic System Check - Vehicle.
2. Engine idling, parking brake applied, range selector in L (M), command the Shift Transmission with a scan tool to achieve 2nd gear.
3. Observe the suspect scan tool TFP Switch parameter while commanding the Shift Transmission with a scan tool to achieve 5th gear. Each TFP Switch parameter should toggle states (from High to Low or Low to High) between 2nd and 5th gear.

⇒ | If the specified parameter does not toggle, replace the control solenoid (w/body and TCM) valve assembly.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

| Note: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection.

• | Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming.

• | Perform the Service Fast Learn Adapts following all transmission related repairs.

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