P0873
DTC P0872 or P0873
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0872
-
Transmission Fluid Pressure (TFP) Switch 3 Circuit Low Voltage
DTC P0873
-
Transmission Fluid Pressure (TFP) Switch 3 Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The transmission fluid pressure (TFP) switch 3 is part of the control solenoid valve assembly, which has no serviceable components. The transmission control module (TCM) supplies a signal circuit to the TFP switch 3. The TFP switch 3 has an internal case ground. The TFP switch 3 is normally closed or LOW. When oil pressure is present at the TFP switch 3, the switch is open or HIGH. The normally low clutch pressure control (PC) solenoid 4 controls pressure to the 2-6 clutch regulator valve. The TCM monitors the TFP switch 3 to determine the position of the 2-6 clutch regulator valve. When the 2-6 clutch is commanded OFF, pressure is present on the TFP switch 3. When the 2-6 clutch is commanded ON, the 2-6 clutch regulator valve moves and pressure to the TFP switch 3 is exhausted through the 2-6 clutch regulator valve.
Conditions for Running the DTC
P0872 or P0873
* DTC P0711, P0712, P0713, P0716, P0717, P0722, P0723, P0742, P0751, P0756, P0757, P0973, P0974, P0976, P0977, P1915, or P182E is not set.
* High side driver is enabled.
* Engine speed is 400 RPM or greater for 5 seconds.
* Engine speed is 550 RPM or greater.
* Ignition voltage is 8.6 volts or greater.
* Transmission fluid temperature (TFT) is 0 to +120°C (32-248°F).
Conditions for Setting the DTC
P0872
The TCM detects that the TFP switch 3 signal voltage remains LOW after the 2-6 clutch transitions from a HIGH pressure state to a LOW pressure state. The TCM counts each incident. The DTC sets when 18 counts are accumulated.
P0873
The TCM detects that the TFP switch 3 signal voltage remains HIGH after the 2-6 clutch transitions from a LOW pressure state to a HIGH pressure state. The TCM counts each incident. The DTC sets when 20 counts are accumulated.
Action Taken When the DTC Sets
* DTCs P0872 and P0873 are Type C DTCs.
* TCM freezes transmission adaptive functions for the 2-6 clutch.
Conditions for Clearing the DTC
DTCs P0872 and P0873 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 Electrical Diagrams
Connector End View Reference
* Component Connector End Views A/C Compressor Clutch
* Inline Harness Connector End Views X101
Description and Operation
* Transmission General Description Transmission General Description
* Electronic Component Description Electronic Component Description for control solenoid valve assembly
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
DT-47825-20 - Adapter Harness
For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
Warning:
Refer to Parking Brake and Drive Wheels Warning Parking Brake and Drive Wheels Warning in the preface section.
1. Engine idling in Park with parking brake applied, and drive wheels chocked.
2. Verify with a scan tool the TFP 1, TFP Switch 3, TFP Switch 4, and TFP Switch 5 parameter states are correct for the Park, Reverse, and Neutral gear select lever positions. Refer to Transmission Fluid Pressure Switch Logic Transmission Fluid Pressure Switch Logic.
• If any parameter value is not correct for a given gear range
Refer to Circuit/System Testing below.
• If parameter values are correct for all gear ranges
3. Verify the TFP Switch 1, TFP Switch 3, TFP Switch 4, and TFP Switch 5 parameter states are correct for each forward range with the gear select lever in Drive, using the scan tool to command all forward ranges. Refer to Transmission Fluid Pressure Switch Logic Transmission Fluid Pressure Switch Logic.
• If any parameter value is not correct for a given gear range
Refer to Circuit/System Testing below.
• If parameter values are correct for all gear ranges
4. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.
Circuit/System Testing
Note:
You must perform the Circuit/System Verification first.
1. Ignition OFF. Remove the Q8 control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement Service and Repair.
2. Place the Q8 control solenoid valve assembly on a clean work surface near the transmission assembly.
3. Connect the DT-47825-20 - harness between the vehicle wire harness X1 20-way transmission electrical connector, and the Q8 control solenoid valve assembly electrical connector.
4. Ignition ON, verify with a scan tool that the TFP Switch 1, TFP Switch 3, TFP Switch 4, and TFP Switch 5 parameters change states when gently pushing on each TFP switch with the eraser end of a pencil.
• If any TFP Switch parameter does not change states
Replace the Q8 control solenoid valve assembly.
• If all TFP Switch parameters change states
5. Inspect the channel plate, spacer plate, and filter plate for debris and blocked orifices.
Repair Instructions
Note:
* Perform the Reset Transmission Adapts Reset Transmission Adapts following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection.
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Control Module References Control Module References for control solenoid valve assembly replacement, setup, or programming