Service Information

Orlando

DTC P0872 or P0873

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 P0872: Transmission Fluid Pressure Switch 3 Circuit Low Voltage

DTC P0873: Transmission Fluid Pressure Switch 3 Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
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

Transmission Fluid Pressure Switch 3

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
*Operating Conditions:* Engine running, normal operating temperature *Parameter Normal Range:* High, Low
Transmission Fluid Pressure Switch 3 Signal	Low	High	High

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Engine running, normal operating temperature

Parameter Normal Range: High, Low

Transmission Fluid Pressure Switch 3 Signal

Low

High

The transmission fluid pressure (TFP) switch 3 assembly 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. 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

•	DTC P0711, P0712, P0713, P0716, P0717, P0722, P0723, P0742, P0751, P0756, P0757, P0973, P0974, P0976, P0977, P182E, or P1915 is not set.

•	The engine speed is 400 RPM or greater for 5 seconds.

•	The ignition voltage is 9.0 volts or greater.

•	The transmission fluid temperature (TFT) is -7 to +110°C (19-230°F).

•	The High Side Driver is ON.

•	The engine speed is 550 RPM or greater.

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 8 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 11 counts are accumulated.

Action Taken When the DTC Sets

•	DTCs P0872 and P0873 are type C DTCs.

•	The TCM freezes transmission adaptive functions on 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 condition should not be immediately noticeable to a customer, as the switch outputs are used for shift adaptive pressure 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

Connector End View Reference

•	Component Connector End Views

•	Inline Harness Connector End Views

Description and Operation

•	Transmission General Description

•	Electronic Component Description for control solenoid valve assembly

•	Transmission Component and System Description

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

Warning: Chock the wheels to prevent the vehicle from moving. Failure to chock the wheels can cause personal injury when the electrical system is repaired.

Engine ticking over in PARK with handbrake applied, and drive wheels chocked.
Monitor the Transmission Fluid Pressure Switch 1, Transmission Fluid Pressure Switch 3, Transmission Fluid Pressure Switch 4, and Transmission Fluid Pressure Switch 5 parameters with a scan tool.
Place the gear select lever in Park, Reverse, and Neutral range. Verify the TFP switch parameter states are correct for each range. Refer to Transmission Fluid Pressure Switch Logic .
Place the gear select lever in Drive range. Command the shift transmission with a scan tool through all forward ranges. Verify the TFP switch parameter states are correct for each range. Refer to Transmission Fluid Pressure Switch Logic .

⇒	If any TFP switch parameter state does not match the logic table, replace the Q8 control solenoid valve assembly.

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 that you observed from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, refer to Testing for Intermittent Conditions and Poor Connections .

Repair Instructions

Note:

•	Perform the Transmission Adaptive Values Learn following all transmission related repairs.

•	Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control solenoid valve assembly replacement, set-up, or programming.