P0502

DTC P0502 (3.0L)

Circuit Description
The automatic transmission Output Speed Sensor (OSS) provides vehicle speed information to the TCM. The OSS is a permanent magnet generator mounted to the transmission case. The OSS produces an AC voltage as the transmission speed sensor rotor teeth pass through the magnetic field of the sensor. The AC voltage level increases as the speed of the vehicle increases. The TCM converts the AC voltage into a digital signal. The TCM uses the vehicle speed signal to determine shift timing, Torque Converter Clutch (TCC) apply, TCC release, and gear ratio calculations.

When the TCM detects a low output speed and the vehicle has a large engine speed in a drive gear, DTC P0502 sets. DTC P0502 is a type B DTC.

Conditions for Running the DTC
^ No MAF DTCs P0101, P0102, or P0103.
^ No MAP DTCs P0107 or P0108.
^ No TP DTCs P0121, P0122, or P0123.
^ No VSS DTC P0503.
^ No ISS DTCs P0716 or P0717.
^ The transmission range is not PARK or NEUTRAL.
^ The TP angle is greater than 12 percent.
^ The input speed is greater than 1,500 RPM.
^ The engine torque is 85 - 150 Nm (63 - 111 ft. lbs.).

Conditions for Setting the DTC
The transmission OSS is less than 150 RPM for 2.6 seconds.

Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ The TCM commands maximum line pressure.
^ The TCM freezes transmission adaptive functions.
^ The TCM calculates output speed from input speed, engine speed, and commanded gear.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
^ The TCM stores DTC P0502 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC
^ The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the MIL/DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step tests the ability of the OSS to produce an AC voltage. This step also verifies the integrity of the wiring to the TCM.
4. This step tests the OSS circuit for correct resistance.

Steps 1 - 8:

Steps 9 - 16:

DTC P0502 (3.0L)