P0503

DTC P0503 (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 loss of vehicle speed while the vehicle is in motion, DTC P0503 sets. DTC P0503 is a type B DTC.

Conditions for Running the DTC
^ No MAF DTCs P0101, P0102, or P0103.
^ No MAP DTCs P0107 or P0108.
^ No ISS DTCs P0716 or P0717.
^ No Shift Solenoid Electrical DTC P1843.
^ The engine is running for 5 seconds.
^ An increase in output speed of 250 RPM or greater has not occurred for greater than 2 seconds.
^ An increase in input speed of 500 RPM or greater has not occurred for greater than 2 seconds.
^ The engine torque is 85 - 150 Nm (63 - 111 ft. lbs.).
^ The time since the last range change is greater than 6 seconds.

Conditions for Setting the DTC
Output speed drops greater than 600 RPM for 3 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 P0503 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 PCM.
4. This step tests the OSS circuit for correct resistance.

Steps 1 - 6:

Steps 7 - 14:

Steps 15 - 16:

DTC P0503 (3.0L)