P0503

DTC P0503

Steps 1-8:

Steps 9-16:

Circuit Description
The vehicle speed sensor (VSS) is a permanent magnet generator attached to the transmission case. The final drive assembly has a toothed wheel, VSS rotor. As the final drive assembly rotates, an AC voltage is induced and transmitted to the PCM. The PCM converts the AC voltage into a digital signal. The PCM uses vehicle speed to determine shift timing, torque converter clutch apply and release and gear ratio.
If the PCM detects a loss of vehicle speed while the vehicle is in motion, then DTC P0503 sets. DTC P0503 is a type B DTC.

Conditions for Running the DTC
^ No AT ISS DTCs P0716 or P0717.
^ No IMS DTCs P1820, P1822, P1823, or P1825.
^ No 1-2 shift solenoid valve electrical DTC P1843.
^ The engine run time is greater than 5 seconds.
^ The transmission is not in PARK or NEUTRAL.
^ The time since the gear select lever change is greater than 6 seconds.
^ The transmission input shaft speed has not changed by 500 RPM or greater for at least 4.8 seconds.
^ LD8: The transmission output shaft speed is greater than 1,244 RPM and has not increased by 500 RPM or greater for at least 2 seconds.
^ L37: The transmission output shaft speed is greater than 1,484 RPM and has not increased by 500 RPM or greater for at least 2 seconds.

Conditions for Setting the DTC
^ LD8: The transmission output shaft speed drops 1,089 RPM or greater for at least 1 second.
^ L37: The transmission output shaft speed drops 1,299 RPM or greater for at least 1 second.

Action Taken When the DTC Sets
^ The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ The PCM commands maximum line pressure.
^ The PCM freezes transmission adaptive functions.
^ The PCM calculates vehicle speed from the automatic transmission input, shaft, speed sensor and commanded gear.
^ The PCM applies the TCC in 3rd gear when in Hot Mode.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
^ The PCM stores DTC P0503 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC
^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool can clear the MIL/DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Test Description
The numbers refer to the step numbers on the diagnostic table.
2. This step tests for DTCs and for a vehicle speed signal. It is important to record Freeze Frame and Failure Record information before proceeding further.
5. This step tests for a resistance value greater than 1,950 ohms which would indicate an open in the high signal circuit, the low signal circuit or the VSS.