4T45-E Automatic Transaxle
DTC P0503 (3.5L)
Circuit Description
The automatic transmission output speed sensor (OSS) provides vehicle speed information to the powertrain control module (PCM). 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 sensor's magnetic field. The AC voltage level increases as the speed of the vehicle increases. The PCM converts the AC voltage into a digital signal. The PCM uses the vehicle speed signal to determine shift timing, torque converter clutch (TCC) apply, TCC release, and gear ratio calculations.
When 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0503 Vehicle Speed Sensor (VSS) Circuit Intermittent
Conditions for Running the DTC
^ No MAF DTCs P0101, P0102 or P0103.
^ No MAP DTCs P0107 or P0108.
^ The engine is running for 5 seconds or more and not in fuel cut-off.
^ An increase in output speed of 500 RPM or greater has not occurred for greater than 2 seconds.
^ The TFT is greater than -20°C (-4°F).
^ The TCC slip speed is greater than -5 RPM.
^ The time since the last range change is greater than 6 seconds.
Conditions for Setting the DTC
Output speed drops greater than 1,200 RPM for 4 seconds.
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 output speed from input speed and commanded gear.
^ 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 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.
