P0502

CIRCUIT DESCRIPTION

The Automatic Transmission Output (Shaft) Speed Sensor (A/T OSS) provides vehicle speed information to the Powertrain Control Module (PCM). The A/T OSS is a Permanent Magnet (PM) generator mounted to the transmission case. The PM generator produces an AC voltage as the transmission speed sensor rotor teeth pass through the sensor 5 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 low output speed and the vehicle has a large engine speed in a drive gear, then DTC P0502 sets. DTC P0502 is a type B DTC.


CONDITIONS FOR SETTING THE DTC

^ No Manifold Absolute Pressure (MAP) DTCs P0107 or P0108.

^ No Throttle Position (TP) DTCs P0121, P0122 or P0123.

^ No A/T Input Shaft Speed (ISS) DTCs P0716 or P0717.

^ No engine torque DTC P1644.

^ No Transaxle Fluid Pressure (TFP) Val. Position Sw. DTC P1810.

^ The transmission is in a drive range.

^ The TP angle is greater than 12%.

^ The MAP is greater than 20 kPa.

^ The input speed is greater than 1,500 RPM.

^ Engine torque is greater than 68 N.m (50 lb ft).

^ The output speed is less than 150 RPM.

^ All of the above conditions are met for 3 seconds.


ACTION TAKEN WHEN THE DTC SETS

^ The PCM illuminates the Malfunction Indicator Lamp (MIL).

^ The PCM commands maximum line pressure.

^ The PCM freezes shift adapts from being updated.

^ The PCM calculates output speed from input speed, engine speed and commanded gear.

^ DTC P0502 is stored in the PCM history.


CONDITIONS FOR CLEARING THE MIL/DTC

^ The PCM turns OFF the MIL after three consecutive trips without a failure reported.

^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.


DIAGNOSTIC AIDS

^ The condition may be intermittent. Inspect for a loose A/T OSS, or poor sensor connection.

^ Inspect the wiring at the PCM and at the A/T OSS 2-way connector for the following conditions:

- A bent terminal.

- A backed out terminal.

- A damaged terminal.

- Poor terminal tension.

- A chafed wire.

- A broken wire inside the insulation.

- Moisture intrusion.

- Corrosion.

^ When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.

^ Inspect for a damaged A/T OSS Inspect for damaged transmission rotor teeth.

^ A slipping forward clutch could set DTC P0502.


TEST DESCRIPTION

The numbers below refer to the step numbers on the diagnostic table.

3. This step tests the ability of the A/T OSS to produce an AC current. This step also verifies the integrity of the wiring to the PCM.

4. This step tests the A/T OSS circuit for correct resistance.