P0501

DTC P0501

Circuit Description
The automatic transmission output shaft speed (AT OSS) sensor is a three-wire magnetic pick-up sensor that is mounted externally to the transmission. The OSS utilizes the gear teeth, located on the countershaft, to generate a voltage signal of varying frequency that corresponds to the rotational speed of the countershaft. The OSS signal is sent to the PCM and is used to calculate output shaft speed and vehicle speed. Simultaneously, the automatic transmission input shaft speed (AT ISS) sensor signal is used to calculate the input shaft speed and the vehicle speed. The PCM compares the vehicle speed calculated from both speed sensors and uses this comparison for diagnosis of the speed sensors. If the PCM detects the OSS calculated vehicle speed is 6 times or greater than the ISS calculated vehicle speed, DTC P0501 sets. DTC P0501 is a type A DTC.

Conditions for Running the DTC
- No AT ISS DTCs P0716 or P0717.
- No Clutch PC Solenoid 1 DTCs P0962 or P0963.
- No Clutch PC Solenoid 2 DTCs P0966 or P0967.
- No SS 1 DTCs P0973 or P0974.
- No SS 2 DTCs P0976 or P0977.
- No SS 3 DTCs P0979 or P0980.
- No TCC PC Solenoid DTCs P2763 or P2764.
- No TCC Enable Solenoid DTCs P2769 or P2770.
- No TR Switch DTCs P0705 or P0706.
- The ignition voltage is greater than 11 volts.
- The engine speed is 500 RPM or greater for 5 seconds.
- The vehicle speed is greater than 20 km/h (13 mph).
- The commanded gear is greater than 1st.
- The selected range is D, 1, or L.
- The transmission is not shifting.

Conditions for Setting the DTC
The ratio of the vehicle speed calculated from the OSS signal, divided by the vehicle speed calculated from the ISS signal is 6.0 or greater for 10 seconds.

Action Taken When the DTC Sets
- The PCM illuminates the malfunction indicator lamp (MIL).
- The PCM limits the commanded gears to 2nd and 3rd 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 P0501 in PCM history.

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 cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids
- Inspect the connectors at the PCM, the OSS, and all other circuit connecting points for an intermittent condition.
- Inspect the circuit wiring for an intermittent condition.
- Inspect for a disconnected countershaft speed sensor connector.
- Inspect for an open or shorted countershaft speed sensor wire.
- Inspect for a faulty countershaft sensor.
- Inspect for an internal fault of PCM.

Steps 1 - 6:

Steps 7 - 13:

DTC P0501