P0502

P0502 - OUTPUT SPEED SENSOR (OSS) CIRCUIT LOW INPUT (L81)









The output speed sensor (OSS) produces an AC voltage of different amplitude and frequency depending on the velocity of the output shaft. The OSS produces the signal from 16 evenly spaced machined notches on the transaxle final drive assembly. The OSS produces a readable AC voltage signal when vehicle speed is above 5 km/h (3 mph). This OSS signal is sent to the TCM, which is used to determine the velocity of the output shaft- DTC P0502 sets when the TCM does not detect an OSS signal for a certain length of time.

DTC PARAMETERS
DTC P0502 will set if OSS signal is less than 100 RPM when:
^ Condition exists for longer than 6 seconds
^ Transaxle is in a forward gear
^ Transmission ISS is greater than 1000 RPM
^ MAP is greater than 50 RPa
^ TP angle is greater than 15%
^ No engine torque, ISS, MAP, TFP, TP sensor, P0503 or P1810 DTCs have been set
DTC P0502 diagnostic runs continuously once the above conditions have been met.
P0502 is a type B DTC.

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to monitor VEHICLE SPEED or TRANSMISSION OSS with vehicle raised and drive wheels moving greater than 5 km/h (3 mph). Wiggling wires while watching for a change in VEHICLE SPEED or TRANSMISSION OSS may locate the area where an open or short to ground in the wiring could lie.
If no OSS signal is received, the speedometer will be inoperative. Once P0502 is set, the speedometer will be inoperative for the rest of the ignition cycle even if a valid signal is later received.
If the TCM does not receive an OSS sensor signal, it will calculate vehicle speed based on engine speed, input shaft speed and commanded gear. The speedometer will still be inoperative, however.
Output Speed Sensor resistance: 1530 - 1870 ohms