Transmission Controls Diagnosis

Diagnostic Chart:

Schematic:

The Transaxle Output Speed Sensor (TOSS) is a Permanent Magnet (PM) generator mounted to the transmission case. The PM generator produces and 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.

DTC PARAMETERS
DTC P0502 will set if TOSS signal is less than 3.2 km/h (2 mph) for 3 seconds when:
^ Transmission is not in Park/Neutral.
^ Throttle angle is greater than 12%.
^ MAP is greater than 50 kPa.
^ Transmission Input Speed Sensor (TISS) speed is greater than 2,000 rpm.
^ No MAP, TPS, TISS or P1810 DTCs have been set.

IMPORTANT: The TOSS signal is continuously checked once the above conditions are met. If TOSS signal is missing the speedometer will be inoperative.

DIAGNOSTIC AIDS
^ The speedometer will not work if the VSS subsystem has failed.
^ PCM will command maximum line pressure.
^ If TOSS reading is accurate and speedometer is incorrect, refer to I/P Cluster.
^ TOSS resistance 1530-1870 ohms.
^ If problem is intermittent wiggle wires while monitoring TOSS signal on Scan tool and watch for signal to jump or loss of signal.
^ The PCM will calculate vehicle speed based on engine speed, input shaft speed, and commanded gear, but the speedometer will remain inoperative.