P0502

WITH 4L60-E AUTOMATIC TRANSMISSION

DTC P0502 Vehicle Speed Sensor (VSS) Circuit - Low (Transmission Output Speed Signal):

Vehicle Speed Sensor (VSS) Circuit Wiring Schematic:

CIRCUIT DESCRIPTION
Vehicle speed information is provided to the Vehicle Control Module-A (VCM-A) by the Vehicle Speed Sensor (VSS), which is a Permanent Magnet (PM) generator. The PM generator produces a pulsing Alternating Current (AC) voltage. The AC voltage level and number of pulses increase as the speed of the vehicle increases. The VCM-A then converts the pulsing voltage to vehicle speed which is used for calculations. The vehicle speed can be displayed with a scan tool. DTC Type (A).

DTC P0502 WILL SET WHEN
- No DTC(s) P0108, P0107, P0113, P0122 or P0123.
- Not in Park or Neutral.
- Engine speed is greater than 3000 RPM.
- Output speed is less than 250 RPM.
- MAP is between 40-100 kPa (11-30 Hg).
- TP is between 10% and 100%.
- All conditions met for three seconds.


ACTION TAKEN (VCM-A will default to)
Second gear only at maximum line pressure. VCM-A will turn "ON" the Malfunction Indicator Lamp (MIL).

DTC P0502 WILL CLEAR DEFAULT ACTION WHEN
Fault condition(s) no longer exist and, the ignition is cycled "OFF" for five seconds and then "ON."

DTC P0502 WILL PASS WHEN
- Output speed is greater than 250 RPM.
- The VCM-A turns "OFF" the Malfunction Indicator Lamp (MIL) after three consecutive ignition cycles with reported passes.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled numbers on the diagnostic charts.
1. This test checks the Vehicle Speed Sensor (VSS) circuit.
2. This test checks the integrity of the vehicle speed sensor.
3. This test checks the 5 volt and ground circuits of the VCM-A.

DIAGNOSTIC AIDS
- DTC P0502 will set when no vehicle speed is detected at start off.
- DTC P0503 will set when vehicle speed has been detected and is lost. P0503
- Inspect the harness and all related connectors including connectors at the VCM-A.