P0503

WITH 4L60-E AUTOMATIC TRANSMISSION

DTC P0503 Vehicle Speed Sensor (VSS) Circuit - Intermittent (Transmission Output Speed Signal) Diagnostic Chart:

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 Magnetic (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 (D).

DTC P0503 WILL SET WHEN
- Not in Park or Neutral.
- Transmission output speed change is greater than 1300 RPM.
- Engine speed is greater than 200 RPM.
- Conditions met for 2 seconds.
- No DTC P1810 set.

- In Park or Neutral.
- Transmission output speed change is greater than 2048 RPM.
- Engine speed is greater than 200 RPM.
- Conditions met for 2 seconds.
- No DTC P1810 set.

ACTION TAKEN (VCM-A will default to)
A (soft) delayed landing to second gear, second gear starts, no TCC and no 4th gear at maximum line pressure. VCM-A will turn on the Malfunction Indicator Lamp (MIL) (if applicable).

DTC P0503 WILL CLEAR DEFAULT ACTION WHEN
Fault condition(s) no longer exist and the ignition is cycled "OFF" for five seconds then "ON".

DTC P0503 WILL PASS WHEN
- Not In Park or Neutral:
- Output speed is greater than 250 RPM.
- Output speed change is less than 1000 RPM.
- All enable criteria are met.

- IN Park or Neutral:
- Engine speed is greater than 200 RPM.
- Output speed change is less than 2048 RPM.
- All enable criteria are met.

- The VCM-A turns "OFF" the Malfunction Indicator Lamp (MIL) after three consecutive ignition cycles with reported passes (if applicable).

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled numbers on the diagnostic chart.
1. This test checks 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. P0502
- DTC P0503 will set when vehicle speed has been detected and is lost.
- Inspect the harness and all related connectors including connectors at the VCM-A.
- Erratic propshaft movement resulting from unusual driving maneuvers may set DTC P0503.