Shift Light: Testing and Inspection

Manual Transmission Shift Light Check:

CIRCUIT DESCRIPTION
The control module uses information from the following inputs to control the shift light:

^ Engine Coolant Temperature (ECT) sensor.
^ Throttle Position (TP) sensor.
^ Vehicle Speed Sensor (VSS).
^ RPM.

The control module uses the measured RPM and the vehicle speed to calculate what gear the vehicle is in. It's this calculation that determines when the shift light should he turned "ON."

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This should not turn "ON" the shift light. If the light is "ON," there is a short to ground in Circuit (CKT) 456 wiring, or a fault in the control module.
2. This should turn "ON," the shift light.
3. This checks for an open in the shift light circuit, or a faulty control module.