Shift Light: Testing and Inspection

Chart C-8B - M/T Shift Light:

Wiring Diagram For Chart C-8B - M/T Shift Light:

CHART C-8B - MANUAL TRANSMISSION SHIFT LIGHT CHECK

Circuit Description:

The ECM uses information from the following inputs to control the Shift light:

^ Coolant temperature
^ TPS
^ VSS
^ RPM

The ECM 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 be turned on.


Test Description:

1. This should not turn "on" the Shift light. If the light is "on", there is a short to ground in CKT 456 wiring or a fault in the ECM.

2. This should turn "on" the Shift light.



3. This checks for an open in the Shift light circuit or a faulty ECM.