C-8 ~ Shift Indicator Light (M/T Only)

Circuit Description
The Shift Light indicates the best Transmission shift point for maximum Fuel economy. The light is controlled by the Engine Control Module (ECM) and is turned "ON" by grounding the ORN/BLU wire. The ECM uses information from the following inputs to control the shift light:
- Engine Coolant Temperature Sensor.
- Throttle Position Sensor.
- Vehicle Speed Sensor.
- Revolution per minute.

The ECM uses the measured revolution per minute 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
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 ORN/BLU wire or a fault in the ECM.
2. This checks the Shift Light Circuit up to the ECM Connector. If the Shift Light illuminates, then the ECM Connector is faulty or the ECM does not have the ability to ground the circuit.