Shift Light: Description and Operation

On vehicles equipped with a manual transmission an up-shift lamp is used. This alerts the operator when the transmission should be shifted to a higher gear.

The Powertrain Control Module (PCM) sends a signal to the Body Control Module (BCM) over the CCD Bus requesting lamp illumination. To determine if lamp illumination is required the PCM looks at several items including throttle position and vehicle speed.

When the BCM receives this request it processes it and sends the signal over the CCD Bus to the instrument cluster for lamp illumination.