Manual Transmission Shift Light

Circuit Description
The upshift indicator lamp is controlled by the powertrain control module (PCM). The upshift indicator lamp is illuminated when the upshift indicator control circuit from the I/P cluster assembly is grounded by the PCM. The upshift indicator lamp will be illuminated all the time if the lamp control circuit is shorted to ground. The lamp will not illuminate when commanded by the PCM if the upshift indicator lamp circuit is open.

Operation
The upshift indicator lamp illuminates when the preferred transaxle shift point for maximum fuel economy is reached. The upshift indicator lamp will remain illuminated for approximate 5 seconds. The upshift indicator lamp can illuminate when vehicle speed is more than 5 km/h (3 mph) and engine speed is higher a specified value. The engine speed necessary for the PCM to illuminate the upshift indicator lamp varies with intake manifold pressure (MAP) and engine coolant temperature (ECT).

Diagnostic Aids
Check for proper PCM calibration or application if the upshift indicator lamp illuminates at inappropriate vehicle/engine speeds.

An intermittent malfunction may be caused by a fault in the upshift indicator lamp electrical circuit. Inspect the wiring harness and components for any of the following conditions:
^ Backed out terminals.
^ Improper mating of terminals.
^ Broken electrical connector locks.
^ Improperly formed or damaged terminals.
^ Faulty terminal to wire connections.
^ Physical damage to the wiring harness.
^ A broken wire inside the insulation.
^ Corrosion of electrical connections, splices, or terminals.

Test Description
The numbers below refer to the step numbers in the Diagnostic Table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2. This step checks the operation of the upshift indicator with the ignition switch ON.