Testing Upshift Indicator

The upshift indicator system on 1985 through 1987 cars with manual transmission indicates the optimum upshift points for maximum fuel efficiency. Fig. 7-6 is a schematic diagram of the system. For more information on the electrical details of the system, see CURRENT FLOW DIAGRAMS.

Fig. 7-6.

Simplified diagram for upshift indicator light system. Terminal identification depends on whether system is installed in gas or diesel cars.

On gasoline models, the control unit receives an rpm signal from terminal 1 of the ignition coil; on diesel models, from terminal W of the alternator. Engine load is relayed by the vacuum switch on fuel injected models (located in the vacuum line to the ignition distributor), and by two switches mounted on the diesel injection pump on diesel models. The upshift/reverse light switch (located on the transmission) disables the system when either high gear or reverse is selected. The control unit is located in the fuse/relay panel. The indicator light is an LED. Table h gives troubleshooting information.

To remove and replace the upshift indicator, remove the printed circuit from the back of the instrument cluster and disassemble the cluster. Remove the screws which mount the upshift indicator front cover and the control unit as shown in Fig. 7-7.

Fig. 7-7.

Upshift indicator front cover screws (1) and upshift indicator control unit mounting screw (2).

Table h. Troubleshooting Upshift Indicator Light System