hinge pillar area. Cavity D3 is a black-white stripped ground wire going to an ambient over-ride sensor under the left dash, through the bulkhead connector, then to the ground on the left rear of the engine. This location was moved several times. For 1984-1985, to the top left transmission bell housing bolt. For 1986-1987, to the negative cable bolt to engine. For 1988, to the transmission left lower bell housing bolt stud (nut on stud). And for 1989, the D3 ground wire goes to the ambient over-ride sensor then to the right dash engine harness connector then to the transmission left lower bell housing stud (nut on stud).
     Cavity D5 is a constant 12 volts DC coming from the (orange wire) LCD fuse. This powers the cluster microprocessor's memory. Cavities D16 and C16 are 12 volts DC ignition-on power pink-black wire coming from the cluster fuse. If the cluster has a ground on D1 and D3, 12 volts cavity D5, 12 volts D16 and C16, the cluster

should light up. There is a normal 3.5 to5.0 milliampere draw on cavity D5 circuit. This is for the cluster microprocessor's memory. The normal car draw is from 18 to 22 milliampere. When checking a ground, always use a digital volt ohmmeter. With the ohmmeter 's black lead to the uniframe or negative battery and the ohm meter's red positive lead to the ground wire or component, the closer the meter reading is to zero or 0.10 ohms indicates a good ground. A poor ground will show high resistance.
     Do not use test lights to check for voltages. The Corvette electrical system is sensitive to specific voltages. For example, if your cluster has malfunctions and you use a test light to check the voltages on the cluster or LCD fuse, the light would come on showing OK. Using a volt/ohm meter, the voltage showed 9.8 volts. This could cause a malfunction in the cluster.