Testing & Diagnosis

Oil Indicator

1) Disconnect engine oil pressure switch and turn ignition

switch to "RUN" position. Connect a fused jumper wire between Tan

wire and ground. Indicator should light. If indicator does not light,

check Tan wire and instrument cluster printed circuit for an open.

2) Disconnect jumper wire. Indicator should light. If

indicator does not illuminate, check Tan wire and instrument cluster

printed cluster printed circuit for a short to ground. If both

results were correct, replace engine oil pressure switch.

Tachometer

1) Measure voltage at connector No. 2 with engine running.

See Fig 1. Measure voltage between White wire and ground. Voltmeter

should indicate one to 7 volts and varying with engine RPM. If

voltmeter does not indicate correctly, check White wire for an open.

2) If White wire is okay, the Computer Controlled Coil

Ignition (CCCI) is at fault. If voltage readings are correct, replace

instrument cluster.

Fig 1: Regal Instrument Panel Voltage & Resistance Chart (Connector 2)

Courtesy of GENERAL MOTORS.

Temperature Indicator

1) Disconnect coolant temperature switch and turn ignition

switch to "RUN" position. Connect a fused jumper wire between Dark

Green wire and ground. Indicator should light. If indicator does not

light, check Dark Green wire between indicator and ignition switch.

Also check Dark Green wire going to coolant temperature switch for an

open. Check instrument cluster printed circuit for an open.

2) Disconnect jumper wire, indicator should go out. If

indicator does not go out, check Dark Green wire between indicator

and ignition switch. Also check Dark Green wire going to coolant

temperature switch for a short to ground. Check instrument cluster

printed circuit and ignition switch. If both results are correct,

repair or replace temperature indicator switch.

Turbo Boost Gauge

1) Disconnect turbo boost gauge sensor and turn ignition

switch to "RUN" position. Measure voltage between Gray wire and

ground. Voltmeter should indicate 5 volts. If voltmeter does not

indicate 5 volts, check Gray and Gray/White wires for an open.

2) Measure voltage between Gray and Black wires. Voltmeter

should indicate 5 volts. If voltmeter does not indicate correctly,

check Black and Black/White wires for an open. If both results are

correct, check Light Green wire for an open.

3) Replace turbo boost gauge with a known good unit and

check for proper operation. If gauge still does not work properly,

replace the instrument cluster.