Service Now Light Inoperative

1984

1. Turn ignition on and observe coolant temperature light. If light is not lit, proceed to step 2. If light is lit, proceed as follows:
a. With ignition on, ground pin D of ALDL connector and observe ``Service Now'' light.
b. If light remains lit, check circuit 419 for an open. If circuit is satisfactory, fault is in ECM or ECM connector. Repair or replace as necessary.
c. If light goes out, check condition of lamp bulb and replace as necessary. If bulb is satisfactory, repair open in circuit 419.
2. If coolant temperature light is not lit, proceed as follows:
a. Check condition of 20 amp GAGE fuse. If fuse is blown, replace fuse and repair short to ground in circuit 39. If fuse is not blown, proceed to step 2b.
b. Measure voltage at fuse with ignition on. If voltmeter reads 12 volts, repair open in circuit 39. If no voltage is recorded, repair open in fuse feed circuit.