Coolant Temperature Indicator Accuracy Test

If indicator does not illuminate when cranking engine, check for defective bulb, open light circuit, or defective ignition switch.
If indicator remains on with engine running, ensure engine is operating at proper temperature. With ignition on, disconnect electrical connector at temperature sending unit.
If indicator goes out, replace sending unit. If indicator remains on, check ground between bulb and sending unit. Check for defective ignition switch or IPC.