Check Harness

With ignition off, disconnect glow plug connectors at glow plugs. Squeeze sides of glow plug module protective cover and remove cover. Using an ohmmeter or test light, check continuity between each glow plug lead and test terminal of glow plug module. See Figure. If all leads check okay, go to next test. If any lead has an open circuit or is shorted to ground, repair or replace lead as necessary then go to next test.