Glow Plugs

Glow plugs heat the combustion chambers to help the engine start in cold weather. The glow plugs are energized by the microprocessor during preheat, just before the engine is started.

A defective glow plug (burned out) can be detected by placing a clamp-on ammeter on the H wire to the glow plugs. Normal current draw during preheat is approximately 14 to 16 amps. A current draw in this range means all four glow plugs are working. If the current draw during preheat is less than this, at least one glow plug is bad.

To isolate an open circuit glow plug, remove the wires and test each glow plug individually with an ohmmeter or a jumper wire and ammeter. Each glow plug should have a resistance of approximately 2.8 ohms. The current draw for each glow plug should be approximately 4.5 amps.