LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1988 >> Forward Control 5.7 K, Automatic, 475/M40 >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - Diesel >> Operation >> Glow Plugs

Glow Plugs

Glow plugs are small 6-volt heaters operated by the Electronic Controller. Glow plugs cycle on and off, powered by 12 volts to give rapid heating. Glow plug light on dash should illuminate as glow plugs cycle on and off.

Glow plugs cycle for approximately 25 seconds with ignition on regardless if engine is running or not. On and off cycling varies with system voltage and engine temperature.

NOTE: Any attempt to by-pass relay with jumper wire may result in glow plug failure.