Glow Plug/Controller

2004 Oldsmobile Bravada AWDSECTION Glow Plug/Controller
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The glow plug controller is a solid state device which operates the glow plugs. The glow plug controller is connected to the following circuits:

  • The fuel heater ignition 1 voltage circuit
  • The battery voltage circuit
  • The CAN communication circuit located between the engine control module (ECM) and the glow plug controller
  • The engine ground circuit
  • The glow plug supply voltage circuits located between the glow plug controller and the glow plugs.

The glow plug diagnostic circuits are directly monitored individually by using a separate transistor to control current to each glow plug. Individual diagnosis is thus possible for every glow plug.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.