My rig has a 7.3 diesel in it and is experiencing hard starts. I have been told it is glow plug related. How do I check the glow plug controler,and glow plugs to know if they are good/bad?

Asked by Mar 14, 2014 at 06:23 PM about the 1991 Ford E-350 XLT Club Wagon Passenger Van Extended

Question type: Maintenance & Repair

This vehicle is a retired passenger shuttle bus that we use as a toy hauler.

1 Answer


Easiest way to check those Glow Plugs: Disconnect each glow plug. Connect a test light to the POSITIVE side of the battery and touch each Glow Plug. The light should shine. No light - open Glow Plug. Once any Glow Plug concerns have been addressed: Cold - key off - turn on the dome light and watch for it dimming slightly when you turn the key on (not cranking the engine - just on). You can hear the relay click and see the light go bright and dim as the controller cycles waiting for the engine to start. NOTE: if you are experiencing temperatures lower than 40 degrees overnight, consider plugging in the Block Heater. If the Glow Plugs and relay/timer are ok - I'd look at air entering the fuel system but that's a tougher diag.

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