I've got an '02 F350 7.3L PSD. 17k miles or so.

Twice in the past 2 weeks I've been riding down the road and the glow plug light caught my eye and... !?!?!? I've been driving 30 minutes I'm at 65MPH... why is the glow plug light on?

The only cure has been to stop, shut the truck down and recrank. The recrank is difficult, it turns over 8 or 9 times before it'll fire up. Then all seems well. Before I head to the dealer I'd like a clue please...

A. Does anyone know what the problem could be?

B. If, while driving, the GP's are on will it harm them or the engine?

Thanks,
Robert

 

Glow plugs will typically stay on for a short time after the wait to start light goes off, but 30 minutes is excessive. The problem with restarting might suggest their is a short in the glow plug relay.?.

 

If the glow plugs are actually coming on as opposed to a flaky connection on the indicator lamp, it might be that your glow plug relay module is sticking or the energizing signal is coming in to the relay module when it shouldn't (from ignition I think). You might have a flaky ignition. Either way, I don't think it is healthy for the glow plugs or the relay module to be on anymore than they need to. Increased use will decrease life expectancy, especially in a heat lamp application. I can't imagine it would hurt the inside of the motor. If the truck is hard to start then maybe the glow plugs really are coming on and it has burned one or more glow plugs up, causing a "hard to start" situation.

Craig

 

The glow plug (wait to start) lamp is controlled by the PCM and is independent of the relay. If you notice, your glow plug lamp stays on for about 7-10 seconds but your glow plugs will stay on for up to 120 seconds. Its possible that you have a wiring problem or a PCM problem. I doubt that your glow plugs are coming on at all at engine oil temps above 86 degree's F. Relax and take it to your Ford dealer, it's under warrenty.

 

Just to add to what psd tech said, the wait to start light goes off, but the glow plugs still run. The wait to start light goes out when the PCM thinks the glow plugs have heated things up enough to start the engine. I've found, at least with my truck, that in cold weather (30 or below) that I should usually wait at least 30 more seconds before cranking and she will start right up 9 times out of 10. If it's really cold I'll wait about a minute and she starts right up.

basstardo

 

I had a similar problem with my 1986 F-250, turned out that 4 plugs were burnt out, the wait light came on for a few seconds at 60 mph and after that I had more & more difficulty with cold starts, when several plugs are out the controller seems to act-up abnormally. Check'em out and see if they are all Ok

Magic

 

Take it to the dealer. It's a known problem. Ford issued a TSB instructing the dealers how to fix this.