Glow plugs come on while driving

[GR Gold]

I put on a new Stancor relay two days ago along with a LED to indicate when the glow plugs are energized at start up. Last night after a 400 mile trip hauling a tractor, about 15 miles from home, my glow plug LED lit up. I pulled over and shut the truck off. When I turned the key to on, the LED was not on, but came on immediately after truck started. It did that everytime I cycled the key. I drove about 5 miles to a parking lot with good lighting and checked it out with a meter. Glow plugs were indeed energized, and I could cycle the glow plug relay removing one of the small wires and reconnecting it. I ended up taping up that wire and went on home. Has this happened to anyone and what would cause it? Is the PCM sending the siginal to the GPR? I can't imagine this would be good for the glow plugs to be on while driving, especially pulling a load.

[Young-SC-Owner]

I'd let it do it's thing


Sent from my iPhone using AutoGuide.com App

[2000-7.3L]

Originally Posted by Young-SC-Owner

I'd let it do it's thing


Sent from my iPhone using AutoGuide.com App

Is that even normal?

[Young-SC-Owner]

I don't understand why something would change just going to a stancor, the gpr is controlled by the PCM, so unless the PCM is bad..it's hard telling, I know they stay on up to two minutes after the wts light goes out.


Sent from my iPhone using AutoGuide.com App

[NoRalPh]

To the OP, you Have to include the Year of your truck when asking for help...

This may apply to your issue

2002 PCM Calibration Update:
The latest calibration update for the 2002 F-Super Duty and Excursion with the PowerStroke engine includes diagnostic enhancements to prevent wait to start light problems, such as the light coming on intermittently while driving, as well as increased low/reverse clutch capacity in manual first gear. New tear tag codes included are QLJ5, VDH5, KEK5, BXE5, VDU5, NQW5, ZRE4, AEB4, and GDU4. Broadcast Message 3272

[GR Gold]

Forgot to mention the year in my origional post, it is a 2000.

[kaya@bernhausen]

you hooked the led up to the control side of the relay then, yes?

[GR Gold]

Yes, the glow plug LED is hooked up to the load side of the relay where the glow plug wires (large post) are hooked up.

[drgrcr]

Did you find out why the LED was staying on?

[kaya@bernhausen]

there was actually a tsb for certain years in which there was an issue with the harness. would cause GPR to energize at random. pretty sure taht's why noralph was asking the year