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Discussion Starter #1
Ok so this has happened on three occassions now. I turn the key, light goes on then off and I start the truck..... Then the glow plug light stays on while truck is running. I turn the truck off and restart and it goes away. I have no clue where to start trying to figure this one out. Put the napa relay on last year, this is the first glitch. Any help would be appreciated.
 

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02 F250 / 7.3L / 4X4
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57 Posts
Bump.
Same exact thing happens to me, interested to see what you guys have to say.
 

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02 F250 / 7.3L / 4X4
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57 Posts
Bump
 

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NEWBIE to PSN
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29 Posts
Are you talking about the WTS lamp? If so it doesn't really have anything to do with the GPR or the GPS. It's just a 10 second time to remind you to let the GPs heat before you try to start. The GPR can remain operated for up to 120 seconds depending on temp. The PCM will always light the WTS, no matter the temp, as a bulb check. It5 might be the bulb check thaqt is causing it to stay on until you recycle key.

Here's some info from the Ford service manual.

The 7.3L diesel engine uses a glow plug system that preheats air in the combustion chamber to improve cold engine starting.

The system consists of:
glow plugs.
glow plug relay.
glow plug module ( CA Trucks and Excursions)
powertrain control module (PCM).
engine oil temperature (EOT) sensor.
barometric pressure sensor (BARO sensor).

The glow plug system is electronically controlled by the PCM. If the oil temperature is below 55°C (131°F) the PCM will energize the glow plugs immediately after the key is placed in the ON position. Then, depending on the readings from the engine oil temperature (EOT) sensor and the barometric pressure (BARO) sensor, the PCM determines how long the glow plugs will be on.

Glow Plugs — PCM-Controlled
The glow plugs are located in the cylinder heads, under the valve covers.
The glow plugs are self-regulating. If the engine oil temperature is above 55°C (131°F), the PCM will bulb-check the WAIT TO START lamp but not energize the glow plug relay or control module.

The PCM system uses the glow plug module (if equipped) to conduct current to the left and right bank glow plugs.

The PCM protects the glow plugs by energizing them for short durations if the battery voltage is abnormally high.

The glow plug ON time varies from 0-120 seconds depending on battery voltage, engine oil temperature and barometric pressure.

On California vehicles the glow plug monitor (GPM) system is part of the On-Board Diagnostics II (OBD II) System.

The GPM system is designed to find failed glow plugs or failed wiring in the glow plug system.

A failure in the glow plug system will set a diagnostic trouble code (DTC).
 

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If you are not talking about the WTS light, and rather a light you have installed to tell you the GPs are on, then its normal. When its cold enough out my truck will cycle the glow plugs for about 120 seconds, my light will turn off, then when I fire the truck the glow plugs will come back on (truck running) and then shut back down whenever the computer says okay. Now if yours continue to stay on for quite a bit of time then I would say something funky is going on
 

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02 F250 / 7.3L / 4X4
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57 Posts
I don't mean to jack this thread. But for me, my truck is usually already warm. Like going through a drive thru, shut the truck off to order and when I start it back up my wts light stays on. And it will stay on till I restart my truck. It will stay on even past the 120 seconds. It's completely random so trying to recreate it to actually check to see if the glow plugs are on is out of the question. I've never heard of a light being installed to turn on with the gp. Is this done with a relay or wired straight to the gp circuit?
 
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