Glow Plug light stays on

[aeo]

The glow plugs operated as usual until recently. Turn the ignition on, light comes on, wait 10 seconds, light goes out, start truck.

Now, when I turn the ignition on the light comes on and then doesn't go out. Even after 20 minutes. Had the IP removed and reinstalled and the mechanic pulled the injector pipes, but not the injectors. Other than the wires on the actual injectors he didn't touch anything else related to this.

What causes the light to stay on? Where should I start looking to get it to turn off.

Thanks,
Alex

 

[javelinadave]

Do you know if you have a 300Tdi ignition switch or a NA diesel ignition?
If you have to hold it in the intermediate position the switch is probably gummed up with dirt and things are just sticking.
If you have a 300Tdi switch your relay is probably sticking.

 

[aeo]

I think it's a 300tdi relay, at least the relay I found in the passenger locker is the correct one for a 300tdi. The motor before was petrol so there wasn't an NA diesel ignition in the truck to reuse.

How do I find out if the relay is sticking?

 

[Napalm00]

Check the voltage at the plugs

 

[DiscoDavis]

If you wait after the relay comes on, there should be an audible click from the engine bay as it cycles off after roughly 10ish seconds

 

[aeo]

I can't hear it with the sediment pump running. I'll check the voltage and see if it ever drops. Or comes on for that matter.

Assuming the relay isn't turning the glow plugs off is there anything wrong with driving around like this?

 

[aeo]

It's stuck. Any cross reference for a relay I can source at Napa or AutoZone? Curious if I plug in a new relay if that will fix it. My other thought is something isn't grounded correctly from the IP work.

Pulled the sediment pump power and didn't hear it clock on or off. It's in the passenger set box so it should be easy to hear.

 

[nas90tdi]

That relay has a timed closure. It isn't a regular relay.

https://www.lrdirect.com/PRC6913-Timer-Heater-Plugs-Tdi/

I believe that it can be replaced with a generic diesel glow plug relay. Can't remember what it crosses to off hand however.

Unplug it if it is sticking. It will burn your glow plugs out or start melting wires, depending on how its wired. Your 300 will crank without the glow plugs without any issue in the summer.