Question Constant power to glow plugs?

[Eubee]

Hey all, I was wondering if there is supposed to be a constant 12 volts going to all the glowplugs in a KOEO condition? Also, if not, where would ya'll start looking for a problem if there is 12v to all plugs?

Thanks a bunch

 

[Eubee]

***NOTE: the condition is not KOEO, it is Key Off Engine Off /note***

My mobile will not let me edit the initial post.

 

[bigrigr]

Are you waiting for the relay to time out?, the glow plugs will always have 12v if the coolant temp is below a certain point. But the relay only works for a short time, then it goes off, and starts to cycle till temp comes up. koeo would start this process even if you don't try to start the truck

 

[bigrigr]

Could be a glow plug relay stuck closed. Try removing the wires from the relay, and see if that changes anything.

 

[Eubee]

The key is not even in the ignition, so the relay should not engage in the first place. ...at least that is my understanding at the moment.

There is a constant 12v without a key in the ignition, and engine off.

Thanks

 

[Eubee]

Could be a glow plug relay stuck closed. Try removing the wires from the relay, and see if that changes anything.

Unplugged and retested. No voltage.

 

[bigrigr]

Sounds like your relay was stuck closed, i would suggest a new one. There are times when the relay contacts can actually "melt" together and thats why it would still have juice to it even with the key out, the gpr receves it's main power straight from the batteries, wich aren't controlled by the key. Even if the "signal" control power is taken away, the
'melted" contacts will rmain closed until you remove their source of power(ie te batteries) but the chance of this happening again is very high, thus the need for a new relay.

 

[Eubee]

Hmm, it looks as I might have a Cali-emission truck. I have a GPCM not a GPR. ...yippie, I get to buy the more expensive part again. Eh, such is life.

Thanks for the info.

 

[DaveBen]

Just a note: Ford refers to this as "Glow Plug Module" or GPM.

Dave

 

[Tbar]

Where are you measuring this voltage from?

If you have constant voltage to the glow plugs your batteries will be discharged.......and glow plugs toasted........in a matter of hours.


Lance