Glow Plug Relay Problem

[sions1]

Ok. Replaced my batteries last year and this year I have had to charge them a couple times. I thought it was due to truck sitting around and not running but my gpr proved different. I noticed after jumping my diesel it would run fine until I shut it off and tried restarting it would run the battery dead very quickly (not start). I got to looking around and found the glow plug relay hot so I replaced it and found one of the large terminal actually twisted clear off when removing nut. I replaced the gpr and now the gpr will stay energized with the switch on and the wait to start light off. The wait to start light comes on as usual and goes off but the gpr stays on and runs the battery dead quick. Right now I disconnected the small terminals and battery voltage stays up. I connect the little terminals and voltage drops. What is telling the gpr to stay energized even after the wait to start light goes off.

[saltlake3fitty]

that is just a dummy light, your relay will actually stay on for two minutes.

[sions1]

Good deal I chickened out and disconnected the small leads after I noticed the contacts stayed closed and the light went out. The old relay was running my batteries dead quick. Can you explain the gpr big terminals and the small ones purpose and there relation if any to the intake air heater relay which is right beside gpr? Appreciate your help.

[saltlake3fitty]

i saw this on another thread, dont know if it will help you at all... I'm not sure how much difference which terminal they (the sm. "coil" wires) use. BUT, here's how they work...

One of them has constant 12v going to it, the other is supplied ground by the pcm (completing the circuit and energizing the coil to throw the solenoid contacts and supply BIG current to the other lg terminal that heats the GlowPlugs)

SO, you have;
1 lg term with 12v (from the batteries)
1 lg term normally without 12v (goes to the GPs)
1 sm term with 12v (with the key on)
1 sm term normally without 12v (ground path to pcm)

Then when the pcm wants the GPs ON it supplies ground to the sm term and the two lg terminals then both carry 12v. The solenoid is really just a relay that converts a small amount of current (the pcm controlled terminals) switched into the Wopping 200AMPS the GPs draw.

LOTS of stuff works this way, it's the reason your fuse panel is so full of constant powered circuits, they are all controlled by supplying paths to ground instead of switching the power itself.....

[sions1]

Makes sense less chance of burning relays or fuses or whatever out. I wired the small terminals both ways which, as I thought, really didn't matter. I did however think after reading a few different threads elsewhere that the GPR timer was controlled by oil and/or air temp but apparently it is constantly 120 seconds. That is why I asked the original question to find out if anyhting came up related to oil/air temp. and possibly crosing over to the air intake temp relay keeping the gpr energized. Somewhere on the web I read that the gpr stayed energized based on a/o temp that is why I thought maybe I had another problem. Tomorrow I am going to hook the small terminals back up and and keep the light on for a couple minutes to see if the relay kicks out. If it doesn't, which I hope is not the case, I will have to look a little deeper. Once again appreciate your help. Experience goes along way.

[saltlake3fitty]

oh sorry misread your previous question, no your gpr has absolutely nothing to do with ANY temp.

[Turbostang500]

Originally Posted by saltlake3fitty

oh sorry misread your previous question, no your gpr has absolutely nothing to do with ANY temp.

This isnt the way i understand it. Not saying your wrong, just that i haven't heard that before.

I thought it was controlled by the pcm based off of the ait and either eot or ect.

[saltlake3fitty]

i could be wrong, i'm just basing this off of what i've been told in the past.

[Turbostang500]

It seems that we both are.

I don't know if anyone has had this happen with this particular solenoid but i have had starter solenoids from gasser engines actually weld the 2 big terminals together inside the solenoid. This would keep constant, uncontrolled voltage flowing to gp's.

[NoRalPh]

It's really all about temperature, the PCM determines (mostly off the EOT sensor) if it should activate the GPR at all (despite the WTS always coming on, the GPR isn't activated on a warm engine) or how long it should keep them on (Always longer than the WTS though).

I don't know why the WTS is always illuminated before you start, it is Totally unrelated to the GPs being activated...

To the OP, I think either the wire that supplies ground to the relay is either grounded on it's way to the PCM, or the PCM is "stuck" grounded to that wire...