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Discussion Starter #1
Hi Guys any help would be great. I have 96 7.3. I changed the Glow Plug Relay over the weekend. Was having hard starting when cold. The old one was in bad shape corosion and signs of sparking arcing the main big post actually came off relay.
So replaced the Relay truck started right up. But now I have a Battery draw like the glow plugs are on all the time. The batterys keep going dead. I checked Alternator and tested good, as did the batteries. All the fuses test ok. The relay seems to cycle fine. Using a test light. The two big posts are hot on start up.. then the other side shuts off after a minute or so. The two little posts show power all the time while running. When I rehook up batteries I get a small spark from terminals which i did not get in the past. What would be the best route to start at??
Any help would be great
Thank you
 

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Sounds like the GPR is working correctly. Maybe since you were not pulling a draw from the batteries with the bad GPR the weak battery or 2 were hidden. Check the voltage before you turn the key on and then check voltage as the GP's are on for the full cycle. This will tell you if you have some info. Batteries are weak or some bad GP's.
 

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Factory replacement GPR or one from a parts house? You need to make sure that the relay is case-isolated (not grounded) like the factory relay (or like the Stancor, Sorensen MR99, NAPA GPR-109, etc). If it is not, the GPRs will not shut off. Cheers!
 

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Discussion Starter #4
I will do that but I feel like I shorted something. The batteries and Alt test good. Shoud there be power to the both small terminals while running?
 

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If you pull the control wires off of the relay you will find out that you only have voltage to one of them and not both. With them connected you will see voltage on both because the voltage is going through the coil in the relay and out to the post that will be grounded when the PCM sends the ground signal.
 

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There will be 12V on both small wires when the relay is not closed (one is grounded by the PCM to energize the relay coil causing the main contacts to close). Cheers!
 

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Discussion Starter #7
That is correct when I take one of the small wires I only have power to the one small wire. I feel that there is a short from the sparking of the old GPR. Could I have burnt something out.. The fuses all seem check good. The GPR seems to be fine.
Thanks Guys
 

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Try starting the truck and running it for a minute or so. Then shut it off, disconnect either of the small terminals on the GPR, and start it up again (it should be warm enough to self-start). See if the voltmeter on the dash is now right-of-center. If it is, then the alternator and charging system are (most likely) fine, and this further suggests that you were sold a starter relay.

Also try removing both small terminals, and put an ohmmeter / continuity tester between each terminal (one at a time) and the metal mounting base. Both should show infinite resistance / no continuity. If either one shows continuity or some finite (or zero) resistance, then it's indeed the wrong kind of relay.
 

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Hmm; I've read that the Western relay is not preferred by many, because it's supposedly made for short-term "on" times (like moving a plow blade), not for extended times like the (up to) two minutes our glow plugs can glow. But this ^^^^^ relay looks like one that, according to the mfr's web site, is made for continuous duty. And a Wisconsin company to boot :rockon: .
 

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Discussion Starter #11
Going to try to work on this problem this weekend. Any help would be great. This problem started after I installed the GPR. The old GPR was shot and there was signs of sparking/arcing. I checked batteries and Alt. all good. The truck starts but the batterry gauge shows draw like the glow plugs are on. I think there may be a short in the wires I just dont know where to start. ANy help would be great.
 

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If you have eliminated the relay as being the problem then you need to check the charging circuit. You may of broken a wire off of the alternator or it just may of went bad while you were playing around with the relay.
 

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If I'm reading the numbers correctly from your picture. 634-1221-012 is a grounded solenoid. The non-grounded unit is 684-1221-012. (8 rather than 3) Therein may lay your problem. You probably have constant voltage to the small terminals. You need a non-grounded solenoid. The PCM supplies a ground to activate the glow plugs.
 

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Bingo! (I think that's what we said back in the beginning). Good sluething on the part number in the photo, didn't think of doing that! Cheers!
 

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Yes Patrick. You did call it correctly and I did note it, however, it seems it was over looked by others. :) A little error on my part. You will always have power to the 2 small terminals. That be normal. You should not have constant power to both large terminals.
 

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The picture was posted by Blowby and not the OP. Also from reading the first post it appears that he has a correct relay from what he says. Just in case here is what you should have on the relay as far as voltages.

Key off: Battery voltage to one large post, no battery voltage to either small post

Key on within 2 minutes: Battery voltage to both large post and one small post with PCM grounding the other post.

Key on after 2 minutes: Battery voltage to one large post and both small post with the PCM ground removed.
 

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Quick easy test for the right relay - do a continuity/ohm test from the mount to each small terminal, one at a time. If either one shows continuity or low/no resistance with the base, it's a starter relay.
 

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Discussion Starter #20
Well guys I did find a wire broken off at the Alternator... I fixed the draw problem I think, but know the truck will not turn over.... I replaced the CPS, new batteries, I am getting a litttle movement on the tach while its cranking. This all happened after I replaced the bad GPR. The old GPR was really shot with signs of arcing and sparking. My question is what would that have done?? Could I have friedd the IDM?? from the sparking?? or what else could that have srewed up? The truck had no problems until the GPR went bad. Thnaks for any help
 
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