Charging issues
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5th Wheeling
Joined: Jul 2017
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Charging issues
Batteries were suddenly stone dead one morning, swapped them out for some fresh interstates. Fried the injector harness, went to pull it back into garage to get working on it, batteries were dead again. Fixed the truck, new alternator, good to go. Drove the truck around for about a week and a half, voltage gauge on cluster was reading low, no battery light. Got system tested at autozone, drove back home swapped the alternators and the batteries were dead again. I charged them up , started the truck ran it on high idle for 10 or 15 minutes and it died again, stone cold dead. New alternatir was reading low again while idling. I am completely lost here. Tight connections grounds seem to be in ok shape, any help on this issue would be greatly appreciated, thanks
Lead Driver
Joined: Apr 2016
Posts: 7,171
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From: Bahstun
Start with this and also get a new pig tail for the alt
https://www.ford-trucks.com/forums/1...ou-cranky.html
https://www.ford-trucks.com/forums/1...ou-cranky.html
Postmaster
Joined: Sep 2007
Posts: 4,195
Likes: 6
From: Medford Oregon
Sounds like a shorted (internally) GPR. If so there would be a very large current draw on the batteries all the time and the alternator would never keep up (charge). One big post on the relay should be hot all the time and the other big post (2 wires) would be hot for up to 2 minutes after starting (cold) then the relay should de energize. Usually much less time that that depending on temperature.
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5th Wheeling
Joined: Jul 2017
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Swapped out new pigtails, cleaned terminals VERY well, charged up batteries all day on 2amp trickle charger, both read good, and disconnected glow plug relay. Fired truck up and still not reading low on gauge with the battery light on now. I have no idea what to do now
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5th Wheeling
Joined: Jul 2017
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Also just performed a battery and alternator test on my truck via my craftsman scanner plugged into my obd2 port. Batteries read low, which may be because they are not fully charged. Alternator read low output at somewhere in the high 11’s like 11.49 or 11.94 dont remember which sorry. Any other ideas? Going to leave the truck on trickle charge overnight (hopefully not a few days) to keep them fresh
Hotshot
Joined: Dec 2012
Posts: 11,266
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From: Las Cruces New Mexico
Use a test light and see if you have current on both big terminals of the GPR with key off, if you do the GPR is shorted there should be only one terminal with constant 12v. When batteries on these trucks die quick its a sure sign the GPR is shorting out.
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Lead Driver
Joined: Apr 2016
Posts: 7,171
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From: Bahstun
Also just performed a battery and alternator test on my truck via my craftsman scanner plugged into my obd2 port. Batteries read low, which may be because they are not fully charged. Alternator read low output at somewhere in the high 11’s like 11.49 or 11.94 dont remember which sorry. Any other ideas? Going to leave the truck on trickle charge overnight (hopefully not a few days) to keep them fresh
If the GP relay was shorted out. Your Alt might have over heated. If you have 12 going in on pigtail and nothing but battery volts on output then Alt would have to be bad.
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5th Wheeling
Joined: Jul 2017
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That is no Alt output. You are reading battery. Should see at least 13 volts. The pig tail, does it have power to it? have an ohm meter? please ohm out the cable from alt to battery to see if there is an open.
If the GP relay was shorted out. Your Alt might have over heated. If you have 12 going in on pigtail and nothing but battery volts on output then Alt would have to be bad.
If the GP relay was shorted out. Your Alt might have over heated. If you have 12 going in on pigtail and nothing but battery volts on output then Alt would have to be bad.
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5th Wheeling
Joined: Jul 2017
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That is no Alt output. You are reading battery. Should see at least 13 volts. The pig tail, does it have power to it? have an ohm meter? please ohm out the cable from alt to battery to see if there is an open.
If the GP relay was shorted out. Your Alt might have over heated. If you have 12 going in on pigtail and nothing but battery volts on output then Alt would have to be bad.
If the GP relay was shorted out. Your Alt might have over heated. If you have 12 going in on pigtail and nothing but battery volts on output then Alt would have to be bad.
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5th Wheeling
Joined: Jul 2017
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ok so i tested the relay, key off both sides were hot so it is shorted. was actually smoking a little bit and burnt my finger when i touched it, so that seems to be a little off lol. Tested the batteries, had exactly 12v on both. Tested the pig tail, had 12v on that as well. with the output post DISCONNECTED from the battery and with the motor running, it was only reading about 2 volts. With it connected i got a perfect 12 so i would assume that is because it was coming from the battery. So to confirm, this means i should go swap the alternator and GPR and I should be good to go?
🧐
Lead Driver
Joined: Apr 2016
Posts: 7,171
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From: Bahstun
GP shorts out and draws high amps and welds the contacts of GPR and then over works the charging system
I think your alt is bad by the test you did. Volts is not going up when you have 12 on exciter.
Your GPR is bad from welded contacts.
Unplug the GP that's burt out. It can run fine with a few GPs out. Just smoky and rough till it warms up.
You need GPR, get a stancor one
new GPs only get ZD11 motor craft ones
UVCH can get oem pieces or upgrade to SD ones which can carry more current with out burning out.
I think your alt is bad by the test you did. Volts is not going up when you have 12 on exciter.
Your GPR is bad from welded contacts.
Unplug the GP that's burt out. It can run fine with a few GPs out. Just smoky and rough till it warms up.
You need GPR, get a stancor one
new GPs only get ZD11 motor craft ones
UVCH can get oem pieces or upgrade to SD ones which can carry more current with out burning out.