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Old 11-07-2004, 03:23 AM   #1
71Longbed
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electrical?

hello all having a littlebit of an electrical dilema truck starts up and runs fine the only thing is that when im driving it and come to a stop the lights and dash get dim and my sterreo shuts off and flickers someone told me it was a grounding problem current grounds i have put are to engine engine to chassay cab to chassy any help is appreciated also it only dims the lights when in drive
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Old 11-07-2004, 03:57 AM   #2
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might be a weak alternater.
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Old 11-07-2004, 06:39 AM   #3
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i thought it was too i replaced it and same old bull im gonna check the voltage tho
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Old 11-07-2004, 07:44 AM   #4
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I'm assuming your running a alt. with a external regulator, if so remove the cover off external regulator and take a emery file and clean the points, then while cover is off start motor and turn on headlights and such to see if points close, if they don't close then the electrical system is getting all its juice from the battery and none from alt. at idle, so then take a allen wrench and adjust points setting so they go closed at idle with headlights on this will then brighten your lights at idle.
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Old 11-08-2004, 02:33 AM   #5
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using internal regulated alter nator off of a 1986-7 silverado
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Old 11-08-2004, 04:55 AM   #6
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Did you run the brown wire to a gauge or light when you converted it to internal regulator alt? If not that might be the problem.And did you convert it using the layout in the FAQ,I did mine from there and it works perfectly.

http://207.44.196.117/vboard/showthread.php3?t=119379
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Old 11-08-2004, 05:15 AM   #7
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actually i didnt do this mod truk came that way when i got it im gonna check on it where should the brown wire be on my dash so i know
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Old 11-08-2004, 08:51 AM   #8
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Running about the same on mine, replaced alt and bat. About a week out the bat is so low, no good.

Keep us posted if you find out and I'll do the same.
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Old 11-08-2004, 05:16 PM   #9
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ttt
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Old 11-13-2004, 04:20 AM   #10
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k guys fixed up the problem now for the gentlemen that says he has the same prob i took it down to the ol electric shop of a freind so it didnt cost me a thing we found out the the little box on the fender with the lights and battery hook the connections were pretty dirty and tattered so we cleaned em up and threw on new connectors turns out i was losing 1 volt and a half after this simple fix i was all set no more dim lights Yippee!! hope this solves it for you aswell
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Old 11-13-2004, 04:44 AM   #11
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LOL so did your friend let you know when you were cleaning the terminals on the little black box that it was a external regulator for a externally regulated alternator. Any time you have dim headlights at idle the culprits almost always 99.9% of the time the external regulator for the alternator.
If your using a internally regulated alternator as you stated in earlier post off a late model truck you should not be using the external regulator at all, it should be by passed by connecting terminal #1 on plug for the external alternator to terminal #3, and connect terminal #2 to terminal #4, this effectively bypasses the regulator in the harness allowing you to use the internally regulated alternator. Without doing this you will experience the battery getting drained when truck off and sitting and other irritating electrical problems.
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Old 11-13-2004, 04:54 AM   #12
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im not sure were on the same page their paully my set up is internal regulated was done by an electronic sho i don't even have an external regulator in my truck where it use to be was on the radiator core support i trashed it during my engine reapainting session im talking about the little black box on the left fender my lights would only dim while idle in the drive position im unsure wut youre sayin but let me know im pretty sure the internal conversion is right 2 wires are joined and the harness for the external is just in the air since no external exist on my truck anymore
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Old 11-13-2004, 05:18 AM   #13
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What little black box on the drivers side fender are you referring to?? there isn't supposed to be anything between the alternator & battery in the wiring except a fusible link built into the charging wire and a junction block on passenger fender where charge wire connects from alternator & where charge wire to battery connects & if a gauge truck a wire for alt. gauge?? The externally regulated harness is the one thats supposed to have the jumpers on it from #1 to #3 terminal & #2 to #4. Its possible the electric shop disconnected external regulator and then ran all new wiring for the internal alternator instead of using what already existed by adding jumpers as I described.
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Old 11-13-2004, 08:22 AM   #14
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Thanks GMCPaul for that post, My 70 has been giving me headaches with drainage problems for some time.

Replaced alot of bad wiring, but still have the problem. This gives me one more thing to try. No one has ever mentioned that before. Or the box issue.
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