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electrical charging problem 77 eleganza [message #308867] Mon, 17 October 2016 08:49 Go to previous message
lqqkatjon is currently offline  lqqkatjon   United States
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
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Ok, I helped a friend get into GMC's, and I understood from the start, that I may have inherited a second GMC to keep running, but the good thing is I do not have to pay any of my own money on it.

My problem is trying to balance time between work, family, my own projects, ect.. ect... So I was hoping to get some advice to maybe give me a starting point when I go over and try to figure out the elecrical problem his GMC has now developed.


We had the battery isolator bad on our trip back home, So when it got back, we replaced the battery cables, isolator, boost solenoid, had the alternator rebuilt. (rebuilder said it looked good-but changed the brushes). I also had him install a PD converter and sent the buzz box over to my ham radio friend.

for the most part the 77 eleganza 2 looks original, but someone had cut and rewired all the wires to the fuse panel. They looked to do a good job for the most part, heat shrinking connections, and keeping all the same wire colors. so basically the harness is all the same, but the last 6-8" of wire going into the fuse block is replaced. It does look like he kept it all original though.


I had everything working as I thought it should when I sent him home with it. All 3 posts of the isolator were properly putting out 14+volts, and it seemed good.

Now it quit charging. and further diagnosis, we seem to not have dash lights now, and the fuse seemes burnt for the dash lights.(the one tiny fuse...what is with that pain!). But now I do not even have 12V power on either side of that fuse holder in the fuse box. I tried changing the fuse, and even jumped 12v to the fuse spot, and did not seem to fix the dash lights.

What also is going on, is with engine running (I am guessing with ignition on... not necessary engine running I forgot to check and am now just gathering my thoughts). is there is the coach and engine batteries are connected(with house battery disconnected, we are getting power to the house side. when I had it running). Boost solenoid is new and working correctly.

I am also getting 10v off the center post to alternator.


I am guessing I am having a "sense" wire problem to the alternator. Plus something is shorted or wired wrong in the dash connecting the ignition feed to something on the house side. thinking back, this could of been a problem all along, but i do not think so, because originally when the isolator was failed on the drive home, we were not getting battery power from the coach battery over to the engine battery without engaging the boost solenoid.



So any help where to start looking to where the ignition wire might be crossed or shorting over to the coach side. Also is there a easy way to wire the voltage sensing wire over to the alternator as a temp fix? I am trying to talk him into camping this weekend with me, so I have all weekend to work on it at the campground. but need to get charging situation fixed to run the lights because it gets dark so early. otherwise I do not have much time before then.

FYI- there is no APC cable. he ordered one over the weekend and hopefully may have it this week to install.


thanks for all help. I am guessing it is going to take opening up the dash and hunting up what is going on with the dash lights. I am also trying to figure out where the orange wire that is connected to the boost solenoid that goes into the fuse panel, but bypasses the actual fuses and goes up into the dash is for. Someone thought radio, but??



Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/

[Updated on: Mon, 17 October 2016 08:52]

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