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My 84 Suburban saga continues

RNation

RNation

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St.Peters, MO
Just when I thought I had all the bugs worked, I forgot about the electrical part...haha.

My problem started the other day when I noticed the alternator gauge was showing very low voltage. I checked and the alt belt was broke off laying in the side by the wheel well. So I put the spare belt on, fired her up and noticed the alt gauge was showing it was over charging over 18volts (past the red line, it almost seemed like the only reason it wouldn't go any farther is because the gauge wouldn't let it).

So I shut the truck off when I got to my destination (about 5min after I noticed the over chargining), then when I went to turn the truck back on I got nothing, no power to anything, dash, winshield wipers, power locks, etc.

I thought it might have something to do with the starter solenoid so I had it checked at oreillys, it was bad so I got another starter and alternator. Put them both on and still had the same problem, no power. My friend jumped the post on the glow plug relay while I turn the key over and voila it started. So I bought a new one but still had the same problem, no power. Also when we started it the volt meter was over 18volts again (even with new alternator)

That's where I'm at now. We checked all the fuses we could think of also inline fuses and all were well.

I was under the impression that the voltage regulator was built in the alternator, so if that's so what else could cause the high voltage charge. Also I thought maybe the gauge was faulty but I noticed the windows went up and down probably twice as fast, so it seemed like the gauge is correct.

So me and my friend are stumped. Any ideas?
 
Sounds like the fusible link. BTW the factory belt for the alt suck. It should be a 7x Gates. Get the HI per belt. It is a gates 5725 IIRC. I have explained the problem many times in other posts. It has to do with worn pulleys and the discontinuation of the proper thickness belt. A 7x series belt will not last 3 months normally unless your pulleys are like brand new and even then I have seen them fail prematurley.
 
We checked the fusible links, we found 3, but they looked alright. Is it possible for those to go bad and still look ok? And could that cause the alt to overcharge?
 
Looked ok ??
Test each side with a test light. Also check the wire going from the alt to the batt. If the alt is not making connecting to the batt it will be all over the place. Check for power at the lug on the firewall. Should be about center IIRC. Just sold mine so can't go look and my CUCV is totally different.
 
The fusible links looked good, just 26 years old.

Ok I will try those spots.

The wires that leave the alt don't go directly to the battery though, do I follow them till they end and check them the whole way?

And I forgot to mention that when we jumped the posts together on the glow solenoid and the truck started, we then had power to the windows, locks, wipers, etc.
 
I ampretty sure one of the wires off the alt goes to the batt. I remember tracing it on my 90 Burb when i couldn't get the truck to shut off . It's not the ones that plug in on the top, it's the one that goes on the pos nut on the back IIRC.
 
I found the culprit, ther'e 2 wires coming from the starter solenoid to a "junction post" on my firewall. The 2 wires go through a plastic piece (i think is a fusible link) and come out with 1 wire. The single wire was burnt out pretty bad. The alternators back at 12v and I have power again when I turn the key on.

I don't however have a wire that goes directly from my alt to the battery. The wires come out of the alt and run into the other mess of wires around the back of the motor then they disappear into a 4th dimension I guess...haha
 
It goes into the group of wires that go around the back of the motor, I'll have to check tommorrow when I got some light to see where it goes from there.
 
probably goes to the starter. thats how the older gms I've worked on were. kinda used the starter for a junction block
 
When the sense wire to the alternator opens up or can't see the output voltage the alternator can go full voltage. There are two wires on the plug, one to the ignition/alt lamp and the other to the main junction. The main purpose is to compensate for voltage drop due to load on the wire. You can bypass it and take the 'reading' off the charging terminal.

This wire not getting voltage is why your voltage reading went through the roof.

Fusable links break from stress and age. They may look good and be open.
 
Ya, 1 went to starter other 1 went to junction post on firewall, and the last 1 (brown wire not red) goes to the fuse box.
 
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