Catastrophic Electrical Problem - will it ever end?

[gavio]

So I replaced my alternator 'cuz the voltage regulator in my old one had gone bad and since it was old anyway, I figured I might as well just get the whole rebuilt deal. The one I got is a higher output rebuild from alterstart in Texas.

Seems OK, though I noticed two things different: one is that the voltage seems to fluctuate more than it used to, but since it didn't go over 14 volts I didn't stress about it too much, and the other is that the engine sort of vibrates in a grumbling kind of way in spurts when it is idling.

Today, I have a monster head-cold/flu thing going and I just have one thing to accomplish and so I'm driving along and I'm thinking "Wow, my van is running REALLY well today" and I get on the freeway to come home and go to bed and I'm doing 75 in the left lane and I start smelling a burnt smell and I see that suddenly the voltage has popped off the scale (way past 18) and I immediately head for the shoulder and the door locks start cycling and the windsheild wipers start goin' crazy (of course it's raining). I get pulled over and shut down pronto noticing that the violtage dropped in the seconds that the engine was just idling. I get out and poke around a bit to make sure nothing's on fire and everything seems perfectly normal and quiet. I go in to try the key and it's dead - no glows, no starter, no gauges, no wipers, no nothing. Curiously, the stereo and parking lights still work, but nothing else at all.

So while I'm sitting there in the rain blowin' my nose and waitin' for the towtruck, I get to thinkin' "What the heck happened here?" I assume everything's dead because the excess voltage blew all the fuses.

But what about the voltage regulator? Did I just get unlucky and my new alternator had a bad regulator too, or is something else causing the regulators to get fried?

If anybody has had the patience to read this all and has some insight, I'd appreciate it. Since it's still raining and I still have a cold, I'm not into going out there now, but I'll have to get it fixed soon.

Thanks for reading.

[britannic]

Hope you get well soon and it's not the 'flu you have :( .

Sorry to say, but you've got the same problem, the alternator's overcharging again.

There may be something that's causing the regulator to fail, such as a bad ground to the alternator or on the block.

Another cause can be the power wire to the alternator, if the regulator doesn't get a feed it can allow the alternator to overcharge.

Check all of your ground and 12v connections when you can and take the alternator to a shop that can test it to rule it out of the equation.

[ 12-12-2003, 06:42 PM: Message edited by: britannic ]

[crew84]

My first problem I had with my truck was electrical. In 1988 I decided to do some preventative maintenance to my starter. I found that the starter support bracket was missing and bought another. I also bought new bushings, brushes, and solenoid for it since the truck had over 100,000 miles on it. This was my first diesel starter I had worked on. It was a little heavier and awkward to pull out. I replaced the parts and I was surprised about the bushing wear which meant I replaced them in time. It was hard to put it back in place with the heat shield but I got it done.
It started great and I was happy. I drove it about ten miles the next day and IT HAPPEN!!
The smell of wire burning and the battery gauge pegging. I pulled over and shut it off. I tried to start it and nothing...no battery power. I had it towed home and searched down the problem. I had sandwiched the main two 12V power wires' fusible links that connected to the solenoid's battery terminal against the heat shield and exhaust manifold. This started a chain of events that lasted for a long time. The short ruined the links. I soldered in two replacements. I found out later that this caused more problems. I started to have voltage problems when it charged. Some days it charged fine and other days low. I went through the charging system replacing parts and then the belt. To shorten the story was that I had to replace the wires that I had used to replace the links with ones that were not altered. It seems that it had gotten hot enough to cause resistance to current flow. I suppose that the end connectors had burned enough to cause it. After the replacement my battery gauge works right. I have looked at many wire harnesses on 6.2L trucks at our U-Pull-It wrecker and have seen many of them burned at the starter. That is a place to start if you can not find anything obvious.

[catmandoo]

on my olds with the 5.7s that was a very typical problem but on those after putting the starter in and the shield which took houdini to get in there and ya hook the batteries up and hit the key and "pop" blow both fusible link wires, after doing that a couple of times decided no more pulled the wires up on top and ran new fusible link wires right to the battery cured that problem plus less wires down under.all you need down there is the battery cable and the big purple wire

[DYNA]

Man this is great! Just reading about somebody else's problem I've fixed mine! For years my Blazer has had minor gremlins in the electrical system,slow power windows ,fluctuating gauge readings,etc. Well i used the fuse link idea to the batteries.Wow what a difference. Thanks men I Love the Diesel Page!!! Dwayne

[gavio]

Well, I did a little preliminary poking around today (not quite well enough to get really into it, yet) and found some new info. First is that the red fusible link wires do not run down to the starter - all that's down there already are the purple and the power cable. I confirmed this with my wiring diagrams which show that the vans are different than the CK trucks - who knows why....

However, there are two fusible link wires which come off the junction block and dissapear into the wiring harness. One of those is burned completely through and the other is visibly toasted.

According to my wiring diagram, one connects to the alternator charging wire and the other to the small red wire in the alternator plug. Both of them also connect to the block which feeds the rest of the body (no doubt explaining why everything's dead).

Questions are first, what do you use to replace these - is there a suitable item available at the parts store or what?

And second - now what? How do I figure out what caused this? Is the fusible link going south the cause of the overcharging I saw or is it the result? The alternator is a PITA to remove (it's a van, remember) so I'd like to have some idea what's going on, if possible before resorting to that.

Any more thoughts?

[Larry Andrews]

One thing I learned long ago with an old Triumph Spitfire...auto electrical specialists usually don't care much which car they're working on. Wires are wires. So don't feel weird about taking your diesel to one, it's what they do. They're also usually much cheaper!

I understand exactly what Gavio is going through. (I too have the an 83 G20 and also this stupid flu) Fortunately, someone else got stuck replacing the fusible links in my van as they've obviously been replaced. But it's definitely a pain to track down where wires go in the harness and the logic of why things are routed the way they are is a challenging mystery. (still looking for a *good* wiring diagram for the van, BTW)

Anyway, the links in my van have a plastic connector that clips onto the base wire. No heat is involved so no damage to old insulation. Have no idea where to get them though.

One thing that will definitely cause the fusible links to pop is connections that are corroding and acting as resistors. Effectively dropping line voltage, the corrosion will cause ohm's law to kick in and raise current flow to get adequate power for device operation. High current flow equals blown fusible links, voltage is irrelevant.

[gavio]

Yeah, the wiring diagrams I have are certainly a challenge - the information is there, but it takes hours of staring at them to understand, and even then...

Say, does anyone know at what current flow those links are supposed to pop? That might be a clue...

[Eric Deslauriers]

Originally posted by gavio:

However, there are two fusible link wires which come off the junction block and dissapear into the wiring harness. One of those is burned completely through and the other is visibly toasted.

According to my wiring diagram, one connects to the alternator charging wire and the other to the small red wire in the alternator plug. Both of them also connect to the block which feeds the rest of the body (no doubt explaining why everything's dead).

Questions are first, what do you use to replace these - is there a suitable item available at the parts store or what?

And second - now what? How do I figure out what caused this? Is the fusible link going south the cause of the overcharging I saw or is it the result? The alternator is a PITA to remove (it's a van, remember) so I'd like to have some idea what's going on, if possible before resorting to that.

Any more thoughts? Gavio,

Good parts stores can sell you fusible links in rolls. I have some that I used to rewire one of my vehicles. It says "Fusible Link" right on the insulation. BE SURE you have what you think you have.

Sounds like the alternator is toast and severely overcharging. Dollars to donuts it's a reman. Two things I hate in this world - reman carbs and reman alternators. They both suck beyond belief.

The only remans I've ever had any luck with (either carb or alt) are the ones I've rebuilt.

Your alt will put out the most amps around 1500-2000 rpm, prolly what you were running down the road.

Get it checked, if it's trashed, ding the reman company for the $$ caused by their reman (it can be done, just painful), and get a NEW alternator. Not a reman, a NEW unit. They're worth the $$$ if you don't have your original to rebuild.

Make sure they test the diode plates.

To get it checked, you could disconnect it, make sure your batts are charged, and drive to somewhere that can check it in the vehicle. Hook it back up, check it, then decide what to do.

Good luck