High Voltage Surge

[CFR__AND_SONS]

What could cause a sudden spike in voltage? And what damage can that cause?

This might not have anything to do with it but this had never happened until they swapped out the ABS relay valve... I had a voltage spike yesterday. It was raising past 15.5 v so I pulled over and turned off the truck. When i got back on the road, it was running good. Mine runs at like 14.8 all the time. But later on in the day it was going past 15v so i was getting the buzzer and volt light on. So I would just turn on the AC full blast to bring it down. Any ideas?

[Unilevers]

voltage reg in the alternator? bad batteries? bad battery connections? excessive current draw? bad gauge in the dash?

one of those is your issue. verify the voltage with a multimeter at the batteries. i would also do a load test on the batteries them selves and load test the alternator output.

[CFR__AND_SONS]

Thank you. I will check those as soon as I get to work today.

[Waterloo]

That is how my alternator acts when she is going bad, spikes, drops, runs normal, spikes drops and then fails... On my second one since owning the truck. The reman Delco I had on just gave up the ghost, just out of warranty too... Imagine that? I put a new one on, no more remans, and working fine.

[CFR__AND_SONS]

I believe the one on this truck is new. I'll have to check.

So what kind of damage can the high voltage do?

[Waterloo]

(09-21-2016 )CFR__AND_SONS Wrote:  I believe the one on this truck is new. I'll have to check.

So what kind of damage can the high voltage do?

Mine was pegging out when she went the first time, I honestly did not experience any damage that I know of, and that was over two years ago. BUT! I did find that my factory cabling was garbage! Bare cable everywhere, from the factory, I replaced nearly 100 feet of OEM copper cabling with new stuff, all of the power and grounds was replaced. I could not believe that this truck rolled off of the line the way it did. Honestly, I was lucky the truck did not catch fire, it was that bad.

So check your cabling, get under the truck and LOOK! The cable to my starter had 10" of bare exposed copper, no jacket whatsoever. It was green from end to end, around 15+ feet of 0 gauge cable. The grounds were the same, all green and oxidized, you could break the wire with your fingernail, it just disintegrated when you touched it. I have no idea how the truck started, or even ran. I have never seen anything like it.

Anyhow... When this latest Alternator went, I did not give it a chance to go as far as the last one did, and I got it off of there ASAP. New one is working fine, and I went to the dealer and bought the OEM alternator that was meant for the truck, a Leece-Neville. It was the same cost as a new Delco, and is correct one for my truck. Not that another Delco would not have worked, it would have. But my luck with non OEM parts has not been the greatest as of late, so I went to the dealer this time around.

[CFR__AND_SONS]

(09-21-2016 )Unilevers Wrote:  voltage reg in the alternator? bad batteries? bad battery connections? excessive current draw? bad gauge in the dash?

one of those is your issue. verify the voltage with a multimeter at the batteries. i would also do a load test on the batteries them selves and load test the alternator output.

My batteries are new and the reading is correct 14.5. Same with the alternator.

Could the spike be cause by a short? It was raining yesterday...

[Waterloo]

Get under the truck and check your cabling and wiring, especially where any exits the sleeper and along the frame rails. Secure anything you find lose or rubbing after inspecting. Also open the battery box and check to insure the connections are tight on the posts, and that all are connected as they are supposed to be, take your time and really look, I have missed connecting this one wire I have at times when working on the truck. Check your grounds, especially at the engine block, you should have one at your starter, you will need a flashlight. If you see any exposed cable, I would replace it, odds are it is green and not doing its job.

Then, it might be a good idea to look in the fuse panel, check the fuses for any signs of trouble, like scorching or melting. If you have a Prostar, there are fuses and relays under the hood and in the driverside sleeper compartment. Check those too.

Under the hood, look at the connections on your alternator, make sure nothing is rubbing or is exposed to the elements, a nicked wire, or connections are lose. I routinely check my wiring, from the firewall to the CAC. I like to use that liquid electrical tape if I find anything that has rubbed or any suspicious connectors and seal it from the elements. The stuff is fantastic, and can be used in a pinch. https://www.amazon.com/Permatex-85120-Li...rical+tape

If you find any wires or cables rubbing against something, you can either zip tie and secure them, or if you are not able to do that, wrap the cable or wire in some old heater hose and secure the hose around the cable or wiring with zip ties. This will protect the wiring or cable and let that old heater hose take the abuse. Just remember to secure it, and check periodically. Or, use this wire loom protector, I buy it in 100 foot boxes in various sizes... I was just under the truck and used about two feet of this and resecured a cable just yesterday. https://www.amazon.com/Support-Split-Fle...+protector

At the rear of the tractor, check your lighting connections. I just recently had to rewire my entire ass end. I had repaired it before from the previous owner, but it was to the point it was giving me issues elsewhere in the truck. I bought a Weatherpack connection kit from my local Car Quest Auto Parts store, here is the same kit http://www.jegs.com/p/JEGS-Performance-P...5/10002/-1

The OEM harness connections were shot, so I cut them off and installed the Weatherpacks, along with a new back up alarm. One thing I like to use too, is dialectic grease, you can get it in most auto parts stores. It is weather and waterproof. I like to get the large tube and keep it in a zip lock bag. Here is the stuff I use, great for outdoor satellite installs too... https://www.amazon.com/Dielectric-Waterp...ric+grease

Also, the dialectic grease, I like to use it on my battery connections, the posts, smear it on there, not to heavy, but enough to cover the nuts. It eliminates the corrosion at the posts, and is cheap insurance. And when splicing wires, if you do not solder and use but connectors, I use the grease or silicone caulk in the connection ends, insert wire and crimp, then use the shrink tube over that to seal from the elements.

Another thing, and this has been discussed numerous times here... It is a good idea to replace your fuses, as they lose their effectiveness over time. They do not blow, they just lose their mojo, especially these cheap Chinese ones. I have some of the mini fuses that I have to replace every few months, especially the one for my AC blower motor. These are the Mini ATM fuses, in 5A, 10A and 30A. I am also replacing all of the OEM resettable fuses, will pick them up tomorrow from the dealer... Having electrical issues myself... Narrowed it down to the fuses, I am replacing all, including the relays.

I just bought a box of each of these, Bussmann, better quality and a good price on Amazon...

https://www.amazon.com/gp/product/B004AH...UTF8&psc=1

https://www.amazon.com/gp/product/B004AH...UTF8&psc=1

https://www.amazon.com/gp/product/B009WQ...UTF8&psc=1

I hope this helps you. This is pretty much what I do when I believe I have electrical issues. So far so good, and I have not had to visit any mechanics for anything more than to slap their computer on my truck to tell me where to look, or what module to replace. Then I go home and fix the problem myself, to know it is done right and to inspect for other issues near the problem... They usually come in threes on my truck.

Good luck!

[CFR__AND_SONS]

I'm curious to know what your trucks voltage reading is at idle speed with no load on the alternator. I feel 14.5 is a bit high. I have interstate acid filled batteries.