Fixing Low Voltage Problem on OBS Chevy Truck
In this episode we tackle the common low voltage problem with the OBS (Old Body Style) Chevy Truck or "GMT400" charging system. Mine is a 1988 GMC K1500 single cab short bed with a 383 stroker and a Holley Sniper EFI. We use a multimeter to find some high resistance wires and bypass them with a new piece of battery cable and get the system charging at 14 volts.
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Great video I had to do the same thing with sky-high wire Mechman alternator and a AGM Odyssey Battery🇺🇲
Good video, thank you for showing that crimping tool I've never seen 1 before.
@kellybuilt1
Жыл бұрын
No problem 👍
You just showed me what I need to do on my '89 F150. Thank you.
@kellybuilt1
Жыл бұрын
Cool! Let us know how it goes!
Thank you so much I took care of the problem. The problem was on the left side of the passenger engine bay wall with the harness goes into the computer in the glove compartment looks like a scrap rat chopped away on them in the winter while I used to turn on the truck in my carport due to gravel as well. Gave me a lot of surface. Rust oxide wires, but sniffed everything away. Cleaned everything up fired right up with no problem. Thank you so much. I really appreciate you getting back to me you’re the best.
@kellybuilt1
Жыл бұрын
Right on! I'm glad you figured out the problem!
Wow this worked for my truck - good Job
@kellybuilt1
Жыл бұрын
Great to hear!
I always wire brush the bolt holes on the alternator and the bracket. Take the battery leads apart and sand then down. It made my starter a lot faster.
I went threw today and checked, and removed the main old grounds in the engine bay of my 88, and the one on the filler neck. They were old and tattered and needed replaced.
Im going to try 4awg wire. Using the lights and AC blower will cause my system to drain power, eventually causing dash warning lights. EVEN though my Powermaster Alternator is keeping up. So OBVIOUSLY a wire issue. the factory wire off the ALT is so small. Ty for this video.
@davidhay1303
6 ай бұрын
This
Had the same issue but was just a bad connection at the back of the alternator
Don't forget your ground cables.
Has something to do with the charge light my charger is giving the battery 14.6 volts but the brown wire from the dash charge light puts out 12.6 volts.
On the 2 Guage were is the usable link?
For me it was the battery to alternator sh$t wire. It was way undersized from the factory
I'm having the same charging problem on my 96 k1500 Did your alternator pully get hot when it was running low voltage. I change the idler pully and belt and alternator. Still runs 10 amps
@joshua12345j
Жыл бұрын
10 volts I mean
@kellybuilt1
Жыл бұрын
No the pully didn't get hot that I know of. I replaced the alternator a while back because it started growling and making noises. I think the bearings or whatever the shaft rides on failed.
OK so just so I understand this… Originally you had a positive cable running down to the starter and now you took that battery cable out and ran one from the alternator directly to the battery… And from the battery you have a cable going down to the starter. Is that correct?
@kellybuilt1
6 ай бұрын
Hey, sorry if it was confusing. I didn't remove the positive cable running from the battery to the starter. I didn't even remove the original wire from the the back of the alternator. I just added another cable to the post on the alternator, in addition to the stock one, and ran it straight to the battery positive. Basically creating a parallel path to the battery. Not exactly 100% the best way to handle it. But it works to bypass any factory wiring that has high resistance. If that makes any sense..
How are you doing? I have a 91 GMC sierra CK 1500 anyway I am having a problem maybe you can help me I change distributor cap rotor wires plugs Marjo heat sensor sending unit sensor fuel filter, alternator battery, grounded, everything in the engine bay like you could never imagine swapped out alternator wire to to gauge from positive to the alternator. Also change the coil. Hi change everything you could imagine even the bar on the firewall to the passenger side that distributes the current throughout the whole engine, be spotless clean, the right amount of voltage, my hood light works fine my winding light on the fender passenger side works fine and I am still having the check gauge light on and the battery light on I can put the key in fuel pump runs like a baby car will crank all day long will not crank over now. I have no idea maybe being where I’m keeping it at in a carport sitting on top of gravel where they were the dirt ones, I don’t know if that has anything to do with it but before the lights were coming on the truck was turning on and backfiring that issue has stopped. The truck has been running fine parked it didn’t turn it on for a couple days and when I go to turn it on nothing but problems mind you he has a brand new battery as well. Can you help me thank you my name is Wilfredo.
@kellybuilt1
Жыл бұрын
Sorry, Wilfredo. I don't think this video will help you with your problem. Sounds like it might be something outside of the charging system.
Have never had any charging issues like that with any of my obs's . The problem i have encountered every time is those crappy side post battery clamps.
@kellybuilt1
Жыл бұрын
Yeah I prefer the top post clamps too. They seem to clamp a lot better but I never got around to converting these.
You must replace the battery charger with one more ampere; Because this is not enough and it will crash
So the existing alternator wire is discontinued?
@kellybuilt1
Жыл бұрын
No the factory one is still there too. Just added another one.
@DiegoLopez-ii7ve
3 ай бұрын
Im changing that wire, do i need fuse to a 2-4 gauge from the alt to the batt?
Change that alternator n battery
Did you ever figure out the problem
@kellybuilt1
Жыл бұрын
Yes. High resistance in the stock wiring.
@mrworldwide6770
Жыл бұрын
@@kellybuilt1 thank you for getting back with me and I found out mine was bad grounds and a bad alternator
@kellybuilt1
Жыл бұрын
Bad grounds will get you.. My ignition box and my front clip wiring were sharing a bad ground a while back and the engine would shut off every time I turned on the right turn signal... It seemed too strange to be true until I fixed the ground!
@criscastro60
5 ай бұрын
thanks for the video- on my 91 gmc c1500 the wire on the back of the alternator does not go to the battery, it goes to the junction bar inside the engine bay on the passenger side- is that normal?
@criscastro60
5 ай бұрын
if i put a new wire from alternator to battery can I keep the existing one that goes to the junction block or do i need to remove it?