Chevy 350 Voltage Drop

AD43576

Member
Joined
Aug 31, 2011
Location
Hickory NC
I have an 88 Suburban and over the last couple of weeks I've noticed that while I'm idleing at stop lights I get a small voltage drop but it never goes below 13 during the day. Now at night, the problem gets worse with the lights, heater and radio running and it drops well below 13 but not into the red. I changed out the alternator (105 amp) today but it doesn't seem to have made a difference. I also had they battery tested and they said it was fine. What can I try next? Thanks in advance for any help.



Aaron
 
I would start with the easiest and simpliest and that's all the wire connections. One may be loose or a little crudded up. And you may have already done that.

Next while looking at the connections I'd see if any wires are properly grounded or be sure that none are worn in 2 from rubbing something.

Good luck man. I know electrical issues can be a big pain.
 
I just replaced my battery cables to 2 guage, both + and -. Do check your positive for wear, I had one wear through and almost burned up my truck. Even though they look good the connections to the ends can be bad.
Yep electrical issues are a pain.
Good luck
 
begin by checking your volt gauge.

Then, in addition to checking the engine & chassis grounds, alternator function and belt tension, check the battery condition and cable connections. Take a peek at the fusible links off the starter and firewall junction block. Check that all your connections are clean and tight and that none show signs of heat damage. You might also inspect the bulkhead connector through the firewall for heat stress. A poor connection anywhere (loose nut, poor wire crimp, weak terminal tension, etc.) in the 'feed' (high load) circuits will cause menacing loss of voltage. If the cause isn't readily apparent, you may need to perform some voltage drop tests across the harness. If your dash voltmeter is accurate, it sounds like you have more voltage loss than is typical or desirable. However, some voltage loss is normal and to be expected.... Good luck!
 
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also check your belts for wear. even though you may not hear them slipping or squeeling they may be slipping and causing your alternator to loose rpms which in return would cause the gauge to drop.
 
Thanks for all of the replies guys. I think I may start with a new belt and check all of my connections. Seems like the easiest things to do first. It may be the belt though because it's fine once you step on the gas and I do have a noisey belt, not sure which one it is though. Thanks again.



Aaron
 
A known issue on this vintage is the primary ground connection. Its a threaded tap not a nut on the vehicle side, they love to come loose over time and you get an iffy ground. Trace the neg cable from the battery back to first connection and see if you can wiggle it by hand.
 
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