At random my voltage gage will drop down to like 5 volts and stay there for a little bit then jump back to 14v, I thought the voltage regulator was going bad in the alternator so I bought a new one and it is doing the same thing. I cleaned all contacs and even ran a new wire from the alt to the battery direct then it stayed on 5v? This is driving me friggin nutz, at night my lights will dim a little and I can hear my blower motor slow down then when it jumps back up to 14v lights get a little brighter and blower motor starts going faster so there is some kind of draw but what?
Would a battery starting to go bad cause these problems? I put it on a meter and got 11.85v and 14.4 with alt running so I dont think the battery is bad. I could not get it to drop voltage when I had the meter on it, it just does it randomly!
mine did the same thing. but it was the alt. got 3 bad ones and the 4th was good.
Quote from: 82burban on November 29, 2011, 05:26:21 AM
mine did the same thing. but it was the alt. got 3 bad ones and the 4th was good.
I guess I will take it to autozone tomorrow and have them hook it up and load it and see if the alt is bad or the battery.
vehicle? unhook the power wire from the battery. if it dies, then its the alternator.
Maybe you have a bare wire somewhere grounding itself out
Sounds like something is turning on.... like ac compressor dropping the rpm. Heater on defrost kicks on the a/c compressor...
Only place to start is to replicate the problem... then start pulling relays. I say relays cuz that high of a load to dim the lights, definately draws some amps...
What vehicle is it?
Quote from: Eroq on November 30, 2011, 02:09:48 AM
What vehicle is it?
Its my 1991 gmc one wire alternator, it does it when the blower motor is not on also,I thought about the ac kicking on when the defrost is on also but thats not the issue. I took it to autozone this morning and they said my battery failed when they put a load on it, wondering if thats the issue or not? Going to get a new one friday anyway. I am also thinking wire grounding out somewhere...thats a huge posibility UGH!!! I dont think it is in any of my accessory circuits because it would pop a fuse, I am leaning towards bad connection on starter, ignition relay, ect so if new battery does not fix the problem we start chasing wires and connections I guess?
11.85 v is too low for a batt..
each cell generates 2.2v
you should have at least 12v disconnected and fully charged..
possible you have a bad cell or a short in the batt.
Quote from: Hammerlane on November 30, 2011, 05:33:36 PM
11.85 v is too low for a batt..
each cell generates 2.2v
you should have at least 12v disconnected and fully charged..
possible you have a bad cell or a short in the batt.
Thats what i was thinking too... bad cell
One thing you can do when you put the new battery in... turn everything off, disconnect the + on the batter and put an ammeter between the terminal and the cable, should have a super low reading around 1amp or so.... for the radio memory.
Quote from: J.C. on November 29, 2011, 12:09:08 PM
vehicle? unhook the power wire from the battery. if it dies, then its the alternator.
If your vehicle has an ECM (electronic control module, black box) this doesn't work anymore..
need to have at least 10v or something like that to it at all times.
that's an ole' skool trick.
Im thinkin if it is charging, then all thats left is bad battery, bad ground, or bad connection on the main power wire off the alt or terminal strip on the firewall. Sometimes they burn in 2 or get real corroded up there at the strip, behind the plastic cover with the plastic nuts on it by the heater n stuff. I did have one do wierd stuff like that and one day the alt fried and seized up, killed the motor in the middle of an intersection, but it had been showin good on the charge tests. It was on that truck on my pro pic.
Update, new battery, new alt, all new wires and the problem is gone except when I come to a stop, I think when I come to a sudden stop my rpm's drop and my alt does not spin fast enough.