Jumping volt meter
Thread Starter
Racer
Joined: Sep 2015
Posts: 250
Likes: 29
Jumping volt meter
Not sure if this is anything to worry about or just one of those annoyances that i'll be living with. I noticed this week that my volt meter will jump occasionally (like every 20-30 seconds). It typically stays around 13 volts but will drop and go back to the same output, very quickly. My battery is staying charged and it doesn't make any difference if the lights are on, or any other electrical draw.
Is this something to be concerned about ?
Is this something to be concerned about ?
Racer
Joined: Nov 2011
Posts: 285
Likes: 36
From: Cedar Park TX
Unfortunately you may have to look at the gauge itself.
One test that my help, if you can recreate the issue with the car idling in the driveway, hook a voltmeter up to the battery and see if that jumps too. If not, the gauge may have an issue.
One test that my help, if you can recreate the issue with the car idling in the driveway, hook a voltmeter up to the battery and see if that jumps too. If not, the gauge may have an issue.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
OP, when you say you checked bat wiring....did you go under the bat compartment to the frame under there, and clean/shiny metal/steel and bright metal from the negative to the frame there, and secure with a good solid bolt?? and then on the right side from the engine to up/under the engine mount horn from the frame?? do the same.....
Then, clean them sanitary from any and ALL grease/oil, and use RTV black to cover the connection but GOOD.....preclude any corrosion/rust bad connections on down the road.....
Then, clean them sanitary from any and ALL grease/oil, and use RTV black to cover the connection but GOOD.....preclude any corrosion/rust bad connections on down the road.....
Burning Brakes
Joined: Jan 2012
Posts: 943
Likes: 73
Not sure if this is anything to worry about or just one of those annoyances that i'll be living with. I noticed this week that my volt meter will jump occasionally (like every 20-30 seconds). It typically stays around 13 volts but will drop and go back to the same output, very quickly. My battery is staying charged and it doesn't make any difference if the lights are on, or any other electrical draw.
Is this something to be concerned about ?
Is this something to be concerned about ?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Either the voltage regulator is going out in your alternator, there is some problem with wiring, or the gauge connections are loose/defective. Easiest way to determine which is to put a multimeter on DC Volts setting and wire it up to the battery connections and compare readings between car gauge and meter. Also, connect multi-meter to alternator output then drive and compare gauge and meter.
The results of those tests will tell you what direction to go to resolve your problem.
The results of those tests will tell you what direction to go to resolve your problem.
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Burning Brakes
Joined: Sep 2005
Posts: 1,050
Likes: 205
From: Lewes Delaware
Either the voltage regulator is going out in your alternator, there is some problem with wiring, or the gauge connections are loose/defective. Easiest way to determine which is to put a multimeter on DC Volts setting and wire it up to the battery connections and compare readings between car gauge and meter. Also, connect multi-meter to alternator output then drive and compare gauge and meter.
The results of those tests will tell you what direction to go to resolve your problem.
The results of those tests will tell you what direction to go to resolve your problem.
I had the same problem on my 73 (amp meter) and it turned out to be both issues described by 7T1vette. Rebuilt the alternator (NAPA kit replacing the voltage regulator) and cleaned/tightened the contacts on the alternator and the wires attaching to it via the black plug. Problem solved.
Fran
Last edited by Blue73Shark; Oct 28, 2017 at 07:51 AM. Reason: Add amp meter
Burning Brakes
Joined: Oct 2013
Posts: 1,114
Likes: 520
From: McClellandtown, Pa.
I also agree with Fran and 7T1 in that you should check the alternator wiring and voltage regulator. When my voltage meter went bad my volt meter started to jump and also my interior lights flickered with the gauge. A simple quick test to check if it is the voltage regulator is to just unplug the plastic wire connection on the top of the alternator and see if the pulsating meter and interior lights stop, if so, it's the voltage regulator which is located inside the alternator. Here's what they look like.
Hope this helps,
Tooch
PS- Don't drive the car with that unplugged! It's just a quick test that my mechanic told me about...
Hope this helps,
Tooch
PS- Don't drive the car with that unplugged! It's just a quick test that my mechanic told me about...
Last edited by Tooch1; Oct 28, 2017 at 09:10 AM.
Pro
Joined: Nov 2016
Posts: 729
Likes: 118
From: Kelowna British Columbia
Put a meter across battery terminals and when the voltmeter does this look at meter and see if it mimics? May need some jumpers to get it on seat where you can see it. It should be an analog meter. Does tapping the voltmeter cause this? as connection could be loose on back.