Voltage - The 1947 - Present Chevrolet & GMC Truck Message Board Network

pphatbasstard · 01-19-2003, 10:33 PM

I installed a volt meter in my truck and when I started it up it idled at 12v and if I rev the engine as high as it will go the volts will jump up to 14 for a long time and then it comes back down to 12 and then it dropped down to like 11 and some times regardless of if it is at 12 14 or 11 the needle will start jumping back and forth. I have a brand new alternator freshly tested battery and a voltage regulator that is less than a year old. Anyone every hear or seen this?

thanks guys

ChevLoRay · 01-19-2003, 10:40 PM

I already had a good alternator on it, and the battery was nearly new...the wiring harnesses (both engine and lighting) were replaced. Put new belts on the engine and whoa! Now the volt meter needle just sits there. No fluctuation. No nothing. So, what about your alternator belt? Is it loose? There shouldn't be but a slight amount of deflection when you press down on it between the alternator and the water pump. If it goes down as much as a half-inch, it is too loose. IF the back side of the belt has a smooth, shiny, glazed look, it could be slipping. Belt dressing may help, but be careful with it.

Gordo · 01-19-2003, 11:03 PM

Just a thought here, check your output with a hand held voltmeter, could be possible the gauge you have is ng.

pphatbasstard · 01-19-2003, 11:08 PM

belts r good and i have checked with a hand held meter the one in the cab is right on.

any other thoughts?

Longhorn Man · 01-20-2003, 01:45 AM

Check your ground.

pphatbasstard · 01-20-2003, 02:31 AM

battery has a new ground line.

I had a thought should the voltage reg. have anykind of rubber spacer inbetween it and the metal. People have told me for sometime that is should but mine never did and it always worked is that lack of a spacer catching up to it?

Blue_71 · 01-20-2003, 03:52 AM

i dont really know whats up with it but my volt meter in my 4x4 has started jumping, for some reason i can kick the fuse block and it will quit for a while and stay still

Fred T · 01-20-2003, 07:06 AM

Phat - Check your ground from the engine to the frame and body to the frame. Be sure the connections are clean. these trucks were lacking in the ground department. You can use a heavy test lead or jumper cable to check. Your regulator should have rubber washers built into the mounting holes that isolate the bolts and the base from the firewall.

Blue - Sounds like a bad connection in the plug on the fuseblock. You might take it apart and see if there is corrosion or evidence of arcing.

JimKshortstep4x4 · 01-20-2003, 08:47 AM

What you are describing indicates that there is a problem with your voltage regulator. If it has points, clean them and adjust your regulator. if it is solid state, then try another one on your
truck.

Jim

pphatbasstard · 01-20-2003, 11:27 PM

I got a new voltage reg. and it still dont work and if u dont have it grounded right to the metal it wont work at all. And the dude at auto zone told me that my truck should have any rubber between the regulator the truck.

sooo i still dont know whats up

red71cheyenne · 01-20-2003, 11:34 PM

Is this a stock voltmeter, or aftermarket? The stock voltmeter is actually an ammeter and is reading the output of the alternator to the battery. You should have rubber grommets in between the voltage regulator and the radiator support, but it shouldn't matter one way or the other. The v/r is still grounded via a strap to the radiator support. It almost sounds to me as if you either have a: an intermittent short to ground, or b: a bad voltage regulator. I don't think I helped any, but maybe its something else to look at. Good luck, Jeff.

Longhorn Man · 01-20-2003, 11:35 PM

I'm sorry, I ment the ground on your guage. Try grounding the inst panel or the volt guage at a minimum. If your lights aren't pulsating noticably, then I'll bet your charging OK.

01-19-2003, 10:33 PM	#1
pphatbasstard Registered User Join Date: Oct 2002 Posts: 166	Voltage I installed a volt meter in my truck and when I started it up it idled at 12v and if I rev the engine as high as it will go the volts will jump up to 14 for a long time and then it comes back down to 12 and then it dropped down to like 11 and some times regardless of if it is at 12 14 or 11 the needle will start jumping back and forth. I have a brand new alternator freshly tested battery and a voltage regulator that is less than a year old. Anyone every hear or seen this? thanks guys

01-19-2003, 10:40 PM	#2
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Yeah, my needle was jumpin' too... I already had a good alternator on it, and the battery was nearly new...the wiring harnesses (both engine and lighting) were replaced. Put new belts on the engine and whoa! Now the volt meter needle just sits there. No fluctuation. No nothing. So, what about your alternator belt? Is it loose? There shouldn't be but a slight amount of deflection when you press down on it between the alternator and the water pump. If it goes down as much as a half-inch, it is too loose. IF the back side of the belt has a smooth, shiny, glazed look, it could be slipping. Belt dressing may help, but be careful with it. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

01-19-2003, 11:03 PM	#3
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Just a thought here, check your output with a hand held voltmeter, could be possible the gauge you have is ng. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

01-20-2003, 07:06 AM	#8
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Phat - Check your ground from the engine to the frame and body to the frame. Be sure the connections are clean. these trucks were lacking in the ground department. You can use a heavy test lead or jumper cable to check. Your regulator should have rubber washers built into the mounting holes that isolate the bolts and the base from the firewall. Blue - Sounds like a bad connection in the plug on the fuseblock. You might take it apart and see if there is corrosion or evidence of arcing. __________________ Fred There is no such thing as too much cam...just not enough engine.

01-20-2003, 11:34 PM	#11
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	Is this a stock voltmeter, or aftermarket? The stock voltmeter is actually an ammeter and is reading the output of the alternator to the battery. You should have rubber grommets in between the voltage regulator and the radiator support, but it shouldn't matter one way or the other. The v/r is still grounded via a strap to the radiator support. It almost sounds to me as if you either have a: an intermittent short to ground, or b: a bad voltage regulator. I don't think I helped any, but maybe its something else to look at. Good luck, Jeff. __________________ 1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty

01-19-2003, 11:08 PM	#4
pphatbasstard Registered User Join Date: Oct 2002 Posts: 166	belts r good and i have checked with a hand held meter the one in the cab is right on. any other thoughts?

01-20-2003, 01:45 AM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Check your ground.

01-20-2003, 02:31 AM	#6
pphatbasstard Registered User Join Date: Oct 2002 Posts: 166	battery has a new ground line. I had a thought should the voltage reg. have anykind of rubber spacer inbetween it and the metal. People have told me for sometime that is should but mine never did and it always worked is that lack of a spacer catching up to it?

01-20-2003, 08:47 AM	#9
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	What you are describing indicates that there is a problem with your voltage regulator. If it has points, clean them and adjust your regulator. if it is solid state, then try another one on your truck. Jim

01-20-2003, 11:27 PM	#10
pphatbasstard Registered User Join Date: Oct 2002 Posts: 166	I got a new voltage reg. and it still dont work and if u dont have it grounded right to the metal it wont work at all. And the dude at auto zone told me that my truck should have any rubber between the regulator the truck. sooo i still dont know whats up

01-20-2003, 11:35 PM	#12
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I'm sorry, I ment the ground on your guage. Try grounding the inst panel or the volt guage at a minimum. If your lights aren't pulsating noticably, then I'll bet your charging OK.



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