Amp gauge going crazy...help. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

skydiver · 05-02-2009, 08:53 PM

Ok. This one is stumping me. When I start the truck the amp meter in the dash is stable and everything is fine. But when I turn on the turn signal, or hit the brakes, or anything else that draws a current, the needle on the amp meter starts bouncing from one stop to the other (waving at me). I have checked for continuity in the wires and all seems fine. The only thing I noticed is that the voltage out of the alternator fluctuates by 2V when the blinker is on. The alternator has been rebuilt. Does anyone have any experience with this? Any suggestions where I should look next?

skydiver

Wrenchbender Ret · 05-03-2009, 10:37 AM

Sounds like a bad ground. Make sure you have a good heavy ground connection from the engine to the frame & the frame to the body. Check the connections at the junction block.

cdowns · 05-03-2009, 11:48 AM

the way to check a grond is to take it apart clean both sides to shiny metal and put back together// looking at it does nothing

skydiver · 05-04-2009, 05:30 PM

Thanks for the tip. I will check all grounding points.

skydiver · 05-04-2009, 08:07 PM

Just checked and cleaned the grounding at the engine and the body. Still have the problem. Wondering if it could be a bad battery now. Or bad alternator. Just had the alternator rebuilt last year and had them add a few more amps of power. Wondering if it is too much now. In a nutshell, amp gauge is bouncing back and forth and the headlights (when on) vary in intensity. Also, I think I am over charging the battery b/c when I kill the engine the battery is whistling (de-gassing?).

I am so not an electrical guy

. Need some expert advice on this one. Has anyone had this problem before?

Bears63 · 05-05-2009, 01:08 PM

I have seen this happen when voltage regulators go bad. Have you checked that?

**VetteVet** · 05-05-2009, 02:50 PM

I suspect you have a voltage regulator problem as well and have you checked the water level in the battery? If you have been overcharging all this time you may have boiled some water out of it and that would cause the fluctuations. How much voltage are you reading at idle at the battery with no loads on the system. It helps to know if you have the external regulator or the one inside the alternator .

skydiver · 05-05-2009, 07:52 PM

I have an external voltage regulator and have replaced it already. Didnt stop the problem. The voltage I am reading at the battery with no load is about 13.7 volts. The voltage out of the alternator is about 14 but fluctuates from 13 to 15. I have a feeling that its the alternator. I had it rebuilt by a local shop and at the same time they bumped up the amps to about 75 from 60. Does anyone know if the output from the alternator is to be steady or varying?

Sinister · 05-05-2009, 08:22 PM

Just put a new internally regulated alternator in my truck and the output varys.

05-02-2009, 08:53 PM	#1
skydiver Just a fan. Join Date: Dec 2007 Location: Royal Oak, MI Posts: 39	Amp gauge going crazy...help. Ok. This one is stumping me. When I start the truck the amp meter in the dash is stable and everything is fine. But when I turn on the turn signal, or hit the brakes, or anything else that draws a current, the needle on the amp meter starts bouncing from one stop to the other (waving at me). I have checked for continuity in the wires and all seems fine. The only thing I noticed is that the voltage out of the alternator fluctuates by 2V when the blinker is on. The alternator has been rebuilt. Does anyone have any experience with this? Any suggestions where I should look next? skydiver __________________ skydiver 1972 C10 Medium Bronze

05-03-2009, 10:37 AM	#2
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: Amp gauge going crazy...help. Sounds like a bad ground. Make sure you have a good heavy ground connection from the engine to the frame & the frame to the body. Check the connections at the junction block.

05-03-2009, 11:48 AM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Amp gauge going crazy...help. the way to check a grond is to take it apart clean both sides to shiny metal and put back together// looking at it does nothing __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

05-04-2009, 05:30 PM	#4
skydiver Just a fan. Join Date: Dec 2007 Location: Royal Oak, MI Posts: 39	Re: Amp gauge going crazy...help. Thanks for the tip. I will check all grounding points. __________________ skydiver 1972 C10 Medium Bronze

05-04-2009, 08:07 PM	#5
skydiver Just a fan. Join Date: Dec 2007 Location: Royal Oak, MI Posts: 39	Re: Amp gauge going crazy...help. Just checked and cleaned the grounding at the engine and the body. Still have the problem. Wondering if it could be a bad battery now. Or bad alternator. Just had the alternator rebuilt last year and had them add a few more amps of power. Wondering if it is too much now. In a nutshell, amp gauge is bouncing back and forth and the headlights (when on) vary in intensity. Also, I think I am over charging the battery b/c when I kill the engine the battery is whistling (de-gassing?). I am so not an electrical guy . Need some expert advice on this one. Has anyone had this problem before? __________________ skydiver 1972 C10 Medium Bronze

05-05-2009, 01:08 PM	#6
Bears63 ...just another truck junkie.. Join Date: May 2009 Location: Watertown, SD Posts: 698	Re: Amp gauge going crazy...help. I have seen this happen when voltage regulators go bad. Have you checked that? __________________ Mike "Bear" Shea

05-05-2009, 02:50 PM	#7
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,719	Re: Amp gauge going crazy...help. I suspect you have a voltage regulator problem as well and have you checked the water level in the battery? If you have been overcharging all this time you may have boiled some water out of it and that would cause the fluctuations. How much voltage are you reading at idle at the battery with no loads on the system. It helps to know if you have the external regulator or the one inside the alternator . __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

05-05-2009, 07:52 PM	#8
skydiver Just a fan. Join Date: Dec 2007 Location: Royal Oak, MI Posts: 39	Re: Amp gauge going crazy...help. I have an external voltage regulator and have replaced it already. Didnt stop the problem. The voltage I am reading at the battery with no load is about 13.7 volts. The voltage out of the alternator is about 14 but fluctuates from 13 to 15. I have a feeling that its the alternator. I had it rebuilt by a local shop and at the same time they bumped up the amps to about 75 from 60. Does anyone know if the output from the alternator is to be steady or varying? __________________ skydiver 1972 C10 Medium Bronze

05-05-2009, 08:22 PM	#9
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: Amp gauge going crazy...help. Just put a new internally regulated alternator in my truck and the output varys. __________________ Beat it to fit, Paint it to match... Last edited by Sinister; 05-05-2009 at 08:22 PM.



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