Voltmeter is in the red zone

82 GT · 10-08-2004, 02:35 PM

My factory voltmeter in my '88GT is reading in the red zone.
Does this mean the alternator is bad since my battery is only a few months old?

mustangman65_79 · 10-08-2004, 02:58 PM

usally yes.

Is the car running?

GhettoPop · 10-08-2004, 03:12 PM

Quote:

Originally posted by 82 GT
My factory voltmeter in my '88GT is reading in the red zone.
Does this mean the alternator is bad since my battery is only a few months old?

take a multimeter to the battery. with car running it should read at least 13.5V or more, probally 14V, anything under 13V is bad news. do it now, cuz a bad alt will kill your battery in no time. a bad alt can sometimes be spotted by dimming headlights, dimming cluster, gauges going crazy, stereo problems, etc.

with the engine off, i think the batt should measure around 12.5V.

i picked up a 130amp from PaPerformance, lifetime warranty and charges great even w/ underdrive pullies, less whine too.

82 GT · 10-08-2004, 06:58 PM

Quote:

Originally posted by mustangman65_79
usally yes.

Is the car running?

Yes, that's with the car running. Earlier tonight, when I was driving it, I noticed it was a notch below mid-point of the gauge then it went down to just above the red zone.
I'm going to have to get another battery/alt. tester cause I can't find mine.

Ieatcamaros · 10-09-2004, 04:48 PM

Yeah, if it's got a bad diode it will drain your battery. Just check it with a multimeter, you don't have to have a special battery alt. tester.

XBAJBUSX · 10-12-2004, 01:41 PM

it else could be the regular 2 .

Falcons Talon · 10-12-2004, 02:03 PM

Old trick here.

With the car running, disconnect one of the terminals from the battery. If it dies, its the alternator.

GhettoPop · 10-12-2004, 03:55 PM

Quote:

Originally posted by Falcons Talon
Old trick here.

With the car running, disconnect one of the terminals from the battery. If it dies, its the alternator.

Never heard this one, that will show if the alt is not outputting power. But can your test show if the alt is outputting less than it should be?

Falcons Talon · 10-12-2004, 04:02 PM

Nope. I just yank it off and take it to the local auto zone for that. Since I went with the 130 alt swap over a year ago, I haven't had a problem w/ battery or alternater. Not bad for a $30 junkyard alternator. I still remember the words out of the mouth of the Autozone tech I was talkiing to about the swap. He said "See you in a couple of weeks" This was over a year ago.

red82gt · 10-12-2004, 04:36 PM

With the stock alternator, you'll probably have just over 13 volts at idle, at around 1500rpms, it should be over 14V. Another possibility is that the gauge has gone south.

10-08-2004, 02:35 PM	#1
82 GT Import Slayer Join Date: May 1999 Posts: 2,241	Voltmeter is in the red zone My factory voltmeter in my '88GT is reading in the red zone. Does this mean the alternator is bad since my battery is only a few months old? __________________ '82 GT 351W (.060)Comp Cams 274* Extreme Energy cam, ported & polished heads w/ 1.94/1.60 valves 10.3:1 flat top pistons,stealth intake, Mallory dizzy,Holley 750dp carb, BBK shorties,Flowmaster exhaust,C-4 with 3700 stall converter, B&M pro shifter,8.8 rear, 4:10's, subframes, electric fan, powermaster alternator, 4 core radiator.

10-08-2004, 02:58 PM	#2
mustangman65_79 My poor 79 RIP Join Date: Oct 2001 Location: Suisun City, Posts: 2,320	usally yes. Is the car running? __________________ '84 mustang GT turbo '85 LTD '89 Camaro Irocz z28 '94 Lightning '96 Trans am

10-09-2004, 04:48 PM	#5
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Yeah, if it's got a bad diode it will drain your battery. Just check it with a multimeter, you don't have to have a special battery alt. tester. __________________ The sig says it all.

10-12-2004, 02:03 PM	#7
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Old trick here. With the car running, disconnect one of the terminals from the battery. If it dies, its the alternator. __________________

10-12-2004, 04:02 PM	#9
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Nope. I just yank it off and take it to the local auto zone for that. Since I went with the 130 alt swap over a year ago, I haven't had a problem w/ battery or alternater. Not bad for a $30 junkyard alternator. I still remember the words out of the mouth of the Autozone tech I was talkiing to about the swap. He said "See you in a couple of weeks" This was over a year ago. __________________

10-12-2004, 01:41 PM	#6
XBAJBUSX Registered Member Join Date: Oct 2004 Location: NEW JERSEY Posts: 41	it else could be the regular 2 .

10-12-2004, 04:36 PM	#10
red82gt Sober voice of Reason Join Date: Nov 1998 Location: Kelowna, B.C., Canada Posts: 1,514	With the stock alternator, you'll probably have just over 13 volts at idle, at around 1500rpms, it should be over 14V. Another possibility is that the gauge has gone south. __________________ 393W: AFR 205's, hydraulic roller, TKO600.

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