Voltage Guage Bouncing Around

[93RubyZ]

Hello. On my '93, the voltage reading bounces wildly around at idle or low speeds. When I'm at higher speeds, such as on the freeway, it does remain constant right around 13V. Is this the alternator that is getting ready to give out? I know the battery probably will need to be replaced eventually as it's been dead on a few occasions when it's not been driven for a few weeks. Although recently I've not driven it for a couple of weeks at a time and it's started right up. Any thoughts?

[Tom]

On my 90 the needle does move around more and reads lower at idle when the car has been running awhile and the battery is fully charged. The needle moves around less and stays at a higher reading if my car has been sitting a couple of weeks and the battery is slightly discharged.

Your battery might be OK since even a new battery will go dead if the car sits for a long period without disconnecting the battery. The owner's manual even has a statement to disconnect the battery if the car will sit over 25 days or the battery will go dead since there is a constant current draw to keep the computers going. The shop manual has a section that gives the current draw for various conditions ie; the car is shut off with the doors locked and the alarm engaged, the doors unlocked, etc.

There are three options to keep a good battery from going dead, drive the car every week or two, disconnect the battery if the car is going to sit, or use a battery float/maintenance type charger if the car is going to sit.

[Aurora40]

Anything happening when it does that? For example, mine wiggles up and down in tune with the turn signal when stopped. Not dramatically but it's easy to see the needle doing it.

[tomtom72]

Hey mine has been doing the same thing lately. Yes, my needle moves in time with the directional signals. It's been hot as hades here lately so I've been using the A/C alot. I notice a difference on the gauge with the A/C fan on different speeds also. I was gonna dig out my MT2500 scan tool and hook it up to see what the charging system is doing with the motor running.

I went out & bought a new battery yesterday just because the one in the car was there when I took delivery back in 12/04. The date code was never punched out so I don't know how old it is...except for the two yrs I've had the car & it's a no-name gas station brand.

I was thinking it was the heat wave we've had but I'm not positive so I'm gonna hook up and see if I can get a reading on alternator out put at least.

:cheers:
Tom

[93RubyZ]

Thanks for the replies. I'm starting to think the battery is fine as the last few times I've started it, it started right up even though I hadn't driven it in 2 or 3 weeks.

The guage doesn't seem to change if turn signals are on or anything else like that, at least not that I've noticed. I'll have to pay closer attention. The guage really just bounces say between 8 and about 15 volts and it does so just about as fast as this finger moves [-X . Reving the engine doesn't seem to have any affect on the guages, it still bounces around wildly, initially making me think the guage was broken.

The only time it doesn't seem to do this is at higher speeds such as on the freeway. Then it settles in around 13 volts and stays there. It's been hot here as well, but I'm pretty sure this was also happening earlier in the year when it was cold.

[Jason 91]

Have any of you noticed flickering brightness on the guages and interior lights in addition to this problem? I've noticed this recently on mine and I'm thinking it is the voltage regulator, but I'm really not sure. Any thoughts?

Thanks,

Jason

[93RubyZ]

Have any of you noticed flickering brightness on the guages and interior lights in addition to this problem? I've noticed this recently on mine and I'm thinking it is the voltage regulator, but I'm really not sure. Any thoughts?

Thanks,

Jason

Yes I have noticed that. I forgot to mention it. At high speeds (freeway type) that doesn't occur but the guage remains constant too.

[IowaZR-1]

hey gang!, I was getting the flickering dash lights and alternator was starting to make some noise but it spun free so I was going to rebuild it with bearings, brushes and new voltage reg(had read that an osolating reg would make the lights flicker)..took alternator apart and the stator was out of balance so I ended up getting one from O'Reilly with a lifetime warranty for just change over $100 exchange......volts run 14.2 @ 2000rpm in 5th gear now.. .the pulley was just a bit smaller which made getting the new gatorback belt on much eazier:)

[WB9MCW]

I would think it is the alternator going south and it is the regulator section. Try putting a external voltmeter on line and see if it reads the same as the dash one. This will at least confirm if the gage is an issue! I had this issue on a boat of mine and it turned out to be a bad multiplug connector (corrosion issue) that was the culprit. It took forever to pin it down after a new alternator did not fix it so it may not be the alternator but uaually it is. So a bench test of the alt at the parts store is a good idea (many can do this for you). Good luck let us know what you end up finding!

[tomtom72]

Not to beat a dead horse but this is what I observed after replacing my battery. I do not how old the former battery was because the date codes were not punched out and it was a "generic gas station" type but it had 700 amps.

I bought an autozone "gold series" by application and after trimming the area that holds the handle to the case it fit without affecting the gill panel fit & alignment. I'm gonna trim it more. Not a big deal but a minor pia, I guess I should have bought a GM/Delco battery...it proly fits better. That's the only negative comment I have for the A/Z brand so far.

On my gauge the readings don't move wildly or read consistantly low like before even as load varies and rpm varies after the initial recharge of starting usage. My old batt tested out at 12.2 volts after starting & running long enough to replace starting draw. The new batt was a bit low out of the box I thought, 12.5 volts. After runing the car the resting state voltage is 12.8...I guess that's okay. Anyway the net result seems to be that I have consistantly higher readings without the fluctuations. I figure my old battery was nearing the end of useful life even though it had over 12V at rest. I guess these cars have a prodigious power appitite?

:thumbsup:
Tom

[Jason 91]

I'm not sure if this is related or not, but I happened to notice around the same time the flickering lights started that my stereo stopped working. I didn't notice right away because I usually just listen to the sound of the engine :) The unit will turn on, but then it just turns off and on without playing any sound other than intermittently for a couple of seconds. I'd hate to think it's the unit...again. Does anyone have any thoughts on this?

Either way, I'm going to replace the alternator and hope that it solves this issue as well.

Thanks,

Jason