elusive electrical issue, 95 tahoe

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Gemmell

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Hey there, I'll start off by saying that I've done a number of searches but haven't found my specific problem yet. But if I've overlooked it please send me that way. Thanks!

OK so my Tahoe has the voltmeter that dances with the blinkers and visually sees any draw on the system. Windows, locks, fan, lights etc. Definitely notice the drop in voltage when at a stop light. My sub at any decent volume will make it violently drop with dimming headlights and everything.

I've replaced the alternator, battery, ignition switch and added extra grounds to the frame, chassis and battery. All obvious connections are clean. Just not sure what I'm missing here. Wondering if there might be a power line grounding out somewhere.

It is worth noting that the oil Guage shakes most of the time, the fuel Guage dances with the sloshing of the fuel in the tank, and you can visually see when the thermostat opens up and closes on the temp guage. Ive read that the oil in the guage may be low??

Anyways, not sure where to go from here. Just looking to achieve a stronger and more stable electrical system. Thanks
 

drakon543

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Well if your running a sub on the stock lower outout alternator that could be an issue. The stock amp is 100, 105,120, 124 amp output. If you are using the 100 or 105 with an amplifier you could very well be torching the alternator pretty quick. Even at lower volume the amp is still drawing power. I suggest replacing the alternator with a higher amp one. Also if your using a regular cheap battery replace that with atleast a gold series or premium series battery from your local parts store. Lastly if your not using one get a cap for your amp it will reduce the punch it throws at your alternator and battery.
 
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Gemmell

Gemmell

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I've got an 8 farad capacitor in line. I read that you should have 1 farad per 1000 watts and I'm only running an 800 watt peak amp so I thought the strain would be pretty minimal.

These are definitely the right upgrades to make, I just find it so odd that comparable vehicles I've owned in the past (Chevy astro) with the exact same electronic components wouldn't see the same kind of draw when the blower motor is on.

When I replaced my alternator there was literally no change in performance from old to new which I found surprising. Even without the sub the electrical system should be able to run the blinkers or blower motor without dropping a volt or 2 on the meter.

I was kind of hoping that some cable is notorious for going bad but I suppose a better battery is a good place to start. Thanks!
 

drakon543

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Well you should be set with that cap inline as far as that goes. There are a few differences between the astro and a tahoe as far as electrical goes but they are fairly similar. One thing im assuming you replaced but i didnt see you mention. The power cables coming from the alternator and the power wire going to the main box. It is possible for corrosion to go up a wire before it starts eating away at it or having a small split somewhere that can go unnoticed and do the same thing. As far as the battery goes with an audio system think of it like the cap. A battery can only output a certain amount in a short burst as with the draw of an amp. A good cap helps but will never 100% solve a heavy draw. A cheaper battery has a lower burst output than a good battery. Speaking of the blower motor itself they can be known to have an excessive draw sometimes when they start going bad. Without the amp being powered at all yes the stock alternator regardless of ifs stock output will be able to power the vehicle without any issues. Unless with the vehicles factory systems its supposed to have the 120 amp and the parts store gave you the 100 amp. In that case with too many systems on you could see the same issue (without the amp).
 
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Gemmell

Gemmell

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OK thanks, I inspected the ends of those cables and they appeared to be ok so I never replaced them. I have read that replacing them solves similar problems so it's a good place to start.

Thanks!
 

drakon543

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Ya ive seen corrosion or specific fluids get on the power cables and it would actually work its way up the cable before stopping and festering in that spot. Without being there to inspect the situation first hand i just started off with any obvious possibilities with the information you gave in the first post. Either way tho if your running a sound system i would always suggest a higher quality battery than a basic one. Doesnt have to be a optima or anything crazy like that as your only running an 800w setup but just a premium series battery from your local parts store.
 
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Gemmell

Gemmell

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Yeah I'll definitely be upgrading my battery for sure. Unfortunately I replaced the main fuse box power cable and the alternator cable with no major changes, the gage still does its dance with the blinkers and other accessories. Even made sure the fuse box internals were clean. Not sure where to look next...
 

drakon543

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Hmm odd.
Far as im aware the voltage regulator is built into the alternator on these. The only other thing i can come up with is you have a bad circuit somewhere causing a voltage bleed when your using that circuit causing an excessive draw. Very rare problem ive only seen it once on a jeep.
 

JonnyTahoe

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Your temp gauge sounds like its working normal (should go up to about 210 and then drop down). As far as your fuel gauge mine will move around a lot too so this might be some what normal on these OLD trucks. When I'm low on fuel and come to a stop sign the gauge will go all the way up past full and then drop down. It has done this for the past Ten Years.
 

drakon543

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My 97 doesn't really do any of that :p. At 1/2 tank unless im accelerating like a drag racer or coming to a aggressive stop the fuel gauge doesn't move. At 1/4 it will move 1/8 on the gauge. The only time i see 210 is when im pulling alot of extra weight up a long hill. Regardless the only time ive seen the battery gauge fluctuate is a precursor to the vehicle leaving you stranded.
 

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