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I did the Alt mod, the ACD DR44G (334-2529A), on my bird. The BATT gauge has always flopped around, I figured it was doing its shitty GM gauge dance, but it usually held at the tick after 13; however, just recently, it's been holding below 13. Also, when it surges to the tick past 13, the lights dim and you can hear the loss in power (notice my RPM, OP gauges, and when the battery gauge moves).
I had the charging system tested, at Advance Auto, and everything came back good. I don't get it. I hate dealing with electrical issues 😖
Any ideas?
BTW, how the hell do you read these gauges? What are the values between the ticks?
* I got the battery and alt back in 3/2020, so no warranty on the Alt
* Alt is an AC DELCO unit
* 02 Trans Am stock, with Sony HU and half *** working OEM speakers
Voltmeter jumping could be for many reasons. First thing I would do is measure voltage across battery at same time and see what it is and if it is fluctuating too. If not, then you know it's just some little glitch more local to the voltmeter.
The voltmeter in the gauge cluster shares B+ with all the other gauges and light bulbs (from the 10A Gauges fuse). It could be one of the other gauges misbehaving that's causing it to jump around. Or it could be the gauge itself, or maybe a loosening connection. It shares ground with some of the gauges and some of the light bulbs, and is grounded at the left kick panel. I would check if the ground it clean and tight. Maybe pull the dash and make sure the terminals on the gauge are in good condition, etc, etc.
Voltmeter jumping could be for many reasons. First thing I would do is measure voltage across battery at same time and see what it is and if it is fluctuating too. If not, then you know it's just some little glitch more local to the voltmeter.
The voltmeter in the gauge cluster shares B+ with all the other gauges and light bulbs (from the 10A Gauges fuse). It could be one of the other gauges misbehaving that's causing it to jump around. Or it could be the gauge itself, or maybe a loosening connection. It shares ground with some of the gauges and some of the light bulbs, and is grounded at the left kick panel. I would check if the ground it clean and tight. Maybe pull the dash and make sure the terminals on the gauge are in good condition, etc, etc.
But it's not just a malfunctioning gauge, the surging is legitimate, not a gauge only issue. Every time it surges, I hear and feel it in the RPMs, all the lights dim (head lights, gauge, etc,), the engine loses power, etc.. Sometimes it makes the engine stutter so much, I think it will stall out. All this actual power surging just recently started. I hope I'm explaining that good enough to make coherent sense, lol...
But it's not just a malfunctioning gauge, the surging is legitimate, not a gauge only issue. Every time it surges, I hear and feel it in the RPMs, all the lights dim (head lights, gauge, etc,), the engine loses power, etc.. Sometimes it makes the engine stutter so much, I think it will stall out. All this actual power surging just recently started. I hope I'm explaining that good enough to make coherent sense, lol...
FWIW - At ~166,000 miles, my 99T/A started doing basically the same things shortly after the 416 install. At idle, gauge surged, dash and headlights would yo-yo with the gauge surge. It gradually got worse and more prone to surge.
Short version, shop said the voltage regulator in alternator was on the way out. They replaced the alternator and issue disappeared.
Whatever course you take if replacing alternator comes up, if possible I'd have the trusty local mom & pop's shop repair your current alternator and go through it. Probably cost less than a $100 and you'll know exactly what you're getting. Saying that because nearly all the remanufactured alternators & starters these days from auto parts retailers seem sketchy in my experience...assuming the retailer can even order the correct part.
Most common issue with remans,,, cheap rectifier assemblies.. There are specialty outfits that build heavy setups for ambulances and police cars etc that fit in the stock housing OR can be mounted externally if you need big power..
You can also with some research remove the sides from the holder and order them via electronic suppliers, like Mouser
I just looked at videos on a larger computer screen. First video seems the alternator is randomly overcharging (high voltage). Second video seems the alternator is actually turning off / on and overcharging at times too. Fuel delivery will change with voltage so engine ECM might be having a bit of a tough time adjusting fueling to the quick voltage swings that are out of range of normal operation.
I would put a voltmeter on the battery posts and see if it's doing same thing there (probably is). It would actually be more ideal to measure at alternator but that's a little dicey knowing where the alternator is located. Basically you've got to figure out if this is a charging system issue or if it's a power distribution issue further down the harness. Seeing it overcharge makes me think it's an alternator regulator issue as someone said earlier. But good to have real measurements to witness that before pulling parts so your remove & repair time is worthwhile.
I have a similar issue just show up like this a few days ago. I borrowed the battery from my 99 Silverado because my Suburban's battery died. When I reinstalled it a week later, I noticed the speedometer was pegged at maximum inside and engine surging intermittently, sometimes enough to stall the engine. The cluster voltage also surges and and I had a DVOM handy and was showing fluctuations. When voltage dropped to around 6-7VDC engine stalled. This truck is not a daily and I haven't driven it, but it was fine prior to swapping the battery. Maybe during swap something got fried? I do have a spare alternator to swap to see if problem goes away. The speedo pegged is probably another problem?
FWIW - At ~166,000 miles, my 99T/A started doing basically the same things shortly after the 416 install. At idle, gauge surged, dash and headlights would yo-yo with the gauge surge. It gradually got worse and more prone to surge.
Short version, shop said the voltage regulator in alternator was on the way out. They replaced the alternator and issue disappeared.
Whatever course you take if replacing alternator comes up, if possible I'd have the trusty local mom & pop's shop repair your current alternator and go through it. Probably cost less than a $100 and you'll know exactly what you're getting. Saying that because nearly all the remanufactured alternators & starters these days from auto parts retailers seem sketchy in my experience...assuming the retailer can even order the correct part.
I talked to a rebulider in Ohio (alternatorstarterrebuildkits.com) and they said that the VR doesn't cause these kind of issues, with a DR44G, and that it sounds like it could be the diodes and would do a full rebuild for $100, but my problem is, this is my DD, so having it down for a week would be hard.
Most common issue with remans,,, cheap rectifier assemblies.. There are specialty outfits that build heavy setups for ambulances and police cars etc that fit in the stock housing OR can be mounted externally if you need big power..
You can also with some research remove the sides from the holder and order them via electronic suppliers, like Mouser
I was in an accident and have nerve damage in my hands and arms, so unfortunately I can't do a lot of my own work.
Do you know any specific shops, that have a good rep, who builds the heavy setups?
I talked to a rebulider in Ohio (alternatorstarterrebuildkits.com) and they said that the VR doesn't cause these kind of issues, with a DR44G, and that it sounds like it could be the diodes and would do a full rebuild for $100, but my problem is, this is my DD, so having it down for a week would be hard.
I talked to a rebulider in Ohio (alternatorstarterrebuildkits.com) and they said that the VR doesn't cause these kind of issues, with a DR44G, and that it sounds like it could be the diodes and would do a full rebuild for $100, but my problem is, this is my DD, so having it down for a week would be hard.
Yes, can see where with the DD, it's way harder to do the pull & repair.
Makes sense, they just told me something or other to cover the electronics. Probably was a diode and not the VR.
I just looked at videos on a larger computer screen. First video seems the alternator is randomly overcharging (high voltage). Second video seems the alternator is actually turning off / on and overcharging at times too. Fuel delivery will change with voltage so engine ECM might be having a bit of a tough time adjusting fueling to the quick voltage swings that are out of range of normal operation.
I would put a voltmeter on the battery posts and see if it's doing same thing there (probably is). It would actually be more ideal to measure at alternator but that's a little dicey knowing where the alternator is located. Basically you've got to figure out if this is a charging system issue or if it's a power distribution issue further down the harness. Seeing it overcharge makes me think it's an alternator regulator issue as someone said earlier. But good to have real measurements to witness that before pulling parts so your remove & repair time is worthwhile.
So the tests that Advance Auto weren't the right tests?
I have a similar issue just show up like this a few days ago. I borrowed the battery from my 99 Silverado because my Suburban's battery died. When I reinstalled it a week later, I noticed the speedometer was pegged at maximum inside and engine surging intermittently, sometimes enough to stall the engine. The cluster voltage also surges and and I had a DVOM handy and was showing fluctuations. When voltage dropped to around 6-7VDC engine stalled. This truck is not a daily and I haven't driven it, but it was fine prior to swapping the battery. Maybe during swap something got fried? I do have a spare alternator to swap to see if problem goes away. The speedo pegged is probably another problem?
WOW, that's crazy! My Batt gauge always flopped around, intermittently, but nothing surged, so I figured it was the typical gauge BS, these cars have, but now this surging came out of the blue and the batt gauge is acting even crazier now.
Yes, can see where with the DD, it's way harder to do the pull & repair.
Makes sense, they just told me something or other to cover the electronics. Probably was a diode and not the VR.
Did you do the Alt mod too? From what I got from my conversation with the rebuilder, the issue of it possibly being the diodes and not the VR was a DR44G thing. Something to do with the way that unit was designed, so maybe your issue was the VR, unless you have the DR44G too.
I can't say, I don't know what kind of tests they run. If it's in car then it's probably not much of a test.
Did you see the pics I posted, in the OP, of the Advance Auto test? I'm sure it's not the most comprehensive test, lol, but I figured that it would shed some light on the issue, but then everything came back GOOD, so who the hell knows.
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Alt, Batt, Surging issues - 02 Trans Am 
