Need some help solving electrical flickering

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Fuse boxes themselves are identified as I6 and V8. Nothing really regarding displacement and I can`t see what the difference could be.
 

Iron Indian

Member
Feb 13, 2018
26
Oklahoma City, Oklahoma
I’ve looked on TBSS owners and I come up with 25790682 for the fuse block. However when I check GM parts direct or other sites it says that PN doesn’t work for my truck. Anyone know by chance? This is for a 2007 Trailblazer SS 6.0
 

budwich

Member
Jun 16, 2013
2,027
kanata
iron indian... have you actually looked at the output of the alternator (ie. scoped) to see what it looks like? Further, have you looked at the control line? It might give you further clues as to what the issue might be... mechanical (alternator "body"), control glitch, or otherwise. If not, you might be wise to spend a few dollars on a "usb scope" or equivant (hand held scope) that will allow you to look at things.
 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I know you tried 2 different O'Reiley's alternators but for me, the biggest clue is that you tried a totally different one from another vehicle and it improved the flickering. I think it's possible that if O'Reiley's supplier is crap junk from China, you'll just get more of the same. Maybe try an ACDelco reman (although I had bad luck with one once out of the box). I know this is shotgunning it but we're down to this. If it was a wacky load from the truck, it would flicker with the alt wire disconnected.

This is getting a bit far fetched but what about making your own tester with a battery and load and see if it flickers on it's own. A scope would be ideal if possible but a fast reacting analog voltmeter would work.
 

Iron Indian

Member
Feb 13, 2018
26
Oklahoma City, Oklahoma
If you read the op of this thread he tried remans and a brand new OEM alternator with the same results. All my tests mirrior his. My results were about the same. If my truck alternator completely killed the flicker I would buy a brand new OEM, however this was not the case.

I’ve tested all the alternators I’ve put in by two different shops with the same results. Unless someone loans me an alternator or makes a bet with me so I don’t loose money when I get the same results, I’m not paying for another alternator on a guess that will likely be wrong and I’m out more money and nothing to show for.

Again start from the beginning of this thread and look what the original poster went through and see what I’m go through. It’s the same. If someone wants to put up there money for double or nothing let’s do it. Otherwise I need to move on. Ive put too much time and money on this alternator theory and I’m still at square one and no closer to a solution. Time to put this to bed and move on. Unless someone wants to make a wager? I can install a new alternator everyday and be $2,000 in the hole for nothing. I think it’s time to move on.
 

budwich

Member
Jun 16, 2013
2,027
kanata
:-( I guess you can call her "flicka"... :smile: Its too bad. Again, what testing was done? on vehicle, bench, with scope or just meter. A meter isn't likely to show you much. Anyways, with current technology, relative cheap test / metering can be had that could help.
 

budwich

Member
Jun 16, 2013
2,027
kanata
OK. thanks for the clarification. Although those are usually sufficient in most cases, it is likely that they aren't in this case. Anyways, its too bad that the issue is still unresolved as your vehicle deserves a better fate :smile:

Technology has moved in the diagnostic area of electronics such that relatively inexpensive scoping can be achieved either thru handheld standalone devices or with some computer addon usb interfaces that would allow you to look at things like ripple and overall wave forms along with control signals (PWM or otherwise). Further, since you have access to another platform that is working as expected, you don't really need to know the full details of the TB operational parameters, as you can just compare results between vehicles.

Anyways, it is what it is.
 

mntegra01

Member
Mar 26, 2018
86
Virginia
I’ve looked on TBSS owners and I come up with 25790682 for the fuse block. However when I check GM parts direct or other sites it says that PN doesn’t work for my truck. Anyone know by chance? This is for a 2007 Trailblazer SS 6.0

From my GM parts catalog PN s 25790682 no matter if its 2WD/AWD/5.3/6.0 same fuse box. Probably doesn't help to diag the issue tho. Can you DE-Pin one wire at a time at the alt plug and see if it changes on one wire at a time? I don't know if this would damage anything, need a schematic?

There should be a battery generator control module, does that test out good?
 

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wolfman 66

Member
Oct 14, 2013
2
Had the same problem replaced the battery control module. Flicker is gone part number for my 08 Envoy is 25864099
 

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