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Discussion Starter #1
Had some strange things happen today and need some help figuring it out.
turned traction control off to do a burnout and throttled the engine in park to clear it out. Traction control came back on. At the same time the abs light and srs light blinked on the dash and the headlights either dim or shut off when stabbing the throttle hard.
need some guidance on where to go. Car won’t shift right at wot and pops and bangs while it does shift.
any help is appreciated.
 

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If a ground, G102 on Rt side frame rail in eng. compt. supplies grounds for headlamps and abs module,remove it,clean frame and terminal side of wire and add shake proof washer under terminal to frame,try that first
 

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Discussion Starter #3
Thanks for replying. Checked that ground along with the other 2 in the engine compartment and the one near the battery. Still no luck. Could it be a bad alternator?
 

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If the Alternator was real bad, I'm pretty sure you would get a prominet DIC display telling you so. Probably the battery icon as well. You could get into the engineering page prior to or during an engine start/run cycle. Then scroll down to the voltage page. Then you could monitor the output of your Alternator while trying various driving technique's. In itself, it doesn't solve your problem, but it would/should verify IF that Alternator might be part of it.
 

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Discussion Starter #5
An additional note to add. During all of this craziness, the tach doesn’t follow the engine speed. I can clear it out (say 6k or so) and the tach will jump to 4K and kind of hang there. It does eventually drop back to idle but is slow to respond either up or down. I did check engineering mode today and in accessory position it shows battery voltage as 11.7 and battery charge at 43.1%. While running voltage is 14.7 and charge is the same. I’ve heard of some type of setting that has to do with charging speed or capacity monitoring but I have no experience with that part.
 

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Discussion Starter #6
Does the alternator on the G8 have an internal voltage regulator? Is it possible for it to fail without causing issues during normal driving? It seems it only pops up under heavy load of any type, wot in gear or hard revving in park or neutral.
 

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Check this...https://www.g8board.com/threads/battery-ground-bolt-read-and-check-yours.224746/ along with the battery connections (both post) in the trunk.
 

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The alternator has an internal voltage regulator.
 

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Discussion Starter #9
I have checked that bolt as well. I have not removed it but all seems good.
 

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  1. you can verify those grounds by taking a voltage drop test from the engine block to the cable leads, with dig, voltmeter put black meter wire on good ground and red one on ground cable,turn everything on a/c, lamps etc and make sure no more than 0,5 V difference ground to ground,pay carefull atention to crank pulley for slippage or no more than 4mm wobble,the regulator is actually in the ecm,regulates from the battery sensor at batt ground cable via data from bcm
 

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Discussion Starter #11
Do you think this is a ground issue or component issue?
 

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A few years ago, a member had all kinds of weird things happening to his car. It turned out to be caused by his underhood fuse panel. There are "2" hex screws that secure the "3" wire loom connectors to the bottom side of that fuse panel. He found that the screws were loose, which caused several circuits to intermittently stop performing correctly. Could it be (since you had major engine rework done on your car), that your underhoood fuse panel was disturbed during the rework ? Easy enough to check an verify using either a 10mm socket/ratchet combo or correctly sized philips screwdriver. .
 

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Discussion Starter #13
Thanks for replying. It has been almost 5 years since the engine mods were done but I guess I can’t rule anything out. It seems to be load related. Normal street driving it’s fine other then the lights dimming. When at the track or driving aggressively the harder you lean on it these things pop up. I don’t drive it much at night but noticed the lights dimming last month. Tracked the car Saturday and all of the other items popped up. Hard raps on the throttle will reproduce it all. Steadily increasing rpms in park or neutral and nothing.
 

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Discussion Starter #14
I believe I found these two screws. They are inside of the fuse box under the lid. They don’t come out but they also don’t tighten snugly. You can see them draw up or release the copper part of the connector as you turn clockwise.
I have checked every ground possible except for the one in the rear package tray.
 

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The alternator has an internal voltage regulator.
Had some strange things happen today and need some help figuring it out.
turned traction control off to do a burnout and throttled the engine in park to clear it out. Traction control came back on. At the same time the abs light and srs light blinked on the dash and the headlights either dim or shut off when stabbing the throttle hard.
need some guidance on where to go. Car won’t shift right at wot and pops and bangs while it does shift.
any help is appreciated.
Had some strange things happen today and need some help figuring it out.
turned traction control off to do a burnout and throttled the engine in park to clear it out. Traction control came back on. At the same time the abs light and srs light blinked on the dash and the headlights either dim or shut off when stabbing the throttle hard.
need some guidance on where to go. Car won’t shift right at wot and pops and bangs while it does shift.
any help is appreciated.
Had some strange things happen today and need some help figuring it out.
turned traction control off to do a burnout and throttled the engine in park to clear it out. Traction control came back on. At the same time the abs light and srs light blinked on the dash and the headlights either dim or shut off when stabbing the throttle hard.
need some guidance on where to go. Car won’t shift right at wot and pops and bangs while it does shift.
any help is appreciated.
Had a similar issue on my GT that at WOT run all the electronics would shut off, under normal driving it was fine. After lots of sleepless nights pouring over it, it ended up being the alternator, it was a reman, replaced it with a OEM one and it's been working perfect since.
 

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Discussion Starter #16
That was my thought too. Literally just got done replacing it with a PPV GM alternator about 10 minutes ago. Same issues still there.
 

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Best bet is to see if abs/traction codes are in history and go from there,and scan a snapshot of data while it happens otherwise you will be changing parts galore
 

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Discussion Starter #18
No codes present in the system at all. After doing some digging, I am leaning towards a bad bcm. I had removed the trunk light to replace a bulb and the metal tab in the housing touched the package tray metal. It arced slightly. I didn’t think much of it at the time as the light still works. According to the wiring diagram, that is not a fused circuit. It is triggered by the trunk latch and powered straight to and from the bcm. I believe it may have backfed and have hurt the bcm. All of the symptoms I see seem to be connected to or through and lead back to the bcm. Doing a little more circuit digging and should know something shortly.
 

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F.W.I.W. A long time ago, did the exact thing with the trunk lamp and it merely blew the fuse for that bulb and some other component/s. Had no ill effect on the body control module and this was many moons ago although that's not to say such is impossible.
 

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Discussion Starter #20
Was this on the G8? Reading the wiring diagram this morning that trunk light is not fused. It runs an orange wire that goes straight to the bcm. Did I misread this? The other strange part is that when this happened my meth pump began spraying with the vehicle off. I have the controller triggered on fuse F32 in the engine compartment which is listed as emissions 2. As far as I can tell this all backfed from the bcm. The pump is wired to the battery and fused and the controller is wired in the front fuse box.
 
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