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2009 G8 GT Maverick Silver, red onyx interior
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Discussion Starter · #22 ·
Very interesting. I did pull the interior light fuse to check it and it was good. I will check the vanity lights and the other fuse and see if they are working or blown.
If they are all in working order I’m not sure which way to go. My electrical guy here at the shop read through the wiring diagram and seems to feel the bcm is the culprit. I did the bulb on a Thursday night and the car was fine prior. I loaded it on the trailer for a track day Friday night and Saturday all of the other things happened. Nothing else changed. Not sure which way to go.
 

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Discussion Starter · #23 ·
Thank you for all of the info. It is all extremely helpful. Not sure if it will cure my issues or what to do next.
 

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Discussion Starter · #24 ·
Here is a short video of what it is doing. Be sure to watch the tach needle and the blipping of warning lights in the cluster. Very bizarre.
 

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You're welcome. Presuming the fuses, relays, and fusible links were already checked then perchance the issue could be the bcm. . However, hate to see another item replaced and it not remedy the issue nor am suggesting exchanging it at this juncture. In troubleshooting, learned to start with the low hanging fruit prior testing other things. How sure is he the bcm is the problem
 

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Discussion Starter · #26 ·
He seems confident. He followed the schematics and it seemed it all ended at the bcm. I will check some additional fuses tonight before putting it in. Rick Crawford tunes my car and made a couple other suggestions as well so I will check them too. I’ll report back what I find out.
 

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Just to gain knowledge, I opened the trunk an drivers sunvisor mirror cover. Lights illuminated at both locations as they should. The service manual says that all inadvertent lighting circuits, are monitored on the battery protection circuit. So when the ignition switch has been moved to the off position, any of those lights that were on will be shut down in about 10 seconds. However, they made a printing error again. Those lights "will" shutdown to protect the battery, but it actually happens closer to the 10 minute mark. So you could replace any of those lamps after the shutdown period has been reached without worrying about creating any shorting condition. But if you open any door again, that 10 minute cycle starts all over again.

There is a massive grounding location under the instrument panel. They say its located on the crossbeam structure for that panel. It shows "20" wires attached to it. That includes the exterior lights control knob, instrument cluster, an pretty much every component in that general area that had a ground wire exiting from it. Kinda looks like a suspect area for some of the problems your having. If its easy enough to locate that grounding location, maybe something less than an ideal condition might be found there (expecially if something was added to that grounding stud location).
 

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Discussion Starter · #28 ·
Any idea where exactly it is? I’d love to check it tonight.
 

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Evev thou the manual has a slew of drawings (showing where things are located) that G201 grounding location was not included. They only give you a printed statement of its location. From the manual >>>>> Behind the right side of the instrument panel, attached to the right inner side of the I/P cross beam. Probably not much help, but that's all I can find.
 

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Discussion Starter · #30 ·
This will be impossible to believe but it’s fixed. I checked that fuse circuit that should have been for the trunk light. My light was working and that fuse was blown. It obviously doesn’t control the light. I replaced that fuse and the car is fixed. I don’t know what it controls but my problems are now gone.
 

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"I" believe you It would be interesting to me knowing exactly "what" fuse you found bad (which panel, F # an amperage). This way I can study the manual a little, an possibly learn something important as a side benefit.
 

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That's interesting and now I have to go look for myself. Other than the trunk light arcing against the frame what would have caused the fuse to blow? Be back in a flash...lol. At any rate, glad the problem is solved.
 

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So, pulled the fuse and the trunk light went off. Replaced the fuse and the trunk light came on. Like the tree said to the lumberjack, am a little stumped. However, that's neither here nor there at this point and great the body control module wasn't replaced.
 

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Discussion Starter · #34 ·
It was the same F4 fuse for the inadvertent LED. It was blown but my trunk light and visor lights worked already. It is interesting that going through the wiring diagram it did not show a fuse on the trunk light circuit.
Either way, it is fixed. I may send the bcm back. Haven’t decided yet. It was only $129 for an ac delco one from amazon and free one day shipping with prime!
I truly want to thank you for the input and constant feedback. If you had not sent me the link, I would have NEVER checked that fuse at all. Grateful for the G8 community and the help.
GOPHERIT especially thank you for the guidance.
I’ll sit down and document the issues, what caused them and ultimately the fix in case any other members run into the issue.
 

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So, pulled the fuse and the trunk light went off. Replaced the fuse and the trunk light came on. Like the tree said to the lumberjack, am a little stumped. However, that's neither here nor there at this point and great the body control module wasn't replaced.
Glad you found the problem. I just changed my trunk light last night and it arched the same way(had a led light in there that was still partially illuminated and flickering even when off, so put a normal bulb back in for now). Still functions normally but would like to check the fuse anyway.
Any more info on the exact fuse and location?
Edit: sorry saw you just posted the fuse #/description. What fuse panel is that located in?

Sent from my Pixel 2 XL using Tapatalk
 

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Discussion Starter · #36 ·
It’s in the driver side kick panel. Reading the fuse description you would never think it could affect anything like the problems I had.
 

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Discussion Starter · #37 ·
Read the wiring diagram again today. It seems the F4 fuse is almost a backup fuse for the bcm if you follow the flow chart. Although my lights never stopped working I believe they may have worked because of the bcm still supplying power to it.
 

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Fuse F4 in inst panel box powers the trunk lamps, you prob have something shorting while hammering it,scanning snapshot mode will help find it at this point Also that ct, will remove voltage on the lamps after 10 minutes with ign off
 

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Ironically, the trunk light went kaput this morning. Pulled the F4 fuse before attempting to replace the bulb and in the process noticed a weak arc coming from the lamp holder even with the fuse removed. The bulb illuminated only after the fuse was reinstalled.
 

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Discussion Starter · #40 ·
I’m a little relieved I kept the bcm. I am going to replace it and have it programmed Saturday. Still thinking something must be wrong since the light still works with the fuse removed. But with the fuse out all of the other issues returned. I can’t help but think it was damaged somehow internally. Heading to the G8 winter fest event in Fayetteville next weekend and can’t take the chance of having an issue.
 
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