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Hi, I've got a pretty odd problem with my '99 Corvette electrical system. One day I went to start the car, and a ton of warning messages scrolled across the screen, like reduced engine power, shocks inoperable, check this and that and ect, and it would not start. The first thing I checked was the VATS system, which seems to have been bypassed already. So, second, I checked the steering column lock, which had also been bypassed. I charged the battery, and the car started... 15 minutes later (car turned off, just sitting there), the warning messages were scrolling across again. I put the charger back on, and it read 100% charged. So, I had the battery load tested at O'Reilly's and it was fine. When I got back from O'Reilly's and put the battery back in, no warning messages... everything worked fine... until about 15 minutes later. Same thing. So, I figured it was a grounding problem and started pulling ground connections and cleaning them thoroughly (though there was virtually no corrosion). What I'm finding is that when the battery is disconnected, and reconnected, I can start and drive the car with no problems, for as long as I want. When I turn the car off and it sits for 15 minutes to half an hour is when the warning messages reappear. So, I pulled the codes from the DIC when the car was acting normal (within my 15 minute time frame) and after the warning messages began to scroll across. The car throws no current (C) codes within the 15 minutes, but after that, it has no communication with the BCM or HVAC modules, throws current codes U1000, U1064, U1160, U1176 from the 58-SDM module and a few other historic codes, but I assume those are not relevant to this problem. It seems that all of those codes are communications error codes. At this point, it looked like there was definitely a problem with the BCM connections somewhere. I found a forum that listed the relevant fuses for the BCM, so i checked them and they were all fine. However, minifuse #25 did the same thing as disconnecting the battery. The cab lights came on, hood light came on, and the car acted totally normal... for ~15 minutes anyway. I hunted down the ground connector for the BCM, which was located near the battery terminal, and cleaned the connections. I saw on a Corvette forum post by Bill Curlee a problem with corrosion on splice pack 208 (SP-208). Mine was actually located in the cabin, and was very clean. As far as I understand, there is one more grounding location in the cabin that is relevant to the BCM, but I'm not sure where it's at. However, considering that there was no corrosion on any of the engine compartment grounding locations, I have my doubts that a cabin mounted grounding point would be corroded. If anybody has any idea what's going on here, I'd really appreciate some insight. I may be at the point where I just need to have it scanned by a Tech-II or something. Thanks!
 

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I have had many electrical problems with mine as well.. some were grounding issues, some were just module failures, and the dreaded short in the door accordian harness that causes any number of problems .. we have reached the expected lifespan of the electronics.. I think you will need a skilled tech to track it down , the fact that it resets when you disconnect the battery, I m betting on the BCM... and welcome to SV, sorry I can t be more help, but these electrical gremlins can be a real bitch
 

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check the plugs going through the firewall in the RF fender under the battery
 
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