I would do a current draw test on that battery first. I have seen that happen. Battery has enough to do some stuff then when you turn the key and everything turns on and creates a surge in the current draw it kicks the battery down to a level that can not power anything. Sounds like a short in the battery. A current load test will let you know.

The OVP would not do that much. It only protects and powers certain systems, like ABS and the CIS-E ECU.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....