Engine not turning over suspect wiring.

[TXheat]

Battery is a new 650 CCA charged at 12.6 was starting up last week with no issues but now won't turn over,it cranks just wont start drops down to 12.4, black wire seems frayed at connection point not the battery terminal, all connections are clean and tight .Thanks for any help.

 

[TXheat]

Well I was fortunate enough to get a local mechanic to come check it, it turns out it was the starter it was OEM 36 years old and finally gave up the ghost, luckily I had s new one I bought at O'Reilly's a year ago, he replaced and problem solved.