Odd Parasitic Draw, 1996 Contour

[Whimsey]

OK, I got a chance to do the AC voltage test that StevieC attached the video of, thanks Steve!. With the car running my DC volts were a steady 14.5 at idle. When I measured AC voltage, at the battery it ran the gamut from nothing to over 90 volts and did it back and forth. I swear it looked like it got WELL over a 100++ volts numerous times. But it continuously and quickly varied. I checked the meter afterwards in an AC wall socket and it was a steady 116.6 AC volts without fluctuation. I'm thinking the diodes in the 22 year old alternator have given up the ghost. This hopefully explains the 'sudden death" syndrome of the new battery after less than 3 days unused. The battery was at 12.6 volts when I connected the negative terminal to run the test. From this test it seems like the alternator diodes are bad and I need a new alternator, not the end of the world. I can get a reman Denso for ~$110 from RA including the core return shipping. Any feed back from you "guys" is appreciated, thanks!.

Whimsey

 

[StevieC]

Good stuff and you're welcome for the video.

You can't go wrong with Denso IMO.

 

[Whimsey]

Well my great mechanic found my mystery parasitic draw that was killing the battery if it sat for ~2 days. The wiring harness going to the fuse box and the wires in the fuse box had their coating flake off exposing bare wires. Unfortunately it a common problem with my year Contour. I looked at getting a new engine wiring harness with the great help of bdcardinal & Trav. But there appears to be only 2 left in existence and they cost $2,000, and only sold to dealers as I understand

. My mechanic was able to salvage the wiring harness to the fuse box that was now bare wires by cleaning off the rest of the flaking wire covering and recover the individual wires in the harness with a heat shrink wrap wire covering. He replaced the 2 bare wires in the fuse box that were shorting. He did the repair and let it sit without starting for 4 days in his lot. This morning he went to start it and it started immediately

. He said only the heavy gauge wiring had it's covering flake off, the lighter gauge wiring is ok, no visible flaking. The best part is his repair cost me only $263, incl tax

. I've owned this car since new and took great car of it and it's in really good shape otherwise. It would have been a crime if a lack of a wiring harness, because it's old and initially defective, caused it to go to the crusher

. Thankfully it ended well

.

Whimsey