Baffling Problem

[89SHOMAN666]

Ok have a problem that I really need to diagnose. My fathers 92 SHO started around 6 months ago with some sort of a power drain. You will go to start the car and it will have a battery voltage of around 10.5 volts. I initially figured that it might have bad diodes in the alternator, so I put on a good used alternator plus a new battery as the old one was down a cell. The problem reoccurred, so I thought maybe it is having a stuck relay, so I replaced the relay box with a good used one. Well this was not it, the problem reoccurred and ruined a second battery. During this time I periodically checked the battery to see if I had a larger than normal drain. Well it always had a normal amount. Then, I decided maybe an issue with the ignition switch so I replaced that. It reoccurred again this afternoon. This is really starting to infuriate me as it never shows a greater than normal drain. My father has to drive this car 750+ miles a week so he is really getting ticked as well. Plus every time this problem occurs it is ruining a cell in the battery. Another thing to add to this was about 1 year ago this car got a really bad miss. Turns out this was caused from a relocated ground that got a cold solder joint and grounded out against the firewall. After this I had to replace the computer as it had been shorted. Car ran great after I re-soldered it until this problem.

Only thing that I can assume is that we did a heater-core around 6 months ago. My only idea is maybe we did something wrong under the dash, but I would have assumed that it would have manifested in some other way. Everything works perfectly dash wise so I am at a loss.

Any suggestions or advice would really be appreciated. I am going to let my pop start driving my 94 ATX now so that he doesn’t have to worry about his 750 mile commute as it already really sucks

Thanks in advance,

 

[doclees]

Find a mechanic that specializes in electrical problems or find the other recent post that talked about ohm-ing out a power drain. Electrical stuff is the most frustrating.