Volvo: Overdrive fuse pops, automatic transmision, fuse box

Question
Hi,
I have a 1987 240 DL with Automatic Transmision w/ OD button. My OD wasn't engaging after I left work yesterday morning and noticed that my son's water bottle emptied itself all over the Emergency Break / Seat Warmer button area. I went home, took everything apart and dried what was wet (not very much surprisingly.)
Fuse still kept popping, so I disconected all of the tabs going into the fuse source for OD / rear demist / seat heaters. Turned on the car and plugged them in one by one until the fuse popped. Thick plastic one was okay, second metal tab was okay, but the last metal tab, that is first visible when you open fuse box, popped. Is this control for the seat heaters or OD button? I've had some tranmission work done (ran over a rock and wiped out the cat. converter, trannie fluid pan, pipe to first muffler, and tubes from radiator to trannie.)$1500 to replace.

I would take it to my mechanic, they're great, but it could be 3 different things: Bad OD relay, loose cable at the selnoid, or the whole OD located at the trannie. They charge so much and if it is something like the relay switch or loose cable, I can change it, but if they do it it will cost me starting $400 vs $45.

Please help educate me,
Becky

Answer
Hello Becky! The first thing I would check is the wire going from the shifter to the OD solonoid. It is probably frayed and hitting the body ot the side of the trans. It can be seen from under the car near the shifter linkage or shift bucket. Let me know what you find. I'll be here if you need me!

Jimmy