Two weeks ago, I had to replace the overdrive relay in my 1989 244 GL. $80 and about 750 miles later, the overdrive went out *again* while I was driving today.

I initially thought the relay had gone out again. The symptoms (won't shift above third, light on dashboard on, won't go off despite pushing OD button on shifter) were the same. However, when I tried to turn on the rear defroster, it wouldn't come on. For some reason, I thought that the rear defroster and OD were on the same fuse.

When I checked the fuse box, the labels didn't say anything about the OD and defroster being on the same fuse, but the OD fuse was out. Thus, I'm very happy that I (probably) won't have to spend more money to replace the relay. Tomorrow I'm taking a trip to some auto store nearby to get new fuses (I went through lots of spares before getting my windows fixed).

However, I think it's strange that I keep having the same problem, just different causes. The first time, the relay went out just after I had briefly turned off the OD (forced it to downshift to third from fourth) and turned it back on (to allow it to shift back into fourth). I'm not sure whether my action was related to the failure or not, but I got it replaced and everything worked fine for the past two weeks.

Today, when the fuse blew, I had gotten the car up to cruising speed and had just set the cruise control at a comfortable 75mph. After maybe thirty seconds of that, the light came on, the car dropped from fourth to third gear, and I presume the fuse blew.

Does this problem happen because of something preventable?

Could there be a short somewhere? Is the OD relay perhaps faulty? Is the *fuse* connection faulty?

Finally, to conclude this long post, what should I do if the overdrive fails while I'm in the middle of a fairly long-distace trip again? Today, I still had to drive about 180 miles, most of it on the interstate after the OD failed. I kept my speed down (not more than 70mph), but what's more important was keeping the rpms low (enough). The cruise control (which performed flawlessly, thankfully) kept the rpms at about 3500, which is a lot higher than I would have liked.

Were those speeds/rpms low enough, or have I risked serious damage to the engine? I'm thinking an oil change will be due soon (checked over Christmas, looked pretty clean, and I haven't driven much else), but is there something else I should check to evaluate for/prevent problems?

I love my car, and I hate it when I have problems like this one that (make me) risk its well-being!
--
'89 244 GL--25/22 ipd sways, Alpine head, Eclipse front speakers