I'm troubleshooting an overdrive no-go, trying to determine if the relay is bad, the 4th gear switch is bad, or both.

During warmer weather, the OD engaged just fine when the gear-shift button was pressed. Now that it's colder, it engages only when it wants to. But sometimes if I push the gear shifter back (toward the rear seat) while pushing the OD button, it engages. This doesn't always work.

What's puzzling is that this situation didn't manifest itself until the original OD went bad earlier this year. I since replaced it with a used unit which worked fine during the warm summer but not so much now that it's colder.

So, some questions:
- Could the relay be weak, causing it to get stiff during the cold?

- Can I replace the 4th gear OD switch from inside the cabin, or do I have to drop the tranny a few inches as I've read here?

- Does anyone have a spare OD relay to give / sell? I'm too broke to buy a new one unless I have to. I'm going to resolder the old one just to see if that does anything.

- Can I use another generic five-spaded relay for the OD? I'm assuming no but it can't hurt to ask.

As always, thanks!
--
Mike F - 1984 244 DL - 317,000 miles
Original engine, transmission, drive train, starter
Undergoing reconstructive surgery with POR-15

1972 142 S - The Yellow Brick - 135,000 miles
All stock except for Weber Carb. B20B engine. M40