I lost my overdrive suddenly on a cross-country trip today. The Dash light still comes on when I hit the switch, but no overdrive. It started cutting in and out at first, and continued to do so for about an hour, (60 miles), then quit working entirely. I looked for the overdrive relay inside the glove compartment, (to the left) but all I found was ductwork and clock wiring. Do 1980s (4-spd + Overdrive) have the overdrive relay in the dash? I know the engine and tranny in the car have been replaced with a mid 80s 230F and 4-speed. Is there a chance the relay may have been relocated during a swap? Any other possible causes? Any help would be greatly appreciated!!

Thanks to all who gave me advice! I both changed fluid and cleaned up/ re-pinched the wire contacts under the car, and she's back in business!! Replacement seals are definitely in the plan, too, but I'm going to hold off until the weather is warmer! Thanks again to all!! - Jorge

What is the exact nature of the "cutting out"? Does the OD instantly cut out and then back in? (or maybe stay out)? Or does it disengage and maybe re-engage in a halting, shuddering way? And is this worse after fully warmed up?

If former, I'd bet on electrical problems. Fault trace as per ODGuru's post.

If latter, hydraulic. Then, most likely is leaky piston seals as mentioned below, but solenoid is also a possibility.
--
Bob (81-244GL B21F, 83-244DL B23F, 94-944 B230FD; plus grocery-getter Dodge minivan, MGB, and numerous old motorcycles)

Jorge--

Try changing the transmission fluid. No guarantees, but I'm not kidding. I once had a cutting-out problem in the OD on my 1980 M46. New fluid cured it.

If your unit has tired seals in the OD, it may not be maintaining enough pressure to keep the OD clutch engaged--so it kicks back into 4th whenever it feels like it. New fluid will have seal conditioners and viscosity index improvers that may have broken down or evaporated from your old fluid--could help increase the internal pressure.

Good luck.

Doug Harvey

Wild guess that you have a slide switch.
Set brake, ignition on, engine OFF, gear in 4, OD switch ON.
Is there voltage at the OD solenoid? Check the yellow wire terminal first. If none, check the 4th gear switch on the right side of the tranny. Red wire feeds from gear switch, yellow wire goes to solenoid.

If voltage at the yellow wire of solenoid, clean and pionch the ends of the trminal and reconnect. Solenoid should click. If no click, check for voltage at the other solenoid terminal with the yellow wire connected. Voltage yes, check the ground wire. No voltage, replace the solenoid.

Duane

If it is cutting in and out that sounds like a pressure issue. With the car being that old I can almost be positive in saying that the piston seals inside the OD are shot. In the picture below... the seals on the 2 pistons on the left are old and crappy, while the ones on the left are brand new. The ones that are worn don't hold pressure. Not a big deal to replace those either. If you want some info on the process, feel free to email at runabout4fun@yahoo.com and I will walk you through it.

Kevin

an '80 would not have originally had a relay, no.

But who knows what was done in the swap.

if your shifter has a slide switch, you shouldn't have a relay.

If it has a push button, you should.

But who knows where the swapper put the relay? Not I!