1990 244DL, overdrive inoperative

SOLVED! See my below post!


Hi all.

A few months back I swapped in a junkyard AW70 into my car. All of the gears work, and it shifts decently for a 250,000 mile transmission.

Sadly my overdrive doesn't work! At first I thought it was because of my poor soldering skills, but I had a shop mess around with it, and try my known good solenoid from the old trans, and it still doesn't shift into 4th/OD.

I know the relay is good, because I can hear it clicking when I press the button. Oddly fuse #11 blew randomly after about 70 miles of driving, the light then came on. Shop put a new fuse in after they swapped the known good solenoid, and it hasn't blown yet in 20+ miles of driving, but still no OD.


Any ideas?



Thanks!

Could be the O'rings on the two internal OD pistons are worn.

That was the promblem with mine: I replaced them.

A bit of a PITA, but doable.

Do you have 12V to the solenoid on the transmission? Does that click when you press the button? It can be hard to hear it over the sound of the relay behind the dash so have a helper poke their head under the car with the key on but the engine not running.

Just get the solenoid bypass plate or dremel a slot in the solenoid you have. If it still doesn't work you know its something inside the transmission.

Mr. V said:

Could be the O'rings on the two internal OD pistons are worn.

That was the promblem with mine: I replaced them.

A bit of a PITA, but doable.

Click to expand...

Do you know where I can find replacement orings?

James10952001 said:

Do you have 12V to the solenoid on the transmission? Does that click when you press the button? It can be hard to hear it over the sound of the relay behind the dash so have a helper poke their head under the car with the key on but the engine not running.

Click to expand...

Just confirmed the other day that the solenoid wire is receiving 12v just fine. Will check, to see if solenoid clicks or not.

Hoggster said:

Just get the solenoid bypass plate or dremel a slot in the solenoid you have. If it still doesn't work you know its something inside the transmission.

Click to expand...

I've thought about it, but would rather have the ability to use the button.

UPDATE:

Turns out both of my solenoids, including the "known good" one were broken. Both had a frayed wire going into the top of the solenoid. One even caught on fire when it shorted out, and blew the fuse!

New eBay overdrive solenoid installed, car shifts into 4th again as it should!


How many mechanics does it take to diagnose a bad wire? Apparently 3.5!