I drive a 1990 744 with automatic transmission with almost 170k. On sunday 11/6/05 my car stopped shifting into fourth gear. The car will get to around 40 mph and 2500rpm and will not shift any further.

For a very long time I have had a problem with the fourth gear lock-out light (the small orange arrow the points forward) going on and off on its own, but it never affected the transmission. From the way it behaved it just seemed the there may have been a slight short in what ever system controls that dash light. I do not believe there is any correlation, however, I felt it worth mentioning for the record because instead of being on sometimes it is on all of the time. Pressing the button on the side of the gear selector handle has no effect.

I plan to replace the transmission fluid and filter tonight and will report back my findings. Any comments or suggestions?

-Poritz

I solved all my worries with a "relay" change. It was the best $40 I ever spent. I had to drive on the highway to work at 47 mph for two days.

yeah, I've had the same problem, but mine is intermittent. it seems to be temprature related as the engine has to be fairly hot before it will kick into overdrive. But on the other hand sometimes when it is working and I shut the car off it will not re-engage. My problem is internal as I had replaced the solenoid and actually made up a fused switch and wire to bypass the switch in the gear shift handle.

At a minimum I have a valve body problem, and at the mavx a rebuild. time will tell.

regards

Woody

Thanks for everyone's help I really appreciate it. I thought the transmission was about to go. I was trying to prepare myself mentally for the thought of a new used car. It was horrible.

-Poritz

As long as that light is On, the OD relay must be Off — which means no power to the solenoid. So you can ignore that for now.

The simple circuit is:
1 - Fuse (power for everything}
2 - Switch (controls relay)
3 - Relay
3a - Relay ON = Solenoid ON (Arrow light OFF) OD active
3b - Relay OFF = Arrow light ON (Solenoid OFF) OD not active

If the switch doesn't control the light, the relay is the prime suspect.


--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

shorted or open wire to the overdrive solenoid.
There is no fourth gear. It's a three speed transmission with an overdrive.

It's also possible the solenoid itself is tango uniform and/or the switch in the handle (but switch is unlikely). and/or seals leaking in which case an overdrive rebuild is necessary. but overhaul is unlikely.

You'll have to look at the wire underneath and see if it's rotted or pinched.

You should be able to feel the solenoid work with engine running....it's also possible the trans fluid is so crapped up or varnished the Overdrive won't shift.

Thank you for informing me about the overdrive selenoid. Otherwise I would have had no idea. I had been searching for all the wrong information and thus found nothing in the FAQ. I am off to further investigate. I was within a hair's width of doing a ATF filter replacement. Good thing I didn't have to start that.

-Poritz

I just had the same problem; actually it's notyet solved. I just thad the tranny fluid changed by the tech program kids at the school wher I teach. I'm wondering whether either too much or too little fluid would cause this (My light for overdrive is not lit if the gear selector is in the drive position, even though the car won't move out of third gear.
--
Kevin ('98 v70 awd 65k; '92 745 turbo 127k)

You say that your car will not move out of third gear. Do you mean to say that it is stuck in third gear or that it will not shift higher than third gear?

-Poritz

It's an automatic, and when I put the selector in "Drive" with the overdrive button in the "on" position, the car does not shift into 4/overdrive as it should.
--
Kevin ('98 v70 awd 65k; '92 745 turbo 127k)

Just did OD selioind on a car I bought (91), If you can hear the selinoid click under the car (good sign). If not it is electical or bad selinoid.

Worst case, give up and put in a Idp blank for $35 and you cant down shift, but your OD will be back and you don't need any of the electrical stuff. Otherwise troble shoot with voltmeter for voltage down there at the connector on the right side of tranny. If voltage, replace selinoid.

I had a 240 I am parting, so it donated the selenoid. Good luck, write with any questions