My volvo 740 has a over drive button in the gear shift, the light stays on in the dash, it will hit 1-3 gears fine, but will not shift into the 4th

4th gear disengagement:

The 4th gear is engaged automatically after the transmission has shifted through 1st, 2nd and 3rd gears

at certain speeds and loads. By pressing in the button at the rear of the selector level, the 4th gear can be

disengaged, thus providing a three-speed transmission. As a reminder the

? light on the dashboard

glows. By pressing in the button again, the transmission reverts to four-speed operation and the

?
light shuts off.
This is straight out of the owner's handbook. What this indicates is that there may be a problem with the shift solenoid. On the highway, does is seem to rev high? Can you press the button on the shifter and have the light go out? let me know.

its a good idea to have the OD off lit up while driving in the city,it just keeps the transmission from shifting into 4th gear in the city and alot less wear and tear on your tranny from unwanted shifting,if you are over 40 mph just hit the button and let it go into 4th gear for the highway or a higher mph area,hope this helps

Remove your fuse block cover and look in with a flashlight, towards the passenger side rear you'll see a white tall relay. if you can get your fingers on it pull it out and crack loose the plastic housing, take the housing off and with a fingernail fileboard, clean the contacts between the closing contact. after doing this take a piece of fiberglas tape and tape closed the relay contact. This will leave the car in overdrive mode all the time. Why not, unless you want to pay nearly 110-130 dollars for the relay. The color "might" be black but the last one I did was white. Make sure by looking up the relay legend on the rear of the fuseblock cover.You didn't mention the yellow upwards pointing arrow on the dash while you're driving, that concerns me, although the last one was a 1990 740. Best of luck. P.S. The only reason you would not want overdrive is to pull a trailer up a mountainside and I don't think you want to be doing that with "this" car, right? Good luck my friend.Dana

This is a standard shift I am presuming if so this usually indicates a bad synchronizer in the transmission. if it is an automatic trans. it is a speed sensor malfuctioning.

check your fues box were it say gagues

It may be a faulty relay - usually behind the radio - it makes a clicking sound when you hit the button on the shift lever. Or it may be the overdrive solinoid which is mounted on the top of the tranny. Check all of your connestions first. One other thing - the wire from the shift lever overdrive button to the overdrive solenoid on the tranny may run over the top of the drive shaft - check for wear

Check your fuses,then replace the overdrive relay,if not this,they sale an bypass plate from IPB,for about 40 bucks,very easy to install.

Hi, chk ur rear transmission mount.

There isn't anything wrong with your car. This is perfectly normal. I have a 2000 ES300 as well as other people that I know and it operates in the same way. Overdrive doesn't mean the same thing for every car or transmission. In our case overdrive is simply a reference to the top gear which is 4th gear. When you switch overdrive off(which is depressing the button causing the O/D OFF dash light to illuminate,) the highest gear becomes 3rd because you turned 4th gear or overdrive off. The application scenario for this is usually mountainous terrain where a lot of uphill driving makes it more feasible not to up shift into 4th gear while ascending and descending. It will not switch back to overdrive or 4th gear until you re-engage it by turning the overdrive back on or repressing the button. Again, when the O/D OFF dash light is illuminated, overdrive which is 4th gear is off and the highest gear will then become 3rd. It will never shift into 4th gear while this light is illuminated or overdrive is off. When you press the button and the O/D OFF dash light is NOT illuminated overdrive is on and therefore it will shift into 4th gear as usual. This applies to all 97-2001 ES300's and probably any other car you drive tat exhibits this same type of change when overdrive is turned off.