I am having trouble deciphering the overdrive problem on my Volvo 740GL. The electrical button that activates the overdrive works showing the indicator light on and off. But the car does not go into overdrive. The car in an automatic transmission and if there's anyone who knows where the overdrive selenoid is located that would be greatly appreciated. I am guessing it's the overdrive selenoid that broken. The last owner did not change the liquids for transmission and oils. I changed it when I bought it and for the first day it was working then afterwards it stopped. Is the location of the selenoid internal within the transmission or separated for the unit?

I had a similar problem on a 1981 model 240. Overdrive kept disengaging when cruising at 60 mph.

I traced the cause to the overdrive inhibitor switch. This is on the outside of the transmission (on a 240 - assume 740 is similar). The switch prevents overdrive being engaged unless the gearbox is in 4th gear. On my car the switch had a worn contact which kept opening and causing overdrive to disengage.

It took me weeks to trace the cause, but only 30 minutes to replace the switch.

Mike Walker
London, England

The overdrive relay handles the light on/off separately from the solenoid on/off. So it's possible to get what you got - all light and no action.

Two problem areas. The relay has in it a circuit board with soldered connections that - over years of vibration and temperature changes - crack and stop properly working. It is an easy fix to re-solder the relay. Look in the archives for a post from Don Foster, has pictures, too.

Look here: http://www.brickboard.com/RWD/index.htm?id=328071

The other area is the wiring to the solenoid. I can help trace it in a 240, but 740s I don't know.

Good Luck,

Bob

:>)

It's located (externally) at the rear LH side of the transmission. You'll see the wire(s?) running to it. It is attached from the top down, so it's a bit hard to see what you're doing. It might be easier to replace by dropping the cross member and lowering the trans a little. (Don't let it drop too far as you might damage heater hoses, etc.)

Do you think that the selenoid is the culprit of the problem? or just wiring?

Here's how I diagnosed mine. Turn the engine into the run position but do not start the car. Click the OD button, your arrow should turn on and off and you should hear a very quiet click from behind the ashtray. Next, stick your head under the car as far as you can while still holding the shifter. You should hear a click from underneath the car. I could hear no click so I got out a 6' piece of insulated wire, shoved one end down into the positive battery post, then crawled under the car. I unhooked the little connector that is in line with the wire going to the solenoid and hooked up my 12 volts directly to the solenoid. I heard a click so I then knew the problem was in the wiring or solenoid. Re-soldered solenoid, problem solved.

--
Bob W.
15 Volvos ('58-'91)
445-544-122-240-740