There is definitely something going on with my solenoid because that relay works on mine. It clicks when I pull it off and on and when I finagle it a bit on my harness I actually see my dash light come on and off so it's set to overdrive on and yet I'm not getting overdrive.
I bet there's power going to the solenoid which keeps the light off but it's not tripping the solenoid.
When I have space today I'll pull that solenoid off. Or maybe I'll do this tomorrow. Can't miss my Bronco game after all. Go Tebow!
A pic of the relay for clarification. I'm still going to jump this at the harness then take it for a spin even though I hear that relay clicking.
I'm assuming it's #87 and not #87A.

 

So I went underneath my car today and saw the wire to the solenoid has been cut! So I reconnected it and took it for a drive and nothing.
So back on the car ramps to remove the solenoid. Had a ratcheting box with a good angle,a 12mm socket and swivel ratchet and guess what tool took it right off? My trusty combination wrench with that 10 degree offset on my box end. Maybe on 1988's there's more room but that 10 degree offset was plenty to remove it.
Sorry didn't think about taking pics.
I removed the small O ring from the tranny and kept the large one on. Marked the front of the solenoid with a marker so I won't try to put it back on the other way. Then I took the solenoid to my drill after discovering the connector fell apart on my hands and the rubber boot as well.
1/2 inch drill right to the small hole. Drilled down till it almost met the big hole.
Dremel connected the rest. Maybe a 2 minute job.
Then cleaned it out with an old toothbrush dipped in ATF fluid.
Installed,snipped the wire,removed the bypass wire on the relay. Light not coming on in the dash.
Drove it down the highway then I felt it shift to overdrive and smiled as I saw my tach read 2,000 rpm at 60 mph.
Thank you guys! This thread really helped me out!

 

Well this post seemed to jink me. My bride came home yesterday and told me the OD was not working. So I jumper-ed out the OD relay (15 to 87) and still no deal. Today I put it on the lift and checked for voltage at the solenoid connector and got 12V. I pulled the solenoid and did a bench test and it didn't work. So I proceeded to modify it . I also called Volvo and they wanted $231 for a new solenoid. I put the old modified one in and the OD works fine. I also plugged in the connector and I don't get the dash light. Looks like I'll go on line to find a new solenoid for under a $100.

 

Bump on an old thread. 91 940 turbo wagon AW72 235k mi. One bolt, the one that goes into a hole that goes clear through, corroded and was a toughie and needed a 6 point to bust loose. Good news is the rear crossmember was super easy to drop and a good idea for anyone. I was fearful of rust and transmission weight. Though I had a floor jack under the trans, I barely needed it as it just rested on the flex of the front motor mount rubber.

I yanked my solenoid out then brutally connected the two dots with a 4" angle grinder equipped with a skinny cutoff wheel. When one does this they need to be sure not to dig into the large o-ring recession.

I had been suffering flaky overdrive, approx half the time. The first time I had a problem I was sitting in unusual traffic for half an hour. Never overheated (the engine) but the solenoid probably got a good heat soak.

Now, here's a puzzler: My test drive was initially disappointing, hitting 60 MPH still in 3rd. Turned around and had OD back. Maybe I'm having a valve body issue. Maybe I got a grain of grit in the works that initially blocked the passage but worked its way through. Time will tell.

Clean full fluid, changed 5k miles ago. Old ATF looked great too.

 

a turbo almost certainly has a AW71 transmission. the AW72 has radically different gear ratios, suitable for the high revving 16V DOHC B234F engine.

 

whoops, i stand corrected. I remember it's AW-one-more.

 

Couple days later and working fine. Thanks forum!

 

I'm having the same issue on my 93' 240 wagon. I jumped pin 87 & 15 on the relay . Overdrive light still is on. The issue started after I replaced the ignition relay. One morning I turned the car on and the srs & overdrive lights came on the dash. I turned off the car & restarted the lights went away. 3 days ago. The od light stays on and I now have no OD. I did check the tranny fluid its still red & doesn't smelled burned. Although I havent changed the tranny fluid since I brought it. I got about 25k miles so its time to flush the tranny . I'm thinking should re check the ignition switch install see if its loose? Or is it the od in the tranny? Haven't checked the connection on the trans yet.

 

ok, first question is, does it actually shift into OD or not, even when the light is on? from a stop, accelerate smoothly up to 45 or faster, and you shoudl count 3 gear shifts if OD is working (1->2, 2->3, 3->OD).

the OD is enabled by a solenoid in the transmission. the solenoid power is the OPPOSITE of the dashboard light.... light on == no solenoid power, light off == solenoid powered. when the solenoid is powered, the OD is disabled.

common failure modes:
1) pushbutton in shifter gets erratic or fails entirely, or the wire to it breaks. hard to fix
2) relay fails, often can be repaired by resoldering relay innards, otherwise replace relay.
3) solenoid or wiring under car to the tranny fails
4) transmission itself has failed OD innards (but if 1-3 is OK, the light usually works properly, it just doesn't shift correctly). $$$ to fix, involves complete tranny rebuild.

if 1 is the failure mode, many people opt to disable the OD lockout entirely, this can be done via a kit IPD sells that replaces the solenoid, or you can take take the solenoid out and dremel a notch in the end to get the same result. then just remove the OD relay so the light stays out.

the relay is wired like this...
1) ground to pin 31 (black wire)
2) pin 86 green wire to pushbutton to green wire to pin 15.
3) pin 15 to blue-black wire to fuse 11 (powered with ignition on)
4) pin 87a to yellow-red wire to OD light to blue wire to ignition power
5) pin 87 to white wire to solenoid, solenoid to ground via its mounting.

pins 87a and 87 are wired together inside the relay. the relay connects 87/87a to either 31 (ground) when 'OD is off' (this lights the light but unpowers the solenoid), or it connects 87/87a to pin 15 (power) when 'OD is enabled', this turns off the light but turns on the solenoid.

when you jumpered 87-15 at the relay socket, did you leave the relay out entirely? then the OD up arrow light should NOT have been lit as 87a should have been floating.

there is a 3 pin connector (labeled "E" on the drawings) thats near the corner of the passenger footwell side panel and the center console and the tranny hump. has wires white (to the solenoid), green and green (to the button). the forward side of this connector goes to the relay and dashboard, the back side goes to the button and solenoid.

if you unplug this connector, on the back side, an ohm meter on pins 2-3 (green and green) should read 0 ohms when the button is being pushed and open circuit when not. on the front side, the white wire (pin 1) should be 'hot' when the OD light is 'off' and 0V when its 'OD disabled' and the light is on. that white wire on pin 1 goes directly to the pin 87 on the relay socket.

hope this helps (and hope i didn't make a mistake scribbling this circuit analysis down, hah!)

 

btw, 'replaced the ignition relay' ?? what ignition relay? there's a fuel injection relay which also controls the fuel pumps (and is commonly called the fuel pump relay), but there are no relays in the ignition circuits.

 

p.p.s. If my pushbutton was the problem (failure mode 1), I'd be quite likely to replace that button with one I put somewhere on the console and wired to those two green wires on that connector "E", because I drive alot in the mountains where being able to put the car in 3rd is a big helper.

 

Ok Here s the answers to the questions
first question is, does it actually shift into OD or not, even when the light is on? from a stop, accelerate smoothly up to 45 or faster, and you shoudl count 3 gear shifts if OD is working (1->2, 2->3, 3->OD).
No it doesnt shift into OD . about 60mph im high rpms on the fwy and the OD light is on the dashboard . I only feel hear two shifts.

when you jumpered 87-15 at the relay socket, did you leave the relay out entirely? then the OD up arrow light should NOT have been lit as 87a should have been floating
Yes the OD relay white one was entirely removed and the OD light still stayed on when I turned the ignition to the on engine running position

'replaced the ignition relay' ?? what ignition relay? there's a fuel injection relay which also controls the fuel pumps (and is commonly called the fuel pump relay), but there are no relays in the ignition circuits
Sorry Meant ignition switch that round piece where it plugs into the back of the ignition lock/key under the drivers steering column. I was thinking of going back in there and unplugging plugging it back in to see if that the issue or maybe its loose? Ill update you guys on this soon. I have nt checked the connections underneath at the tranny yet . I guess i need to get a ohm meter to check the push button switch as well. I got jury duty this week so Ill be doing a lot of city driving and dont need od but I still need to get this fixed. also will probaly do the transmission flush. I was reading there s two drain plugs on the automatic transmission . I was thinking of just draingin the drain plugs and flushing the rest out throught the transmission cooler at the top of the radiator . To do this install the hose turn on the car and drain the tranny into a bucket measure per quart and then refill tranny fluid at the top of the tranny filler? Do you have to do this at the same time your draining the fluid at the trans cooler or do u just drain first then fill at the tranny filler spot ? Ok Ill post updates soon . Hopefully Ill get out of jury duty early today Thanks Harold

 

there's actually no accessible connection at the tranny itself, that 3-pin connector I describe would be the best test point. remove the side panel of the center console on the passwenger side, and it should be right near the carpet or something, between the tranny hump and the passenger footwell...

tranny flush, get the tranny warmed up (drive 15-20 miles), pull the drain plug, and measure what comes out, should be about 4 quarts, replace plug, add that much fresh fluid via a tranny funnel into the dipstick tube. NOW disconnect the upper cooler hose at the radiator, hook up some spare hose into a large container that has quart marks, start car, and if you're smooth, you should be able to add quarts of ATF just about as fast as it comes out. once the stuff coming out is clear red, shut the car down and button the hose back up, then start it and check the level. the fresh ATF will be cold, so if its even on the tip of the dipstick you're probably close enough, otherwise add more, then drive 10-15 minutes and check again with engine idling and use the hot side of the dipstick, top it off

 

I checked underneath the tranny and the connections look fine. Today I noticed that my turn signals were not working left or right so I checked the fuse box this evening had two burned fuses. Two red ones. Luckily have two spare ceramic fuses . Replaced them and I immediately noticed the od engaged when I turned on the car! I'm still going to do the trans flush. It was as easy as that . I think one fuse blew at first then I think when I was messing with the od relay I must took out the turn signal fuse. I guess check your fuses first . Damm wiring..