91 240 automatic. I've had the car awhile now and the overdrive has never worked. The overdrive button was missing so I assumed that was the issue. I have replaced the button. When I press the button I can hear the relay clicking behind Dash but the overdrive light does not come on. The light has never come on. I crawled under the car and can see no obvious wiring issues. Does this mean the overdrive solenoid itself is the problem? Would like to get some opinions before I order a new one. Just to verify, the car does not shift into overdrive even though the light on dash is off.

 

you can test if the overdrive relay is working by taking it out and jumpering pin 15 and 87 with a paper clip. does this allow the trans to shift into 4th gear? if so the relay is bad.

 

If u can hear the relay clicking when u push O/D button does that mean it works? Or it can click but still not be working?

 

when you ufirst turn on the ignition, before you start the motor, does the OD light come on? if not, maybe someone removed it.

note, the OD light *ON* means OD is *OFF*, and you are in 3rd gear, its confusing. the light means OD is disabled, and only if the light is OFF does the car shift into OD/4th as needed.

drive 45+ MPH at a steady speed, push the button, do the RPMs chage? push it again, do they drop back down to where they were? even if you don't hav a tach, you should certainly feel/hear it in the engine...

 

well nothing surprises much with these cars so i'll say maybe. if you bypass the relay with a paper clip and the trans does not shift into
4th, then the problem lies elsewhere, possibly the wiring to or the solenoid itself.

 

if the system is working correctly, when the light is ON, the OD solenoid on the transmission has NO power, and the 4th gear aka OD is disabled.

when the light is OFF the OD solenoid IS powered, and the 4th gear OD is enabled.

the solenoid in turn opens a hydraulic passageway when its energized, this passageway allows fluid pressure to reach the OD clutch inside hte transmission and engages the 4th/OD when the pressure decides its time.

assuming the control system (button + relay) is working correctly, there's 2 more failure modes... 1) the solenoid is stuck closed, so you will never get OD regardless of the relay, and 2) the fluid passageway is clogged (all it takes is a grain of sand sized particle in the ATF).

failure mode 1 can be fixed with either a new solenoid, or you can get a brass plate with a channel milled in it that acts like the solenoid is always on. I think IPDusa sells these bypass plates.

failure mode 2 would require cleaning out the transmission passages... I've heard that sometimes you can SUCK out the openings to that solenoid plate and clear whatever blockage.

 

thank you for the information my next step will be to get under the car and closely inspect all wiring. If that doesn't solve it then I will be removing the solenoid. Will probably end up cutting a Groove in the solenoid.

 

your next step should be to bypass the relay and see if that lets the trans shift into o/d. it's much easier! then if that does not work you could take the next steps as pierce has so succinctly put it. there is one other solution if it gets to failure mode 2 which is to blow out the blockage by slightly opening the solenoid plate and then starting the engine and briefly putting it in gear. this is messy but if everything else fails then worth a try.

 

before hacking the solenoid, first, check to see if the OD light even is in the dash, it should light when you turn on the ignition before you start the car.

if the light IS good, and its not toggling with the button, there's a problem with the relay circuit.

finally, verify that the OD solenoid is getting power when the OD should be 'enabled'. if its getting power, then either the solenoid is stuck or the internal passages in the transmission are clogged.

I find being able to disable the OD on demand is extremely helpful when driving in the mountains, and when towing small trailers.

 

bypass it by jumping pins on relay plug with paperclip?

 

OD light does not come on when key is turned on. I just replaced odometer gears and all bulb sockets had a bulb in it. I guess that light could be burnt out. I live in Fla and don't tow so don't really need to turn OD off.

 

make sure fuse 11 is good... with the ignition on, both sides of teh fuse shoudl be hot relative to a ground

find and remove the OD relay, and jumper the relay socket from pin 31 to pin 87a, and turn the ignition to II (run), and the OD light should light if its a good bulb.

Now, remove that jumper, and instead jumper relay socket pin 15 to 87, and take a test drive, from a full stop on an empty road accelerate smoothly, you should feel the shifts 1-2, 2-3, 3-OD. OD will shift into as low as 30-35 MPH if you're coasting with very little throttle, and under mild acceleration probably should shift into it around 45 MPH.

 

I read all the above .My 940 began intermittently NOT going into overdrive ,made no difference either warmed up or not and now it stays in 3d ( no OD ) .Overdrive light stay on and pressing 'Overdrive ' button makes no difference .Car has only 124 K on it ,1993 model .
From reading all the above my options are 1) check / jump relay ( WHEREVER THAT IS ! ) ...2) remove solenoid and blow out passages ( WHEREVER THAT IS ! )...3) remove solenoid and get the IPDusa block plate .

My questions : Where is the relay , where is the solenoid ,how do you "suck out " the solenoid or do you "suck out " where solenoid goes in ?

 

it's relay 'I' in the diagram 2nd row in behind the fuse block

https://www.matthewsvolvosite.com/fo...ic.php?t=23868

jumper pin 15 and 87 with a jumper or even a paper clip - see if OD works


assuming fuse 11 is ok that should be your first step on the troubleshooting before numbers 2) and 3) because it avoids going underneath the car.

 

Thank you for the help !

 

actually it might be fuse 12 that is in the circuit that controls it on your car
let us know what happens !

 

i woudn't mess with the solenoid until you get the light to toggle with the button. most common failure modes are the relay itself, or the wiring to the button on the shifter.

now, if the light toggles, and you still don't have OD, then its probably an issue with the solenoid and/or passageways inside the transmission. the solenoid is on the side of the transmission. when the light is ON, the solenoid is off, and the passageway is closed... when the light is OFF, then the solenoid is ON, and the passageway is open... open passageway allows transmission to automatically shift to 4th/OD when the RPM and throttle is appropriate.

 

электрическая схема

 

 

um, this thread is talking about the automatic OD, which is a different beast than the manual OD.