240 Wont shift into overdrive

I see this a lot in repair in general. When the joints get bad enough you
see cracks, but all it takes is a microscopic crack between the component
lead and the solder for there to be enough resistance for the thing to not
work.

 

The earlier cars as well as turbos had the M46 which is a 4 speed manual

....which can fail too... The OD on my M46 stopped working exactly in the
same way as tlr1000's did. At first it popped out of the OD without
warning - that's pretty unconfortable - an later it stopped working. I found
out that the wiring from the relay to the switch on the transmission (or the
switch itself, havent'checked it yet) has a defect. I have made a new wire
from ground and connected it to the relay. This enables me to operate the OD
again - but now in all gears...! I must be very cautious and check the green
lamp, otherwise it will stress the OD. But it works until i have the time to
check under the car.

 

I was surprised at how many traces there were on this relay. Lots of
pins, close together... Tough to get my soldering copper on some of them.
The biggest blob was the one holding the body of the solenoid to the
board, (presumably) the ground side of things. It was gray, like solder
gets when it's been worked/fatigued...
A couple others had lost their shine and some looked to have resin
inclusions around the pins.
Anyway, worked flawlessly on the way to work this AM so I'm happy.

Now I'm going to have to revisit my turn signal relay and touch it up
again. First time through didn't fix it.

 

Just a follow up. I took it to the local Volvo specialists and they
told me the overdrive solenoid and its O-rings are bad. They wanted
$420 frickin dollars to fix it. Needless to say I went and got it
without having it fixed.

Question now is, I found new solenoid's on Ebay for $95, including the
O-rings, or do I get it from somewhere like IPD or Swedish Parts
Wholesale?

 

You can get it anywhere, it should be the same part. Replacement is pretty
straightforward and can be done by a novice in an hour or so with basic hand
tools. Hardest part is getting the car jacked up and supported or on ramps.

 

Had the same problem. Fixed it by getting a nifty little "over ride" plate
from IPD. The shift solenoid actually works to keep your transmission from
shifting into 4th gear (overdrive). By using this little plate the
solenoid's function is bypassed and the tranny will always shift into 4th.
The button on the shifter no longer actuates the solenoid mechanism. The OD
button is really only of use when decending a long grade or when pulling a
trailer and not really necessary for most driving.