240 Wont shift into overdrive

Hey all,
Yesterday on the way home it took my '90 240 quite a while to shift
into overdrive on the highway. This morning it never did.

I tried hitting the overdrive button a few times to no avail. Does
this indicate I'm going to need a new tranny or is their a possibility
it could be a fuse or switch???

My Haynes manual didnt have a clear answer.

Thanks in advance!

 

Did the arrow light on the dash stick on? Usually this fault is the
overdrive relay, the solder joints inside develop cracks. The wiring to the
solenoid on the transmission can be damaged as well. It's almost never a
problem within the transmission itself.

 

No the light would go on and off when I pressed the button.

 

Mine stopped working a couple weeks back.
The light burned out years ago... putting off that fix until I have time
to do the speedo cable and odo gear at the same time.

Maybe gonna go after the OD this weekend.
Question is, do I start at the switch (easy to get to but hard to get
at) or underneath at the relay (hard to get to but easy to get at)

Maybe put it off until winter. As long as it's 80 or so outside, the
relay works...

 

You need to check under the car to see if the wire coming out of the
shifter bucket is broken if it is then splice a new section in & your
problem is corrected
Glenn
Volvo Certified Technician
ASE Certified Technician

 

I had a problem with a 745 TD overdrive some time ago. As much as I remember the
pilot light and the solenoid are both activated by voltage from the relay. In my
case the the light behaved in a parallel manner with the mechanical switching or
nonswitching, sometimes switching/lighting happened many seconds after pressing
the button. This meant that the relay did not react properly to the button. I
changed the relay and everything worked well again. In your case if the pilot
light goes on and the shifting does not happen, the fault should be somewhere
between relay-solenoid cable-solenoid-gear. I would check the cable connection
between relay pole and solenoid conncector. I do not remember which number the
relay pole is but you can find it out from a wiring diagram. The cable between
the pushbutton and the relay inside the gear shift rod is also a weak point I
have learnt but that should be ok in your case.

Regards
Viktor

 

I wouldn't bother checking anytihing electrical without first checking
the fluid level.
Yours is a classic sympton of nothing more mysterious than a slight
fluid leak, that over time finally depleted down to a low level, of
just not enough fluid left in the tranny to aperate the OD.
The fact that at first it took extra long to shift is the telltale
giveaway.
It stopped shifting altogether just when the level depleted further.

 

A wiring short/ground is the most common cause of 240 O/D shift failure.

The positioning of the wiring running from the gear shift through the
floorboard down to the transmission has more than one weak spot. The wiring
itself is draped over the top of the tran housing, down the side to the O/D
solenoid visible from the under the car. You will have to get under and
inspect the spots where the wire can bounce up and down against the tran
housing, wearing off the wire insulation over time and causing a
short/ground. Also, where the wiring is molded into the solenoid is a spot
that road grease and debris can cause to break down, causing short/ground.

An exposed short/ground is easy enough to fix by adding insulation. You may
need to splice in a good repair wire section. To complete the repair, wrap
all the wiring inside one of those accordian style wiring tubes.

If the plastic/rubber molded section of the solenoid where the wiring is
attached is cracked/splitting, pull a good one from a pick-n-pull junkyard
for a few bucks, test it on a 12-volt battery circuit (you will hear a tiny
click switching it on, and again switching it off).

If none of the above are the cause, don't forget to check for a blown fuse.

 

Thanks for the suggestions. I didnt have time to check it this weekend
but I will be looking at it today. I will post if I find the problem,
otherwise its off to the mechanic. Oh well, first time I've had to
actually think about taking it to a mechanic in the 3 years I've owned
it. Not bad for a 20 year old car.

 

Been there, done that. It's most likely the OD relay has failed. You
can repair or replace it by taking out the glove compartment and looking
in to the left, towards the center console (assuming a left-hand drive
car; I imagine it's a bit different in a right-hand drive car). It's a
(IIRC) small white box.

If you're comfortable with soldering you can inspect the circuit board
inside for signs of cracking and resolder, or you can replace the relay
for pretty cheap. Take you about an hour if you choose to resolder, 20
minutes if you replace and have the spare on hand before you start. If
you do it again someday, it'll take you 10 minutes. The most time
consuming part is removing the glove compartment and putting it back in.

I've had to do this in three out of four 240s in our household over the
past 6 years. The one that didn't need it had a manual transmission.

 

YYMV of course, but in 100% of cases (n=3) at my house the cause was an
OD relay gone bad. It's a 10 minute fix, see my other post.

Also a distinct possibility and one that might point to a cause other
than a bad relay.

 

I've seen them in white, green, red, and orange depending on the year and
whether it's a manual or automatic. The manual transmission cars with
overdrive have a relay too, but it tends to be used less so it usually lasts
longer. With the automatic cars, the relay is engaged and supplying power to
the solenoid 99% of the time the car is running.

 

I should add that if the wire over the transmission chafes, it will often
cook the relay and then sometimes blow the fuse so you may have two or all
three common causes all linked to one initial fault.

 

That's not exactly the best case scenario.

 

I didn't know the manual transmission cars have an OD relay. That seems
odd in a 5 speed manual transmission. In the case of that car (an 1987
245), it got totaled perhaps before those problems surfaced- certainly
before the wiring harness self-composted. Man, that was a darn good
car- I miss that one.

 

I pulled the glove box and found the box. With the car on and I hit
the O/D button, the box makes a clicking noise. Does this indicate its
bad or working? I crawled under the car this evening and there is one
spot where it looks like insulation is missing. I think I'm just going
to bite the bullet and pay someone to do it.

Thanks to all for taking the time to reply!

 

In 1987 the non-turbo manual cars went to the M47 which is a true 5 speed
and has no relay. The earlier cars as well as turbos had the M46 which is a
4 speed manual with pushbutton electric overdrive.

 

That doesn't tell you either way, you have to pop the cover off the box and
inspect the solder joints on the circuit board, they will probably be
cracked.

 

fwiw.
I popped the relay out tonight and looked at the joints closely. No
apparent cracks (to these 47 year old squinties anyway.)
Sweated the ones that looked questionable.
Put it back together. Now I hear clicking at the relay and under the car
when I push the button.
Whatever I touched, musta' fixed it.
Just once though, I'd like to see a crack instead of randomly touching
up the joints...