Overdrive arrow light always on 240DL

I have done some research but I am feeling slow, it's not sticking
with me:

When the overdrive arrow light is always on does this mean the car is
not shifting into fourth at higher speeds or does it just mean the car
is incapable of downshifting to third at higher speeds for more power?

I.e., is this really a problem if I don't care about towing or getting
more power on hilly roads? I know it is probably a loose relay switch
or whatever, and I am going to have it looked at anyway, just wanted
your guys' opinions. It seems like I can count it shifting into four
gears when I drive over 60 mph, but it also seems like it runs
loud--but then it is a Volvo.

Thanks.

bhr

 

if the OD light is on its not going into OD, should shift into OD at about 40
,and if the OD is not working you should still be able to downshift into
passing gear,if OD is working car should be fairly quiet on freeway,my '88
likes to do about 80 on the freeway,my 81 didn't have OD and it was loud on the
freeway. mark

 

Its most likely your O/D relay thats faulty preventing selection of 4th gear
or the wiring from the button on the shifter to the relay, a common problem.

Jim
volvoadventures.com