Overdrive

I have a '87 Volvo 240DL. A few weeks ago I noticed the Orange Overdrive light was on. I figured it was a short. I kept pressing the button to turn it off, but no luck. Now, When I'm on the Freeway and going about 50 MPH I hear the Overdrive Hum. What is the problem?

Sorry for the late reply....

What do you mean you hear the overdrive "hum" at 50 mph?

Usually if the overdrive doesn't engage it's due to shorted wires or a bad switch.

Thanks for your reply. You know the up logo light below the dashboard. That is stuck on. Meaning Overdrive is off. Which takes more gas.:banghead: But, I think there is a short.

Usually the wires in the shifter get a short inside. Unscrew the bolts or screws holding down the shifter to the body and pull the shifter up a little, you should see the wires. My wires were all shredded and burnt so I just cut them off and added new wires. If the wires are ok then try cutting the wires off and twisting them together, this should cause the OD to engage (light goes off). That would indicate a bad switch. In a pinch you can just twist the wires together, tape them up, and put the shifter back in, problem solved, you just can disengage OD, which is normally fine.

There is a relay somewhere; I don’t remember where on the 240 perhaps next to the engine instead of on the inside, it’s behind the ashtray on the 740. These can start to play. I have this problem on my 740 at this moment so I have to press on it when it starts to fail. You can remove this relay, open it, let someone check and solder if he finds something loose.

Haven’t heard that the button have been the bad thing, often the relay. You can also cheat and go without the relay and drive with the 4th gear all the time.

No no no The problen is usualy the relay which is behind the dash and you must remove the glove box for access. Now if you are careful you can open the cover of the relay and spray it with a contact cleaner this may solve your problem. ( inside is a coil and contacts ) Or your going to spend 45-50 USD for the replacement
Sorry about a untimly responce but I just joined.