I know its a simple question, but its one I can't find an answer to. I've heard theres wiring diagram books for these cars, that brakes down every circut; Could someone tell me were to get one? I know a wiring diagram willn't help me out in locating relays, but it might help me out with some other issues. For example, I've got what appears to be a relay right next to my windsheild washer pump, thats about 3" long 1.5" wide and 2" tall. The wires have been cut right off, so I have no idea what its for. Any ideas on that one? Thanks in advance

 

Most of the chilton manuals have wiring diagrams in them and can be purchased at any auto parts store. (usually a special order item for Volvo) also you can check you local library and they have all the chilton and other specialty books for cars with the wiring diagrams in them. The only cost would be change for the copy machine because you cannot check the books out so you will need to copy the pages. Hope this helps .

 

Anyway you can post a pic of the relay?

The overdrive relay should be Up behind the center climate vents. You will need to remove the glovebox to get to it.

 

Thanks guys -
Unfortunatly my camera decided to take a swim, I bet the crabs are having fun with it right now. I can tell you the relay is more like 2' long 1.5" wide 1.5" tall and theres three wires coming out that go down to a wire restraint directly accross from the alternator on the passenger side wheelwell. The three wires are red, green, and black, also its mounted just in front of the washer pump. I can get you the part numbers on it if that would help.

 

Is it a black relay with f sockets for wires and only has 3?

 

Its unpainted steel(silver), Theres three male tabs on the bottom that go into one socket which the cut wires come from. There's a peice of tape or ribbon thats going around the center which has the numbers 1234510. Underneath the tape is VOLVO IMP which is painted on the relay, or whatever it is.

One more thing on the OD relay, What year range can I use on my 78'? I was looking at a few on ebay and it seemed like they all had different year ranges(I believe one said 75'-90'), some were orange, some were silver, some were black, but they appeared to all have the same prong configuration. Whats the deal? Does it matter? Thanks

 

As long as the configeration and the Numbers for the prongs match up then it will work..

 

Okay, I went to my pull-a-part yard today and was able to get two overdrive relays(one was 30A, the other was 50A) and found them behind the center vents like you said. Both the donner cars were of roughly the same age as my car, one was a wagon, the other was a sedan. So I went to find the overdrive relay in my car and it wasn't there!. I was able to track the two sets of wires from the shifter, up the center console and behind the instrument cluster!?! So I geuss my simple question got a little interesting. I didn't pull the instrument cluster, because by the time I tracked the wires there, I had already spent an hour and a half looking around and my interior was in peices. Any ideas were the OD relay could be? I know my car has OD, I can find everything else for it to work!

I also found that my switch wires rubbed on something(output shaft most likely) and chewed through one of the wires. I tried reconnecting the wires to see if I could get any life out of the OD, and didn't get anything. I was in park and the key was in the "run" position. If the relay was good, would I have gotten something; a green light, a click of a relay, something???? Do I need to be going over 45 MPH to get it to work at all? I still need to find the OD relay(It will go out eventually) regaurdless of the sheared wires in my shift boot. Any help would be great.

 

If it still somewhat works when you use the switch listen for it to click and try to follow and find it.

 

Thats the problem, No click, No light, No relay. Thanks for the reply

 

Im not sure then.

 

Hey, I think I might have a problem with my overdrive switch on my Volvo 240(automatic trans) also. When I press the button the over drive light DOES comes on in the dash but I don't feel a jerk or a change when on the highway. I don't notice a change in the sound of the RPM's ethier. Does this mean my overdrive doesn't work? And is going to hurt my car if I don't use the overdrive on the highway?

 

Check the overdrive Soleniod on the trans.

Eventually yes it will hurt the engine being at the high RPM for so long.

 

how can you tell if the overdrive is working or not? And about what speed do you have to use it at?

 

You'll feel it shift and lower your RPM's just like shifting another gear. Above 45 MPH.

 

If you have a tach make sure you aren't taching like 5,000 when doing like 50 to 60.

I may not be 100% correct I don't drive one everyday.