My overdrive light has been going on & off lately. It got to a point where it just stayed on all the time. I couldn't get the old relay to work anymore so i went to the salvage yard & got another one. I plugged it in & it did the same thing! I was thinking that it needed a new overdrive solenoid. I then started to wiggle the relay a bit & the orange light went off & it works fine now. The question i have is it must be a bad connection to where it plugs in. Is there a easy way to fix this because the only way the overdrive relay will work is if i really mess with it. If i plug it in all the way it won't work.

Thanks,
Scott

 

Update.......I went out to the car & started it & now the overdrive light is back on!! I moved it around & it won't go back out! I know it's the connection is not good. Can anybody help me figure out how to get a good enough connection? Please!!!......anybody?

 

I assume this is an automatic, like an 3speed + OD AW71? The board that the OD lay plugs into will (if you remove the section of facia above, with the radio and the ciggie lighter) pull out some way, so you can have a look at where the wires leave the underside of the board. Alternatively, you can look carefully at the spade connectors in the board and make sure that the relay pins are fitting right in. If not, you could try some long-nosed pliers and slightly pinch the connectors, although it might not be so easy to do this. I assume that once the relay works, the OD solenoid at the transmission is working OK. It might be worth following the wires from the board to where they disappear out and under the car. 940 wiring is generally good (unlike the 80's 760/740 nightmare), so it could be a poor connection rather than insulation failure. I do sympathize, I have had these kind of electrical voodoo stuff go on a few times.

I remember that there was a button on the right side of the transmission lever in AW71s where you could switch off the OD so you could tow in 3rd...it might be worth checking the wiring to that as well...I am sure others will have some better ideas. Good luck with it

 

mikesredheap, Thank you for getting back to me!! This is really pissing me off! I can't get it to make good connection to the board. If i can't get it to work i'm going to have to order that overdrive bypass unit. I'm just to broke right now to order it.

 

um, what year and model Volvo is this? 240's are wired somewhat differently than 740/940's, and the relays are all in different places.

I'm assuming this is an automatic transmission on a 80s or newer car. that would be an AW70 if its a non-turbo or the heavy duty AW71 if its a turbo. if its one of the twin cam 940s, its probably an AW72 (same as aw71 but with different ratios)

that light indicates the overdrive is DISABLED. not that its on. the only way to know its actually shifting into overdrive is to feel it shift and hear the engine RPMs drop. my 740T and 240 will both shift into overdrive if you're just cruising steady somewhere around 40 or 45MPH.

 

My bet is that the relay that you pulled from the junkyard is just as bad as the one you pulled from your car. These relays are notorious for developing cracks in the solder joints of the circuit board. Pull the relay apart. Check the bottom of the circuit board and re-solder the joints on it, put it together and try it out. Most times the failed joints are the ones connecting the coil to the board.

Good luck

 

First check the wiring under the car. A lot of times the wires get melted and split apart or get exposed. This could cause the light to go on and off. If wiring is in tact and good you might have a weak or bad OD relay. While the OD light is on and car is running, give the dash a knock right above where the relay is and see if the light goes out, do it a couple times with decent force but obviously you don't want to do it so hard that you break your dash. If the light turns off you know your OD relay is bad. If light stays on replace the relay with one you are certain is good or new. If light still stays on after that, you most likely have a bad OD solenoid. Good luck!

 

I found out what it was. It's where the overdrive relay plugs in. I took one of my overdrive relays apart thinking that maybe it was bad but it was fine. I left the casing off of the overdrive relay & plugged it in & tipped it back & it works fine now. Just a bad connection is all it was. I hope it keeps working for a while otherwise i will have to fix the wiring. At least the relay will run cooler with no case on it. If i left the case on i couldn't get a connection at all.

 

You can remove each spade connection from the plastic holder with a pick. You just have to bend the little metal locking clip down and it will slide right out. Tighten each one with a pliers, push locking clip back out then reinstall. This will insure you have a tight connection. Make sure you do one wire at a time or remember exactly which one goes where or you risk shorting out and melting wires...not good. Good luck!

 

Thanks Volvoguy! I'm going to do that if it acts up again, but as long as it is working for now i won't touch it! lol

 

I am having a near identical problem with my 91 740 a/t. OD light goes on and pushing button on the stick doesn't make it go out, or shift into OD.

Where is the OD relay located?

 

on a 740 its in the main relay panel, which is behind the ashtray. I think you need to take out the pocket above the ashtray out too as its behind the fuses too.

I believe its relay I, middle row far right.

 

Thanks, there's ten relays, black, white, red and blue.

Anybody know offhand which one is the OD relay?

 

I said, I believe its Relay "I", the far right in the middle row. Thats where it is on my 1992, anyways.

 

Thanks, don't know how I missed that in your post.

 

Pulled it, popped the top, plugged it back in, started the brick, manually activated the relay and...

It was the relay!

Now I just have to figure out what sort of fix to do... Proper, or maybe a toggle switch on the dash.

This is a nice relief, as we are traveling for Turkey Day, and I wasn't looking forward to losing several MPG on the highway.

Thanks!!!

 

hmm, lets see. the pushbutton is wired between relays pins 1 and 4, 1 is 'hot' when the engine is on, so if you remove the relay, and connect a volt meter between relay socket pin 4 and ground (relay pin 2 would work), turn the ignition on, when you push the button, you shoudl see 12V if the button is working. if you don't, then the button is bad or its the buttons wiring. thats rather an SOB to get out of the shifter.

the OD button thats on the shifter has a 2 pin inline connector, which is somewhere under the console, vague arrow points to somewhere forward of where the shift lever is, and it has a blue and a brown wire on each side of this 2 pin connector. there's another 2 in connector there that has a yellow wire on one side, thats something else.

if the button seems OK, then I'd try swapping the relay with another 740/940, afaik they are all the same.

note this is NOT a simple relay on my 1992 diagram, anyways. its got electronics in it, and its connected to the kickdown switch... oh, the kickdown switch optional 'AW 71/72 certain markets'...



hmmm. *MAYBE* pulling the relay, and putting a jumper wire between pin 1 and 3 would work as a hack, this would leave the OD lockout completely out of the circuit, the OD would work automatically purely on hydraulics in the tranny.

 

Glad you mentioned it, because on this '91 the relay has an IC and a couple of capacitors in it. Not sure what those do. Seems like completely unnecessary complexity to me.

At this point, I've got a piece of paper holding the relay on OD, my plan is to just *not hit the OD downshift button* until I "fix" it.

I'm tempted to just defeat the shifter button as I don't tow with this vehicle and would rarely need to lock out the OD, and would rather not wear out that solenoid from unnecessary use - and need to replace it.

I'm thinking *maybe* pull the connector off one of the relay pins you indicated, and leave the relay as is (permanently set to "OD on"). Thoughts?

 

the OD relay functions as a toggle. one pulse from the button switches it on, another pulse switches it off. a simple relay wouldn't do that, it requires some circuitry, and the capacitors provide a time lag so it doesn't 'bounce' if the edges of the button press are noisy (as they too often are).

 

oh, and pulling a contact off won't cut it, you'll need to jumper it as I described. the relay connects its output pin 87 to ground (pin 31) when its 'off' (light on, OD disabled), and connects it to power from fuse 12 (pin 15) when the relay is 'on' (light off, OD enabled). the light comes on when the OD solenoid is off. the light goes off when the OD solenoid is on.

so, remove the relay entirely, and connect where its pin 15 was (labeled pin 1 on my drawing) to pin 86 (socket pin 3) to act as though the relay is always on. or, jam its contact plate down, which you've already done in testing...

I'm suspecting that either your relay's electronics are zapped (there's a chip in there to implement the toggle function) or the wiring to the button is shorted (thats brown and blue wires) or the button itself is shorted.