Well for the 2nd time my 740 odometer stopped working and started up a few days later. It happened once before and I used the press the service button and then the trip button and it started working again. This time it didn't so I was thinking after 383K miles that the gear was shot. Was going to order a new gear but low and behold after a few days it just started working again. So has anyone had this issue and if so has it been fixed. Just curious . Wondering if it might be an electrical problem with the stepping motor that turns the gear.

 

Common occurrence. The capacitors weaken and begin to fail intermittently, now and then, sometimes, little by little, etc.

 

I had my odometer fail a while back (1989 740) after I pressed to reset it. I replaced the gear and it worked perfectly for about 3000 miles.

Just recently it’s started to get stuck again, roughly every mile it seems to stop until I give a firm thump on the top of the dash, I’d be interested to know if this is a mechanical or an electrical issue. Any thoughts?

 

You have mechanical and electronic parts. If you mess up the gear, that's different than the capacitors which act up in mysterious combinations...

 

and different year 740/940 have different speedos. the 91/92 are probably the most problematic with leaky caps, but in my case at least, this killed the speedometer so it intermittently wouldn't read over 43 or so MPH. I took mine carefully apart, replaced *all* the suspect caps after carefully cleaning the capacitor leakage off the printed circuit board, and it was STILL messed up. grrrrrr.

 

So far this has not affected the speedometer but just the odometer. I did the press the service button and then the odometer reset button several times and don't think I have a gear problem. As long as it still works I'll live with it but if it fails I'll have it rebuilt . Right now I'm getting the front end rebuilt.

 

I'm having similar problems with my 940. The speedometer and odometer work when they feel like it. Frequently not at all, sometimes after driving for a continuous half hour or more. (which I'm not doing very much of these days -- just groceries and back to my quarantine enclave) I wouldn't care too much about the speedometer, except that it takes the cruise control with it when it fails, but the odometer is helpful for doing maintenance and the gas mileage has really suffered. When it runs at all, the speedometer is accurate.

My trip odometer has an entirely different (and almost certainly mechanical) problem. It sometimes sort-of moves but doesn't count miles, and when I push the button, some of the digits move and some don't, and something inside feels crunchy. (so I don't push the button any more) I'm guessing there's a piece of debris stuck in there.

Two questions:
Anybody have a list of the capacitors needed? It would be nice to have them ordered and on hand before taking anything apart.
Anybody willing to reveal the secret for getting it out of the dash? It's not obvious and my Haynes manual isn't very helpful.

 

if its a 1991-1992, there's an article on the net somewhere on repairing those.

to remove the instrument cluster, you first remove the metal bezel around it, if you closely examine it, you will see slots where the metal hits the plastic window of the cluster, midway up each side, you insert a thin metal tool, like a 1/2 or 3/4" wide putty knife, into that slot, and depress a spring beside it, then pull that side of the bezel towards you a bit, then do the other side the same, then the bezel comes out. once the bezel is out, it exposes the screws that hold the cluster in place. be sure to note all the connections and plugs on the back of the cluster so you get the single wires back in the right places.

Notes on 740/940 Volvo Speedometers ah, thats the article.


when I tried to fix my 1992, I did NOT remove the chips as shown, and clean under them and repair any damaged traces hidden by the chips, and my repair did not go so well.

btw, IMHO, get the capacitors from digikey, they are cheaper and easier to deal with than Mouser.

 

oh, heres an illustrated howto on removing the clustger assembly...
https://www.brickboard.com/FAQ/700-9...ClusterRemoval

this applies to 1991-1992 740 too, but NOT to older 740's, they are different.