I have a 96 Volvo 850 wagon and the speedometer wants to work every once in awhile. What could this be?

It's impossible for anyone here to give an estimate because rates and parts availability vary from state to state. I'd call your local Volvo dealer parts department to get an idea of the parts costs or even if they can find one. You may have a better chance of locating the parts in a junk yard.

alot of problems stem from a worn out ignition tumbler, if you turn your key on is there play to wiggle it forward and back a little? its the culprit for so many issues believe it or not, Ive had my 850 turbo wagon for 15 years and know her like a book. mine does this and after i restart it its fine. my odometer stopped working and Its an easy but timely fix so i just left it as the service light comes on for service at the right mileage. anyway, if tumbler is good then your cable is going bad.

This is a common problem with 850s. The speedometer is driven electrically, while the odometer is mechanical.

There's a tiny little gear inside the odometer that runs it from a motor; it's no longer tied directly to a speedometer cable like older models. What happens is the gear gets old and brittle and loses teeth, at which point it can no longer turn the odometer.

My wife's '96 850 had the same issue when I got it, and a little internet research turned up the answer above. There are companies that make replacement gears you can buy fairly cheaply, but it does require a fair amount of mechanical aptitude to pull the instrument panel and disassemble the speedometer assembly.

One note of caution that I learned the hard way: you have to take the front cover off the instrument panel, exposing all of the gauges. Be very careful not to disturb the position of those little needles; I ended up messing up the gas gauge, speedometer and temperature gauge, and it took a lot of trial and error to get them put back in so they showed the right readings.

If I recall correctly, I found instructions for doing the gear replacement online, but it's been so long that I don't have the web page(s) I found any more. A lot of times the manufacturer of the replacement gears have instructions on their web sites.

IPD USA sells them and has instructions.

850 Odometer Gear

Front oxygen sensor code. Check the vacuum line to the fuel pressure regulator and make sure it is ok before you replace the sensor. Any vacuum leak can also cause the code.

i think its a collision because i have the 96 850 turbo wagon and have had her up to 130 and nothing happened

You can check 2 things. 1., have someone in the car to turn the key to the start position. Tap the starter with a small hammer and see if it cranks. If it does, replace the starter. 2., have the battery tested as well as the connections to the battery. Corrosion builds and can cause heavy resistance to heavy loads(like starting). These are the 2 most likely causes. Let me know if you need further assistance.

Two questions: Is your odometer working? If not then it's probably a broken gear by the stepper motor that Emissionwiz mentioned. Is your ABS and/or TRACS light on intermittently or constantly. If so that is a common sign your ABS control module has gone or is going bad. This usually happens before the speedometer starts acting up. Either one of these will start intermittently and finally end up with the speedometer not functioning at all, and both are pretty common failures with this model.

The heater core on your Volvo is an easy fix. The dash does not need to come out. You remove 6 screws from the center console, pull that out of the way, pull back the carpet and there she is. A couple more screws, a tug to the back to remove the bad core and you replace in reverse. Put down a plastic bag or catch-can to get whatever coolant comes out when the core is removed. I thought I was in for an expensive repair until I researched and saw how easy the job was.

Ultimately, Stick to the Above Diagnosis. You have already Discovered what the Problem is. DO NOT let the Mechanic repair all this other Stuff that May Come up until after the Ignition has been Replaced. The Ignition being Replaced should solve these Problems without any added Repairs unless they are Small ones. Should not Cost you all that Much either. Please Rate My Response! Thanks!

Mark,

As long as you have the instructions to replace the speeometer drive gear go ahead, and do it.

One BIG question I have for you....how do you know that the mileage is not way over what you've been told?...

small tip for the future.......if you ever look at another car for anybody, and the speedometer doesn't work...pass up the car..there is always another one down the road waiting for you.

Hopefully this will help you, and thanks for letting us at FixYa.com help out...happy New Year