I have viewed all the links on how to remove the dash and instrument cluster etc...... and know what small plastic gear I need to replace to fix my non working odometer, I am just not clear on the trip/odometer, do they both run off the same gear or separate? Thanks for any guidance, none of the videos or links were very clear about the trip meter.........

 

The same gear fixed mine.

Replace both gears.

 

That's what I am referring to, FCP shows one gear for the odometer, is there a separate gear for the trip meter?

Volvo Odometer Gear (850) - Odometer Gears Limited 850GEAR | FCP Euro

 

The small gear is powered by the small electric motor from the cluster. The gear itself powers a bigger gear which turns both odometer and trip meter. So when the small gear fails the bigger one also stops and bot odometer and trip fail.

Take care when replacing that you take out all the "remains" of the old gear otherwise the new one will get blocked and you will need to replace it again

If your car is MY95 or older (has the diagnose box and no OBD port) you can test after the replacement if it works without driving the car as follows:

- put the diagnose lead in the A7 hole
- ignition on
- press 3 times on the button at the diagnose box.

All gauges will go in test mode (speedometer and engine speed stay at 12 o'clock), fuel gauge in the middle, water temperature goes up before the red area
Here comes the interesting part:
The odometer and trip count 500m or in your case half a mile . After the cycle is completed all gauges return to the resting position. You can repeat the procedure as often as you like.

Also if your car was driven a lot with the broken gear you might want to correct the odometer reading which is fairly easy when you have the part in your hand.
Use again the diagnose box to read off the mileage from the cluster .
Press out the steel axle where the odomter barrels are on and put the right combination back.
Before putting it all back together make sure that the barrels rotate freely otherwise the motor will not have the power to turn the mileage barrels.

 

There are two gears that turn against each other to record mileage. If either of the two gears go bad, both the regular and trip odometer stop. IMHO, always replace both.

 

Thank you gentlemen, exact info I needed, I appreciate it.....

 

For our 1996 850 we fixed our odometer using the tiny $25 cog, got the true mileage from the OBDii with an ELM327, and updated the odometer by directing compressed air on the appropriate wheel, motor off. Spins clean and fast.

 

My mechanic, that I really trust, tried to fix the odometer and failed.
A then got a used, guaranteed one, that my mechanic put in. It did not work and I returned it. Then, I had a friend, a very good mechanic, try to repair them using
parts from both. Now, neither the odometer nor speedometer work.
Thus, spending money to have someone install a something that doesn't work, deal, with returning etc, is a pain. Does anyone know where I can get a used, or rebuilt, odometer, speedometer that is guaranteed?

 

Are you saying that they tried to FIX it but did not replace the gears and instead attempted to swap parts around? Why?

I am not aware of a speedo gear replacement service. Your probably looking at purchasing a cluster off eBay which you just dont know what your going to get. Have you tried a wrecker?

 

Yes, I tried a wrecker. When it did not work he did take it back.
He also told me there is no way to test a used part. i find that hard to believe.
That is, how would you test a used speedometer/odometer when it is out of the car to see if it works.
BTW, the original attempt was with replacing new gears, the second attempt was to swap parts that look ok. Right now, I am afraid to do anything without knowing this attempt will work. The new part is $600 + installation .

 

the odometer gear doesn't impact the speedo - the typical failure is on the small plastic wheel which can lose a tooth. If you don't have your speedo or gauges etc, then I'd suspect one of the connectors on the back of the cluster didn't get set correctly during the reinstall. I've done this 3 times in 850s all with no issues. It takes about 30 minutes to pull the cluster out (once you know where the hidden screw is) - and then you can work on the cluster on a bench (T8 torx bit required). Accessing the gears requires you to pull the needles off the gauges to remove the face plate so I'm wondering if the tech messed up the speedo replacing the needle. I have a spare cluster here at the house that was in a 95 850T that was swapped out so I know you can swap components (no programming etc).

 

Thank you.

 

I have also seen the actual needle coming loose from the peg (its just pressed on) so the peg was moving but the needle was not. This was my turbo needle mind you so I dont know if its the same for the speedo.

 

Thank you.

 

What would cause the odometer to tick off ~3 miles for every 1 mile driven? The car I am looking at/planning to purchase this weekend has this issue, and from what I gather it developed after the PO replaced the dash...I'm familiar with the ODO not working because of stripped gears (my 97 base had this problem) but never heard of the gears causing it to read more miles than driven...

 

What worked before?

Does neither mechanic have a OBDII scanner that can read car speed? If not, I would recommend finding a mechanic ones that do.

Don't high jack a post, make your own thread.

 

The speedometer worked, but odometer did not. Now nothing.
Awesome, no one seemed to know there was a way to test the odo/spedo with
OBDII. I will bring that up to them. Thank you. My 88 is now an antique so getting
everything working is important.

 

Another question about OBDII: does it also check odometer reading?

 

Wow, really? Nice to know the people around here are friendly and helpful when you need an answer to a related question...

 

Truly, Despite knowing knowledgeable mechanics who have helped me keep my Volvos running beautifully, THEY did not have this info.
Thank you.