Rick: I think he is asking if the new (used) odometer (not Speedo) will screw-up the mileage in the computer. The answer is no. The odometer is a mechanical device that works off of the computer/electrical pulses.

Mileage from your new (used) odometer and computer mileage do not match, and will stay unmatched, unless you want to fix it, and you should.

Winding or unwinding the odometer gear though is very simple with a drill and rubber hose.

 

So, if I replace the ECU with one from IPD or somewhere to boost my HP, will my mileage checker still work through the OBD-I port?

I just checked mine that stopped at 102,842 and the port says it has 110,048. Can't believe I drove over 7,000 miles that fast (less than 2 months). I had the key in the run position.

So, is the mileage kept in the ECU? Post 13 indicates it is not. I read something over on Matt's site and it indicates the cluster keeps it. However, if you crank it up yourself, it will keep the newly kept mileage. So, if you change the cluster, put what the old cluster indicated and it will report that. Go figure.

 

Here are my printable PDF instructions. A little different so the mileage is given in order.
http://www.matthewsvolvosite.com/for...e.php?id=12687

 

This doesn't work on my 95 or my housemates 93 model, I would assume then, that it only work with the VDO cluster, as both of ours are yazaki clusters. Yazaki clusters were fitted to about 90% of the 850's here in australia, unless you ordered the trip computer from new, or it was a turbo model, then you got VDO

 

Oh, does any of the OBD-1 mileage checker stuff work for the Yazaki clusters?

 

Well I know the cluster self test does not work on the yazaki clusters either, so I wasn't surprised when the mileage didn't work. I can understand why Volvo put the cheaper clusters in here. They have to cut costs somehow. These were $55,000 for a 1994 GLT new when you could get a Magna (diamante) for $23,000 or a Holden Commodore for about $29,000 new.

A 1988 Volvo 760 GLE was $86,000 new here in Australia......they weren't that popular.

 

If you have a newer model, 1996+, this thread may help you:
https://volvoforums.com/forum/volvo-...ars-ago-64875/

 

Here is a video:

 

Is there any way that dealer service (or my or dealer accidental pressing of buttons?) could reset the mileage recorded in the cluster on '93 850?
I have owned a US model '93 GLT from new. I bought a new odo drive gear and am about to install it so wanted to see what is the discrepancy between odo display and actual recorded mileage where odo stopped at 133 thousand. Using the A7 method with 111 and 112 presses comes up consistently with 101 thousand - perhaps some 40 thousand miles less than actual.
Vehicle did visit dealer around 39000 miles for issues with climate control and gauges, bill does not show work on cluster specifically but does say "repaired frayed dash harness" - is there some way that the stored mileage could have been reset to much lower than the odometer displayed mileage?
Bottom line, I'm perplexed how it could show so many lower actual miles in the cluster than the stopped odo display. Ideas?

 

The link to this post in the stickied diy-post is dead

 

which link is broken? I clicked on the link on RSPI's 4-9-2012 post in this thread and was able to download the PDF from the matthews site.

 

On the post: https://volvoforums.com/forum/volvo-...repairs-26114/

The link under the heading "Odometer Broken, How To Get Actual Mileage for 93-95 850 Volvo (OBD-I Port)" points to https://volvoforums.com/forum/m_145069/tm.htm when it should point to https://volvoforums.com/forum/volvo-...0-volvo-27012/ (this post)

 

Thanks Caltemus. Links should now be updated.

 

Thanks for the info :thumbsup: Came in handy with the new 850T. Odo reads 274xxx and the flash codes come out to just under 218k, which is what the previous owner said the car had. Now to replace the odo gears and figure out why she clicks off 3 miles to every 1 driven...

Edit: odd question, but I found today that I have one of the oddball 95's (mfg date 10/94) that has an OBDII port under the coin tray...Is it possible to utilize that port to pull miles instead of reading flash codes?

 

my understanding its really an "OBD-1A" port (yes I have a 95 with the port under the coin tray). I came across a schematic for making your own "reader" which essentially uses a button switch and an LED to do what the diagnostics port's button and LED does. I've never tried to put an OBD2 reader into that... curious if it does as well.

 

I was searching for what to do when the red LED won't come on using the on-board code reader. As it turns out I was able to use an LED test light by attaching the alligator clip to a good ground (the engine hoist bar works well) and placing the sharp end between the resistor and the LED light. For some reason the car's LED light wouldn't light up when using it to find the car's actual mileage so I went to P A P and bought two of the code reader enunciators (for lack of a better term). They didn't work either. The LED test light worked just fine using the method mentioned in the above post. I found that my '94 Volvo 850 turbo station wagon had 286,221miles on it. Luckily the engine had already been replaced with a fine running one with likely much lower miles.

 

I actually came across a thread a while back on how to make a home made code reader using the OBD port (the 850Ts have one under the coin tray) using an LED and button switch from Radio Shack.