Sages,

A few weeks ago I posted about fixing my intermittent odometer and they having new issues.

Well the odometer is still intermittent. It will not work when it is cold out. Yesterday it was in the 30's and did not work. Once the car warmed up it then started working. Ugh!

I have it out at the moment and can not find any cold solder joints.

What are my options? Where should I be looking at or look next??

Can I swap in a K10042 for a K9800?? Are they interchangeable???

Should I be looking at the rear diff???


Kind regards on this turkey day,

Matt

failing OD motor, OD gear loose on shaft

Sages,

So the intermittent odometer has been fixed or shall I say the root cause of the problem has been discovered.

This morning after careful observation of the LARGE gear under a microscope I was able to see two of the teeth that were broken and right next to each other so I will now be ordering a replacement for this and in the mean time I will put in one from one of my donor clusters just so I can get it working again.

Thanks AGAIN for all of your help and patience with me as I slowly work through these issues.

Regards,

Matt

I've never seen a damaged carrier gear. Always wondered why it is pushed on us by the gear vendors. Perhaps they are getting broken by forced trip resets? I wonder now what is the root root cause. I am assuming you are referring to this:


--
Art Benstein near Baltimore

When you dream in color, it's a pigment of your imagination.

Art,

Yes, I am referring to the carrier gear. Though the main assembly is plastic, the gear it self is vinyl I believe and has gotten soft.

When I pressed on it under the scope I could see that it was not only soft but mushy. The gear also had some sort of wax on it. Not sure where that came from.

So for now I'm going to replace it with one from my vast collection of clusters (2) and I've also ordered a replacement from FCP which should be here by the end of the week. Before I put the "new" used one in I'll check it out tomorrow to check it for cracks as well and if there is any substance on it I'll clean it with some rubbing alcohol before installing it tomorrow night.

As for the root root cause, unknown, but the car does have 328K + miles on it and well nothing lasts forever.

Thanks again for your help and for your knowledge that you have on cleanflametrap.com. It came in handy when debugging the circuit board.

Regards,

Matt

believe it to be the motor. I am currently diagnosing it and the signal out of it (pins 2 & 18) are crappy compared to another known good one.

Will post later this week when I've finished my testing.

If you are observing the waveform on the motor pins, said crappiness may easily be the result of an open circuit there. The motor itself is just a hunk of wire wrapped around a stator made of iron -- not much to go wrong electrically except a broken wire. That's easy to have happen during a gear replacement.

Replacing the motor is dicey because it is located (and somewhat secured) to the circuit board by plastic pins which are then melted over in production. It is a nice challenge for the education but not a practical service procedure, with the supply of junkyard parts still available.
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Art Benstein near Baltimore

She criticized my apartment, so I knocked her flat.

In the 15+ years we have had our ‘89 wagon, Ive gone thru about 5-6 speedo‘s, mainly due to the odo and trip meter "malfunctioning".. One thing I learned is to keep my finger off the trip reset button, seems to help, so far.

Few days ago tho, regardless of my caution, the odo/trip meter stopped working, again. I called Dave, he always has a supply of speedos on hand, but we went thru 4, yes 4, before finally found one that works perfectly, so far. He has no way to test them other than installing them and running them. One thing he does tho, he never picks one up that the trip meter is already set on zero, that almost always is a sign the trip was reset and it had stopped working.

THE COMPONENTS OF USED ITEMS ARE GETTING OLDER, STRESS CRACKS, AGE CRACKS, ETC.(HMM, SOUNDS LIKE ME). I DON’T HAVE MUCH ADVICE, BUT KEEP YOUR FINGER OFF THE TRIP RESET BUTTON, OR IF YOU MUST, DO IT ONLY WHILE TOTALLY STOPPED AND PRESS IT GENTLY. GOOD LUCK.

Wow. All that in one car??

I don't know to which Dave you are referring, but the Dave I know has the test lashup. We worked together on these years ago.

I feel your pain and when something is not well understood, I want to understand it better. That's why I dig for the specifics, and not a general criticism usually directed at VDO.

So far in my experience, the only problems with the speedometer gauge I have found NOT to be directly attributable to repair attempts, are with the 25 tooth gear becoming mushy and the plastic post retaining the service reminder counter spring. I could easily learn to add the carrier gear to this list; it just hasn't been my experience yet.

Although the solder crack defects are exacerbated by handling when attempting to repair the gauges, knowing they are potentially a problem in every old unit, responsible repair procedures should include reflowing them.

Some of the problems WE add are:

1) Not making notes of where the wires go (specifically putting the tach lead on the VSS tab.)

2) Stressing the motor-to-circuit board mounting in removing or especially replacing the odo/speedo board, jamming the rotor.

3) Failing to find each part of a broken gear.

4) Allowing magnetic particles from a work area (we used to call them iron filings) to enter the meter magnet gap.

5) Poor soldering.


Yes, I agree the mushy gear is more likely to quit gearing when the trip reset is pushed, but examining the mechanics, I do not believe the trip reset needs to be avoided after replacing with a NEW (and strong) 25-tooth gear.

We have 5 240s with electronic speedometers, and we use our trip resets. I reset them stopped or moving -- because I can observe the function and see that this is all anecdote centered on a soft gear. One big lesson I learned is there's only more experience to be gained by attempting to repair these without using a newly made gear.
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Art Benstein near Baltimore

Reading whilst sunbathing makes you well-red.

First-the “Dave” im referring to: Dave Hoffman, older gentleman, SF BAY area, been working on Volvos for years. He is mobile, no actual “shop”. Very honest, does good work, for the work he can do. Of course he does not have some “vital equipment” to do some things, such as alignments etc. I have others I also trust for certain things.

You say “all that in one car“-?- or was that sarcasm not really looking for a reply?? Yet I reply, yes, all that. Had the brick for right around 17 years now. Started the folder of records right at that time etc. You would be surprised how thick just that one folder is. The covers are “writeable on” also, and all the covers are covered in facts, dates, etc.

Records of repairs, oil changes, tune ups, new tires, even flats fixed, you name it. I’ve been very meticulous. The previous owner inspired me. At the time we were aiming to buy the brick, I sat in his living room going thru his records and receipts. Very inspiring. Even if we never sell the brick, I enjoy keep track of it all. The last “repair” I listed was replacing ALL the brakes with “new” calipers, pads, rotors, brake lines, fluid of course. All the receipts, so just in case I did put up the ‘B’ for sale, its all there.

Due for an another oil change in a month, had to calculate that with the change in the odo. Oh, I found when he replaced all the tailgate wiring harness stuff. Fun to look back, I had forgotten quite a bit. Im also impressed how Dave can understand and follow wiring schematics, that’s all “greek” to me.

Glad there are others smarter than I, in certain areas, well, at my age that entails just about everything now-Haha. Hey, I can still boil a 3 minute egg in 4 minutes :o(. Oh and I can wash and wax the brick!! The one good thing I’ve been told is I am smart enough to know how dumb I am ( I think-?) Haha.

Im glad you count the teeth on the gears, someone has to do it I guess. That shows me once again just how smart some are and how dumb I am, I guess. :oÞ~~~

I wasn't worried about your records. I know mine are in enough disarray, I could not hope to give advice to anyone else in that area.

But my "??" indicating surprise is finding you had a repair done so many times to the same car. But now I understand. They were not really repairs, just swaps of used parts. We've had our '89 wagon since 2000. A tad less experience than you with yours. It has the original speedometer. Also repaired more than once, as I learned the truth about using the original gears we describe as 25-tooth in order to identify them. If you look at these, and exercise your mind counting teeth, you will find a few missing. :)

I would only offer the advice you have -- about not using the trip reset -- if the repairs were not made, but the used gauges swapped in instead. That was the gist of my point.



Smart is enjoying the satisfaction of driving a 25-year old brick for 15 years, whether you make the repairs or someone who has earned your trust does them. Well, I think so, anyway. Probably not too many contrary opinions to be found on that subject here on this forum.
--
Art Benstein near Baltimore

When two egotists meet, it's an I for an I.

Just a little notation: I consider swapping out parts to be a repair in a sense. It "repairs" the problem, maybe not the actual part. I do see your point tho.

Swapping new for old is a swap also I guess, not just swapping an old one that doesn't work with a used one that does work. Hey, fixing a flat is a true repair----isn't it?

My wife says I need my brain repaired----maybe swapped out?? Reminds me of Franken------.

Just a little notation: I consider swapping out parts to be a repair in a sense. It "repairs" the problem, maybe not the actual part. I do see your point tho.

Swapping new for old is a swap also I guess, not just swapping an old one that doesn't work with a used one that does work. Hey, fixing a flat is a true repair----isn't it?

My wife says I need my brain repaired----maybe swapped out?? Reminds me of Franken------.

Being as many of us, most of us, have a few spares "on the shelf" even duplicates of things we've not had go bad in 10 years, I wonder how many have a set of gears on the shelf "just in case". I confess that I repaired mine by swapping in a complete correctly numbered instrument panel. The extra 10k miles on it, up to 70k, meant it probably corrected the mileage I'd lost. Was intermittent when I bought the car, a '92 SE wagon.

Anthony,

Thanks for the advice.

The way that I tested out my speedo was by using Art's information located here:

http://cleanflametrap.com/speedo.html

Unless you have access to the equipment that Art is using you won't be able to diagnose the device down to the level that I did, but you would be able to take the odometer/speedometer motor board off of the side of the speedometer and see the little brown winding gear spin.

If the brown winding gear is spinning then it is either one or both of your plastic wheels that will need to be replaced to get it back up and running.

I ordered the large gear yesterday and it should be here by this weekend. I also went through what parts I had at home and was able to find a large gear that was not broken. The other one I had was and is not resting comfortably in the trash can.

So a question I have for you is how do you know the mileage of your car if you keep on swapping out speedometers??? Just curious that's all or do you not care??

Any ways, thanks again for the advice and have a great day.

Regards,

Matt

It's a reasonable question-how do I keep track of the "real" mileage"? Well. it’s a little difficult but I do have a method: Ever since the first time I swapped out an odo, I write down the mileage at the time in a folder where I keep most all my receipts, and I'll tell you it's a THICK folder. I write down the mileage of the one that is 'deceased" on the inside cover of the folder, including the date. I also write down the mileage showing on the "new" one.

From there its fairly easy to keep track of the actual mileage. Im pretty close I'm sure, even tho it may take a few days to get the "new" one installed. I'm not out to "trick" anyone about the "real" mileage if and when I should sell the brick. At this point actual mileage is right at 355k-and yes the brick is doing very well. The mileage showing on this latest swap is just over 178k, so I make note, write it down and there you go.

As I said, if and when I were to sell it, the "new" owner will see all this. Ive kept pretty accurate records of "this and that", records of oil changes, tune-ups, tires and repairs along with "tons" of receipts. The previous owner also kept great detailed reciepts. I do keep records of my mileage(mpg) also.

I meant to say 2 & 18, not 2 & 8.

Art,

This morning I looked at the defective one and the signal coming out of pins 2 & 8 was not a nice square wave. The "high" part of the square wave was continuously being broken up so that it was not a continuous signal, where as the one from the Sedan was nice, clean and smooth.

Tomorrow I'm going to stick the rotating motor part in as I did not bring that with me today. That will really tell me what is going on or in this case NOT.

I'll let you know tomorrow.

Regards,

Matt

Hi Matt,

I didn't look up the pin numbers but assumed you are talking about the two which drive the stepper motor. They are the open collector (sink to ground) outputs, so if you have hash on the high side of both phases of the waveform that would be consistent with a poor connection (open circuit) in the path from the power supply to the motor's common pin, where the windings are joined.

A poor solder or broken (stressed) motor winding wire would do that, as would a crack in the foil. Move your scope probe to this terminal and toward battery source to find where the voltage drop is occurring. Having the magnetic load of the rotor would have but a subtle effect on the waveform at the driver terminals.


--
Art Benstein near Baltimore

Without geometry, life is pointless.