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-   -   Legendary odometer problems. (https://www.volvoforums.org.uk/showthread.php?t=310945)

natmargetts Oct 17th, 2020 17:12

Legendary odometer problems.
 
Evening all, we return to a case of yet another person suffering from odometer problems.

Diagnosis:
Speedo works
Replaced the gear that always breaks with a new one
Still not counting


I have read that it could be bad capacitors, or a cold solder joint that needs to be reflowed. I just wanted to confirm that I'm barking up the right tree here?

Cheers

natmargetts Oct 17th, 2020 17:13

Oh- It is off a 1990 740GL and is the VDO cluster also

bob12 Oct 17th, 2020 19:28

Clearly the signal is getting through from the rear diff sender as the speedo is working. Have you got abs but doubt it as it was optional extra?

Assume your speedo has the pin connector to the white back board/blue circuitry as it's 1990. Make sure those stupid pin connectors on the speedo unit are all slotted dead straight and not bent to the side - seems unlikely as speedo working. It's also unlikely that a VDO capacitor has gone down but could be a possibility. It's the big age related problem with Yazaki's.

Did you double check and checked again that one of the ultra small cogs off the stripped drive gear wheel is not stuck somewhere in the drive mechanism. They have a habit of doing that.

You could re-flow the internal pcb but, I would first take it to pieces again (!!!!) and make sure the stepping motor is ultra free to turn as well the drive cogs to the mechanical milo cogs. Make sure not to tighten the pcb down too tightly as pressure here can affect the stepping motor.

I had experienced all these problems/niggles until by sheer chance I acquired a cluster with a VDO speedo made by VDO Australia at the end of VDO's then existence. After replacing the cog it's been a 'Bute'!

Bob :)

Laird Scooby Oct 17th, 2020 20:20

Quote:

Originally Posted by natmargetts (Post 2673895)
Evening all, we return to a case of yet another person suffering from odometer problems.

Diagnosis:
Speedo works
Replaced the gear that always breaks with a new one
Still not counting


I have read that it could be bad capacitors, or a cold solder joint that needs to be reflowed. I just wanted to confirm that I'm barking up the right tree here?

Cheers

Barking? Yes, probably! :tongwink:

Joking aside, yes, you're on the right track but 1990 would have been the very, very last of the VDOs, if it wasn't already Yazaki. Are you 100% sure you've identified it correctly? Some of the guides to identification are a bit ambiguous!

Hopefully Bob (bob12) will be along at some point, he has an amazing knowledge of the clusters, especially the VDO ones so can give you a few more pointers than i can.

natmargetts Oct 17th, 2020 22:00

https://i.imgur.com/VU8I2Cb.jpg
These are the gauges, I just assumed that you use the trip counter number separation to work out which it is...

Not sure if it means anything, but on the speedo face there is the number 0020 at the very bottom right (not visible until the front fascia has been removed.

bob- I will give wiggling things about a go, however if I can't work it out I may have to make a visit if that's ok as woking isn't too far!

Laird Scooby Oct 17th, 2020 22:24

You assumed correctly on the identification. :thumbs_up:

http://www.volvotips.com/index.php/7...740-tripmeter/

http://www.volvotips.com/wp-content/...ecognition.jpg

The image and link to identifying. Once you've fixed it, a good way to avoid it failing again is to only reset the tripmeter when stationary, someone found resetting it while moving was a primary cause of breaking the gear wheels inside.

natmargetts Oct 18th, 2020 00:15

Hi Dave-

I've already followed that guide and installed a new plastic gear, yet it still does not work- this is why I'm asking about further causes as I'm at a loss :(

Laird Scooby Oct 18th, 2020 00:58

Thanks to my internet being slow tonight, i hadn't seen Bobs erlier reply until a short while ago but basically check for pieces of the old broken gear, check the mechanism is free to run, that the reset button hasn't stuck and so on. It could be a duff cap in there but that's more likely on the Yazaki units.

It might be better in the long run to find another working instrument cluster from the same year car, that's what i resorted to on my last 740GLE. Trouble is they're expensive now, back then i picked up a cluster for 30, now they're 3 times that! :eek:

natmargetts Oct 18th, 2020 11:45

Thankfully I do have a couple of spare VDO units sat in the garage- I was just hoping to fix this one as being a young driver (20) insurance are anal about checking everything on the car so I don't want to have to wind an extra 140,000 miles onto the replacement - booooring!

Really appreciate your help though! Ill get it out again today and recheck the mechanism and make sure that the stepper motor works okay!

Laird Scooby Oct 18th, 2020 13:08

Quote:

Originally Posted by natmargetts (Post 2674029)
Thankfully I do have a couple of spare VDO units sat in the garage- I was just hoping to fix this one as being a young driver (20) insurance are anal about checking everything on the car so I don't want to have to wind an extra 140,000 miles onto the replacement - booooring!

Really appreciate your help though! Ill get it out again today and recheck the mechanism and make sure that the stepper motor works okay!

There is a much simpler way!

https://i.postimg.cc/mrTRF3Pt/2012-1...-33-14-431.jpg

https://i.postimg.cc/W1GT3YbB/2012-1...-40-03-632.jpg

Those photos were taken ~7 minutes apart, before and after swapping the old dead speedo/odo with 182k on it for a working unit with 32k on it. Not done for any financial gain so it's fully legal, photos were kept as proof of the old mileage and the mileage when fitted and i would think if your insurers have half a brain cell between them all will see you're taking a proactive approach to ensuring you don't go over your insured mileage each year. Granted the starting point might be different but by photo evidence, you can prove the old wasn't moving and the new does. Problem solved and it takes seconds to do it! :thumbs_up:


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