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3 dead odometers but speedo is OK

apollo13

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Odometer stopped a few weeks ago. I got an instrument cluster from wreckers, and swapped it, but no workee. The speedo worked on both clusters. So I complained to the wrecker, but he responded that they check everything before putting it on the shelf. Well I don't know how they could check odometer in an immobile damaged car. Eventually I borrowed a third instrument cluster, which I know works. Guess what? Odometer still moves not! All 3 clusters are the same: V6 level 2. I do not get error code 24 for bad vehicle speed sensor. Also gear shifting seemed quite normal. I start to wonder if I have a weak pulse that drives the speedo, but not the stepper motor in the odometer. I checked the printed circuit tracks on the cluster. There are several that seem relevant: SPEED SIGNAL, 10 PULSE, 2 PULSE and PULSE GND. None are damaged. Also I dismantled the second cluster, and there were no broken gears in the odometer.
So what are these signals 10 PULSE and 2 PULSE? Is one for speedo and the other for odometer?
I have the workshop manual on CDROM, but that does not include the electrical diagrams.
 

88GreenVN

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The odo counts kms from the same pulse so it will be gammed gear of busted tooth. If the sun gear has been put in upside down the odo will fail.

With the speedo head out of the cluster see if you can spin the kms over by hand - all should be turn over smoothly. If notchy it will stick at this point in the car.
 

apollo13

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Looks like I got 3 bad clusters! I took the third one to a VDO service shop and they said a voltage regulator was burnt out. I have to return that to it's owner, who swears it was working. It was in a car that broke down 6 months ago. The original odometer did have the broken cog. I got a replacement to fix that up. Do not know the problem with second - presumably electronic component as well. At least I have a supply of spare bulbs now.
As for the two PULSE lines, the speed sensor gives 10 pulses per revolution. This is divided by 5 so that is presumably the "2 PULSE" signal. I don't know where the division is done (in speedo or PCM).
 
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