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The mkiv Supra Owners Club

Odometer intermittency


QSC

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Wonder if anyone has any suggestions - odometer goes on and off intermittently, and just before the MOT is due too. It still counts the miles, but it won't stay on for long at all, doesn't seem to be any pattern to it ?

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Does the ECU log any error codes (and make sure the orange engine light bulb works)? The reason I ask this is because the odo is upstream from the ECU. The odo takes the speed signal as an input, processes it a bit, and spits it back out towards the ECU. If there was a problem with the speed signal within the odo then the ECU would probably report a code 42. If no code 42 is reported then I would suspect the display part of the odo circuit board: inspect it for dry solder joints, broken tracks, burns etc but if you can't find any then I'd suggest a replacement odometer.

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Yep - showing code 42 - I've already had the odo board out though & can't see anything wrong with any of the solder joints, it all looks pretty good - I could redo the wiring connection on the wiring plug, but other than that it all looks fine.

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Code 42 will mean there's a problem somewhere along the speed-signal stream. It starts at the speed sensor, goes to the speedo (does this work reliably?), then goes to the odo, then to the ECU.

 

If you have a speed converter fitted, check that all the joints are soldered properly.

 

The buffering circuit within the odo circuit board is known to give up the ghost. You can try joining the odo speed signal input to the odo speed signal output, thereby bypassing the buffer. It might or might not work but if you've exhausted other options and are thinking of getting a replacement odo anyway then you could try it. I'm pushed for time right now but I can try to look up details later...

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