Piaggio X9 Evolution 250 scooter incorrect mileage odometer reading

A Piaggio X9 scooter that had electrical problems after being in the rain.

Water had got into the clocks and the electrics were not happy, many dash lights randomly lit.

After drying out, the scooter was all ok except that the distance / mileage was reading 99998 km or 62498 m (bike had been set to miles but had reverted to km).

This was not good ! service history and re sale is hurt with the mileage so wrong, also it wouldnt increment ! so basically broken.

A google showed its not uncommon, water gets in at the edges of the push buttons, I found a forum post that recommended sealing the buttons and putting bags of moisture absorbing gel inside the clocks.

Surprise surprise the clocks were opened to find that the buttons had been sealed and little bags of gel put inside already by whoever had the same problem last !

The sealent had gone off / was not the correct type and had let water back in.

I also found people on the web talking about the mileage going wrong, reading 99998. I figured the mileage had got corrupted.

The mileage is stored in a serail eprom 24c02

I removed the chip and read its contents, the chip read fine and comparing the contents to a good dump I found on a greek forum, it looked valid.

This was the first thing that made me think that the chip and contents were fine, just that maybe the MCU could not read it at boot up.

Here is how I powere the clocks on the bench.

I checked that the serial eprom was powering up by checking continuity to the supply rails, they were ok.

I checked continuity of the data pin to the MCU,this was present.

I checked continuity of the serial data clock pin to the MCU and could find no connection, this did not seem right !

The data pin also connected to a large pad on the edge of the pcb, presumably for factory programming, sure enough the clock pin did not go to any of these pads, however one of the MCU pins did.

I fitted a link from the eprom clock pin to this pad and.....

Result, the correct original mileage now reading from the eprom at power on.

It looks like the link for this track in the multi layer PCB had gone.

The clocks were re sealed and re fitted to the bike, all reported to work ok, mileage reading, incrementing and storing ok.