aytchkay

I have a 9-speed Shimano group with Flight Deck. After 7 years, I could no longer change the display on the computer head. I figured it was the wiring harness so I bought a new one and installed it - voila! it worked! well, almost.
Now the gear diagram (ovals) shows the chainring changes but not the cassette changes.
Once in awhile it will change, but it mostly stays in one place - which is usually the 2nd largest cog.
Does anyone know what I should check for this problem? All changes with each 'button' work fine. I imagine it's in the right lever since that controls the rear derailleur.
I have SC-6502 computer head, and SM-6500 harness - which is the model with one button on each STI lever.

HELP!!!!

Chris_W

Check the connections inside your right-hand lever. The lever needs to tell the computer which rear cog you are in, and the signal isn't getting through. Take the part that has the button on it out of the lever, clean everything up behind it, especially the connector, and the connector on the button unit, then reinstall. If that doesn't work, then you'll probably need a new lever, new nine-speed stuff is hard to find (except Tiagra and below), but try eBay. Alternatively, if you know someone who has a 9-speed lever but who doesn't use flight deck, then see if you can switch levers with them.

aytchkay

I fixed it by installing a tiny "shim" behind the contact in the right lever.

I looked at the 'manual' that came with the harness and they mention that if the gear indicator is not working right, to put these shims behind the contact assembly - they included 4 little squares of sticky-back material of which I installed ONE, and now it works just fine...
So if anyone else is having this problem - this is one solution!!