OK, sorry if this has been discussed before ... I searched, but most of the results had to do with a normal tach install.

I have a 88 245. A little while back, I successfully installed a 80mm tach + 52mm clock without incident. There was an extra red+white wire back there, and the job was a piece of cake. After installing the new tach, I had an extra, working 80mm clock.

Now, my mother's 90 244 had a broken clock for many years. I decided to give her my old one (despite the matte/glossy finish difference, a working clock is better than not). So I freed the instrument cluster, disconnected the wires, and wrote down their colors/locations like the amateur I am. Then I noticed something strange. She did have a red+white wire behind her cluster, but it had been plugged in, behind the speedo (to the top of that two-pronged metal plug)! Her extra/unconnected wire is yellow! In my 88, the wire plugged in to that same spot was blue, but otherwise looked the same as her loose yellow wire.

So, is this what I think it is ... did someone at some point plug the wrong wire in back of her speedo? If so, what might have been the effects (is this why, for example, her rear fog lights just don't work, despite new bulbs and fuse)? Should I switch the wires so that the red+white is disconnected?

Thanks!