The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: oz_johnno on March 20, 2012, 01:22:37 AM

Title: aww crap, help needed with tacho connec
Post by: oz_johnno on March 20, 2012, 01:22:37 AM

howdi,
I have been having a look around beryl to see what needs doing when i noticed that a couple of the idiot lights in the instrument panel are not working.  So I removes the panel and pull it apart, but when I take out the PCB to clean the contacts (lots of corrosion there) I disconnected the tacho without noting which way round the wires were connected.  >:(

the situation

(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi1197.photobucket.com%2Falbums%2Faa431%2Fozjohnno%2FIMAG0398.jpg&hash=01da9a2966f406327eaa95741819534c54690c50)

so now I have a brown wire, a red wire and a green wire to reconnect to the PCB, but have ho idea as to which way round they go ! (please note that there are 3 spade terminals on the LHS of the T shaped PCB)

Help please

OZ

Title: Re: aww crap, help needed with tacho connec
Post by: tvrla on March 20, 2012, 08:19:22 AM

I'm not in the shop right now, so can't look at my notes. You'd think I'd remember this having just worked on a couple of these recently.

But I do recall that the green (signal) is in the middle. I just can't recall if the brown or the red are on top (positioned like a T).

I checked the wiring diagram and most of them are pretty confusing if they have the data at all. Some of these wiring diagrams are next to worthless and think they're intended to confuse us.

Anyway, the hot (red) is attached to pin #8, signal is green to pin #10 and ground (brown) to pin #12. The numbers are on the wiring harness plug so you can tell which one is which.

Ok, I've checked my notes (and also worked on one of these light boards) today and from the top of the T, they are Brown, Green, Red.

And the way the pins are numbered (looking at the pins with the 'T'
standing up): the lower right side is #1 (even though there's no pin there) working up to #6 at the top. Lower left side is #7 with #12 at the top.

Hope I made that clear enough, but if there's any confusion, get back to me!

Title: Re: aww crap, help needed with tacho connec
Post by: oz_johnno on March 21, 2012, 12:39:46 AM

I finally got to putting it all back together today wirespokes and you were right, Green does go in the middle, but the red and the brown were arse about.

thanks for helping anyways, but eventually I found the correct connection here (http://bmwmotorcycletech.info/tach.htm)

close buddy, but no cigar :)

all back together and running fine now.......

OZ

Title: Re: aww crap, help needed with tacho connec
Post by: tvrla on March 21, 2012, 10:17:02 AM

Quote

...but the red and the brown were arse about.

Well, that's very interesting. Help me figure this one out, because my manual very clearly shows Brown going to terminal #12, which is the top one (closest to the top of the T).

Also, because you referenced a Snowbum page that deals mostly with converting mechanical to electronic tachs, I'm getting the idea your bike isn't an 86 or 87 model that came with the style light board you pictured. What gives?

As far as I can tell, every one of the electronic tach models with the style instrument pod you pictured have terminal #12 as the ground connection, #10 as the Signal and #8 is the hot lead to the tach.

Something smells fishy up in Denmark - to quote a famous author.  :D

So what's going on here???