Topic: Police Bike Speedo Wiring CB750K6

[Michael86]

Hello,

I'm helping out my uncle by figuring out what's wrong with his wiring. He bought it and kept blowing fuses and melting the fuse box. Turns out that the light wiring was wired incorrectly behind the headlight so I'm in the process of cleaning all the wiring under there and then reconnecting them. I have a few K6 wiring diagrams and MOST of the wires are pretty straight forward. I have to verify the right handlebar wires but that's easy enough to do (the issue there is wire colours are not the same as the diagram. Probably because this was a police bike or the colour faded with time).

My current issue is that the Police Speedo has extra wires that are not listed the wiring diagram and I want to know where they should be hooked up (even if I don't need to hook them up).

Wires:

2x Brown/white - believe these are the standard backlight wires (just not getting any light when applying 12v...
1x Red/Black - Lights up the Right side light on the front face (Red light - assume this indicates that the RED police flasher is on?)
1x White/Black - (next to the brown / white) - When powered this lights up the other light on the front left. Whitish / Blue in colour. I assume this indicates that the BLUE police flasher is on?
1x White/Black - (bottom with some green marking on housing) - No idea...this was hooked up together with the other white/black but I assume it was incorrect and that they just happen to be the right colour?
GND SCREW - this is on the left and the nut ties into the green ground.

Really hoping to understand the purpose of each wire and where it goes or get a police wiring diagram for this bike (or a similar year / model with this speedo).

Any help is appreciated!

Thanks,
Michael

[bryanj]

Go to the UK forum and look up JamesH he recently did a police bike and may know the answers for you

[Michael86]

You're a legend! Found his rebuild post and on page 1 he has an image of it! I've registered so I can DM him and hopefully get a better - higher res of it. But absolutely amazing. I spent hours searching for wiring diagrams.

[bryanj]

The quality of his restorations is second to non, i believe he accepted a ridiculous offer for rhe Police bike and is now doing a "pair" of early 750's

[Michael86]

agreed. Amazing work.

Here is a summary of my findings:

2x Black/White (Tied together)
2x Brown/White (Tied together)
1x Black/Red
1x Ground Lug

Black/White Wires:
The Black/White wires go to the Manual speedo meter stop switch (which this bike is missing), from there it would then go (as a red wire) to one of the two red ignition wires (the one that goes to the main harness behind the light). This red wire appears to also provide power to the rear “Brief box light” which this bike also does not have installed. (These wires ARE NOT CONNECTED for now).

Note: The black/white wire that has green over the top is connected to a little solenoid inside, which when it gets a 12v signal it throws a little pawl thingy into a fine toothed gear wheel. This locks the speedo needle at the desired speed. Presumably to show to the speeding motorist that he has exceeded the legal limit. The other one is an indicator light to indicate that it is activated white or whitish blue.

Brown/White Wires:
The Brown/White wires go to the Brown/White terminal in the main harness which leads to the Keyswitch. These are the speedo running lights.

Black/Red Wire:
This wire is not the same on either the 450P or 750P (not sure the year) diagrams that I found, however, it makes sense that it is an indicator light showing that the Patrol lights are activated as in both diagrams the patrol lights are connected to Black/Red. This light is a red light when activated.

Ground Lug:
Self explanatory