New speedo installed, but turn signals don't work

[VegasMichael]

Hello all! First of all, I know absolutely nothing about wiring or electronics.

Here's what happened: I replaced the '79 Special's speedo with one from a '79 650. Everything went pretty smoothly and the new speedo works fine. Unfortunately, the turn signals no longer work at all (nothing happens when I hit the turn switch). All other lights are working fine.

Both speedos had the same color wires (blue, white with green stripe, and 2 black), but the new one had no 4-pin connector with it, so I just connected the like-colored wires directly. It's possible that I mixed up the blacks, though. Would this make a difference? Which color wires are for the turn signals (or all they ALL needed for the turn signals)?

I've checked the Clymer manual and the colored wiring diagram, but can't make any sense of either. (The color diagram appears to show a brown wire for the turn signals, but none of my wires are brown.)

Thank you!

[kboehringer]

Check the grounds

Mike,

You should have a GREEN for Right and a BROWN for left. I'm not the level of expert you will find around here but I'm not sure why your signals would not work after changing a speedo. I'm not sure I understand this change of wires to accommodate the speedo?

I know I've had several problems with my signals and they were always resolved by fixing a bad ground. You may have knocked the grounds loose when working in the headlamp? To the best of my knowledge all the blacks in the head lamp are grounds.

You could try (just for testing) connecting/holding a wire to the nut that holds the signals to the lamp bucket and the other end to a GOOD ground like the main frame, horn mount, or other. A pair of alligator clips makes this kind of testing pretty easy. If they work with your test ground you need to double check all the ground wires.

I was messing around with my signals last night, had a similar problem, and it turned out the ground wire was not making good contact with the signal mounting stud.

Hope that helps.

KURT

[VegasMichael]

Thanks! I guess the BIG assumption I was making is that the speedo wiring has something to do with the turn signals, but it sounds like it doesn't. I assumed that this was what I'd screwed up.

I guess it's time to locate the actual turn signal wires and see what I can find. The area behind the headlight is a rat's nest of wires, so it's fairly likely that I knocked something loose while working back there.

[3Phase]

Michael,

The wires for the Speedometer should be:
Blue = Instrument lighting 12 Volts
Black = Instrument lighting ground
Green/White = reed switch voltage in
Black/White = reed switch voltage return

Does one of the two Black wires have a White stripe?

If both wires are Black with no White stripe, just jack up the front wheel and spin it. Put an Ohm/Continuity meter probe on the Green/White wire and each of the Black wires to figure out which wire is for the reed switch and which one is the instrument lighting ground.

The reed switch in the speedometer creates timing pulses the self-cancel unit uses to calculate the distance traveled since the Signal was activated. The Signals will work just fine without the reed switch -- and the self-cancel unit -- but the self-cancel distance calculator won't.

For reference, the Signal wires don't run through the Speedometer:
Dark Green wire = Right Turn Signals
Chocolate wire = Left Turn Signals.

If you're like me you'll remember this until SQUIRREL!


.

[VegasMichael]

Thanks, 3Phase - that was useful in testing.

Update: After much time yesterday spent checking all the grounding in the signal wires and getting nowhere, today I started up the bike and the turn signals worked perfectly. Bizarre. So I learned a lot about testing the electrical, but at the same time learning nothing about fixing stuff besides "If you just let it sit overnight, it fixes itself."

Also, a big win: The speedo lights actually work. I fully expected this to take more experimentation, given that (upon further inspection) the old speedo had a black wire with a white stripe and the new one just has 2 black wires. I'm not concerned about the self-canceling feature -- I've never had a bike that did this well, so I always cancel them myself anyway.

Thanks all!