[hortoncode3]

My speedometer crapped out, needle moves, sticks, moves, sticks, ect…odometer works perfectly. So, i replaced it with one from Hitchcocks. Plugged right into the old harness. HOWEVER, when the left indicator is on the whole speedometer blinks. Nothing on the right indicator though. And no neutral light, hi beam or amber indicator light. The ONLY thing i did on install was place an led in the speedo light socket since Hitchcocks sent it without a bulb.
Ideas? Hitchcocks think the LED light fudged up the works.
I’d fix the old one if anyone has ideas about how to do that.

[richard211]

There are differences with the wiring pins over the years, I think what's happened is the illumination bulb (when the park light is switched on) and the left indicator is swapped around. Why don't you swap the speedometer wire harness and bulbs over from the old speedometer and see if that works fine?

 Also bear in mind the LED bulbs have to have the correct polarity. If it does not work take the bulb out and rotate it by 180 degrees and reinstall it.

 The other thing you can do is verify that the wire colours match on the speedometer harness and the main wire harness it plugs into. If it does not, you could easily swap the pins / terminals over,  if you wanted to use the new harness.

[AzCal Retred]

Do you own a VOM meter? These bulbs fit into a rubber holder and slip into the speedo housing. Use the VOM to see if the circuits are functioning properly and then plug them in. If it worked before, likely it's the connections didn't all get back exactly where they started. Get the downloadable manual from Hitchcock's, it has a wiring diagram in it. Between the VOM and a wiring diagram you should be able to figure it iot.

MOST LED lamps are reverse polarity protected. If they aren't, hooking them up backwards creates a one-time flash...

[Yinzer]

I'm confounded by the black/green AND black/white wires BOTH going to the flash indicator.
How does the left blinker not back feed the right & vice versa?

(I believe the "right trafficator is mislabeled in the diagram and is the bulb below it)

[Flaekingr]

I had this exact problem a few weeks ago, it was a bit of exposed wiring causing a short circuit. Worth checking, even with new stuff

[AzCal Retred]

The indicator bulb connects to both the (+) L & R wires. Since the trafficator bulb filaments all connect to (-) ground, the bulbs of the signal side not energized provides a ground path for the indicator. Clever, eh?

I posted an elementary of this in "350 India Bullet, right indicator problem" a couple days back & discussed this very thing.

[Yinzer]

Clever, eh?

Soooo.... The bulb apparently isn't a dual filament (no separate # from the high beam/neutral warning light)
That must mean that the center electrical contact of the bulb is connected to one + conductor and the metal base of the bulb is connected to the other + conductor.
The bulb would then light & provide enough resistance to not illuminate the turn signal on the downstream side of the circuit.

I'm sensing the Prince of Darkness had a hand here. 

Also...Am I correct that a LED bulb would not function for this application on account of them having polarity?

Additional thought...This would be an easy way to "make 4-way flashers".
You just jump the bulb with a switch.

[AzCal Retred]

It's easy to overthink this. For example - When applying the Left TS switch, (+) hits the Left TS bulbs AND one side of the indicator bulb. This is a parallel circuit. The other side of the Left TS bulbs is solidly bolted to battery negative (-).

The Left TS bulbs send  the (+) to ground (-) thru their filaments, there is 12V dropped across each TS filament, max operating current, they light up.

The Indicator filament is also connected to the Right TS bulbs which are not energized(+) when the left turn is selected. The other side of the Right TS bulbs is solidly bolted to battery negative (-).

The (+) applied to the TS Indicator passes thru it, then thru the Right TS bulb filaments and then goes to ground (-); this is a series circuit. 12V drops across the combined filaments on its way back to (-) Ground.

The Indicator bulb has a high filament resistance compared to the turn signal bulbs. This results in the majority of the voltage dropping across the indicator filament. The Indicator bulb resistance also largely determines this portion of the circuit current flow. So the Right TS filaments don't have enough current to glow, but the Indicator does.

LED lamps are complicated devices. A LED has to use resistance to control current magnitude. Depending on internal construction, they can be directional or not.  A single Regular diode is used to make them directionally protected, they'll only glow if wired in properly. BUT - a "diode bridge" will allow the LED to operate "bi-directionally", the bridge automagically reroutes the applied DC (or AC) voltage to always be the proper polarity across the LED. All of this hardware can be built into an LED "lamp". SO - IF the LED bulb is a "Bi-Directional" lamp, it'll work fine in your TS Indicator.

As far as a "4-Way Flasher", jumping either the Indicator or the G/W & G/B with a small toggle switch would get you there.