'79 Turn Signal Issues

[surfbus23]

My '79 bus finally has power and so I've had the pleasure of discovering a turn signal issue. Been looking at this for a few hours and am stumped. Before getting power, I redid all the wiring using new AMP terminals and cleaned up all the contacts that could not be replaced. I've double and triple checked my wiring per the Bentley and everything seems as it should. Also, new bulbs per spec from WW everywhere.

In fact, everything is working properly except the front turn signals and here is what is happening.

I was initially unable to get the front turn signals to come on. I found some weird behavior however in that if I pulled the light switch into the on position the turn signal lights would illuminate along with the other lights. I set about checking the voltage that was being delivered and got a solid signal all the way into the housing (which makes sense given the rear signals are working perfectly).

Next step, is I pulled the bulbs and sprayed some deoxit into the housing. Now if I fiddle with the bulbs I am able to get one of two results. If I'm very delicate I can get the turn signal to work correctly on both the front and the rear, but it will blink quickly. If I'm a little less careful and just put the bulb in I can the front and rear to blink at a normal speed, but it seems to be crossing over and also causing the side markers and the license plate light to blink. Worth noting that the license plate light will blink like this on both the left and the right blinker.

As I said I've triple and more checked the wiring compared to the Bentley. From everything I can see I've got it all wired up right. My best guess right now is that my signal housings are shot. The reflectors have mostly turned the blue color that I believe is a sign of corrosion.

Is there anywhere else I could have messed up the wiring to create this crossover between the turn signal and the marker/parking/license plate lights or do I just have junked housings?

Thanks for the ideas!

[Tcash]

make sure the bulbs are in the sockets correctly.
Note the two contacts on the builb need to line up with the two contacts in the tail light housing.

[telford dorr]

Connect a test light from each turn signal wire (at the lamp holder) to ground and see if it flashes (normal or fast). If it does, and the bulb in the lamp holder doesn't, then the lamp holder, bulb, or ground wire is suspect. If the test light doesn't light at all, then the problem is upstream, most likely in the dash area. If the test light lights but doesn't flash, check the flasher relay.
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[Tcash]

If I'm a little less careful and just put the bulb in I can the front and rear to blink at a normal speed, but it seems to be crossing over and also causing the side markers and the license plate light to blink. Worth noting that the license plate light will blink like this on both the left and the right blinker.

The side marker and lic light flashing, if not due to the bulbs being in wrong, could be the turn signals looking for a ground.
Tcash

[ToolBox]

Grounds are my first thoughts. Get some clip leads and hook to a known good ground and the bulb holder and see what happens. Clean the bulb holders and the bulbs. Make sure the right bulbs are installed. While you are in there make sure the park light bulbs are good too.

[Tcash]

Light Bulb Chart T2

[SGKent]

almost all late bays lose the top of the hazard switch. It is always hot so be aware. That was the source of my hazard issues when nothing else was left. The fix is fold the tabs back over the top to hold it on and wire tie it. Considering that they all do it sooner or later, even a NOS one (if one could be located) would not solve the problem.
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[surfbus23]

Thanks for the replies everyone. I spent some more time and realized that this is definitely a ground issue. Also realized the stupid things. I didn't have a dual filament bulb. Going to pick some up and hope the answer was just me being a total novice.

[surfbus23]

Well... that was silly. Nothing like spending hours on something only to find out you were using the wrong lightbulb. Ground issue caused by using a single filament bulb.

[SGKent]

[surfbus23]

Almost have everything working as it should. Just this one last strange thing with the emergency flashers. With the flashers on and the key out of the ignition I'm getting power on the highlighted circuit below.

This is causing the fuel gauge to bounce up and down with the pulsing electrical current and the alternator charge light and the oil pressure light to blink along with the turn signals indicators.

The black wire is supposed to be switched power only correct? Any ideas why I'm getting power on this line with the key out of ignition. This does not happen with the ignition switched to on. Does happen with no key in ignition and with just the key in but not turned to on.

EDIT: I should note that I'm using a fuel gauge from the earlier bays, so I don't have a voltage stabilizer to go bad. But I'm pretty sure regardless of the voltage stabilizer this wire should not be getting any power.

[busdaddy]

One (or both) of your idiot light signal arrow bulbs is too high a wattage and current is backfeeding through the filaments, the arrows use the ignition circuit as the ground when the key is off.

Edit, do you have a coil and carb choke heater(s) installed and hooked up?, if the engine is out there's not much load on that circuit.
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[surfbus23]

[busdaddy]

The gauge doesn't bounce on an early bus when the hazards are on, but most have a choke heater involved in the ignition circuit as well, that's a fairly large load. You may just have to live with it and hope you don't have to use the hazards often if the bulbs turn out to be the correct wattage already.
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Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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[Tcash]

Make sure the wires on terminals 15-30 on the hazard switch are the right wires.

[surfbus23]

Wired up correctly. I've also tested the wires at they operate as they should. BD seems correct in that it is sending some power through that wire and probably needs more load on it that isn't being provided by my non-stock carb setup.