Hazard Flasher Staying On?

Here's a weird issue: Sometimes when I go to turn on my flashers, the lights come on but never turn off. After turning or shifting gears it will sometimes start working again. Other times, turning/shifting makes them stick on. Killing the hazards shuts the lights off every time (only happens when hazard is on).

I've replaced the hazard flasher (was the factory thermal flasher, right now I have Peterson 554 Eletronic Flashers installed for hazards and turn signals) which didn't change the situation. FWIW the turn signals work great (the Peterson ones are well made, much better than the crappy Innova 554 I was running before)... so unless both the old flasher and the new one I installed both have the exact same issue, I doubt that's it.

Knowing how two prong flashers work, I'm scratching my head as to what's going on... something shorted out in the turn signal/hazard switch?

That is a strange one.  But you actually use your flashers?  The flashers not just the turn signals?  

It should mechanical given that shifting gears can change it.  And since you have an AOD, I assume you mean moving the shift lever rather than the tranny shifting gears on its own.

That suggests that the turn signal switch may be the culprit, and the fact that turning changes things seems to support that theory.

The turn signal switches are quite complex and can do a myriad of things.  But aren't cheap.  It would be good if you had a spare to switch out.

the turn signal switch is a combination assembly that holds the turn signals, hazard switch and the horn contacts. if any one of these gets worn down then a new assembly is the proper fix. normally considered during a steering column rebuild. if you have the aod then you probably have the tilt wheel also and that does make it a 3 1/2 hand job sometimes. I don't recall or maybe you did not say, did you install led bulbs? if so, they require a certain flasher which is self-timing due to the absence of resistive load to heat the thermal flashers. Just being an electronic one may or may not be enough. if you did install led bulbs then just swap one back to test  

No on the tilt wheel. First vehicle I've owned without it.

Yes when I mean shifting gears with the lever.

No on LED bulbs. Both flasher units (hazard and turn signal) are electronic Peterson 554's. Turn signals have never had an issue... all the issues have been with the hazards, both with the original thermal unit and the new electronic unit.

Yes on the hazards... not just the turn signal. I do use them if I'm stopped in a "no-stopping" place. But I originally noticed it when in a funeral procession.

Horn/Cruise contacts are suspect on mine... it's had some weird cruise button related issues (cruise stops responding to button inputs once warm, starts working again when stopped and cooled off). I didn't know that the slip rings were part of the turn signal/hazard switch. Maybe I need to pull my wheel and disassemble/clean the contacts (same thing I had to do to my Ranger a month ago). Perhaps I'm having leakage current in there (something is bypassing the flasher, or else it'd switch with the lighting load).

 I just recently rebuilt a column for my truck. the horn contacts were worn down horribly and the entire area was full of copper "dust". that could be an occasional short I imagine.
I don't recall but I may go back and review. did you replace the hazard flasher or the turn signal flasher?

thinking a little more on this It's possible you have a ground going bad. humidity, moisture, vibrations etc making it unreliable

Pulled the wheel last night... some dirt and debris in there but nothing terrible. Washed it out with contact cleaner and applied some silicone paste. After a test drive it messed up again. Couldn't make the hazard flasher flash until I turned off the ignition and then cycled the hazard switch.

I replaced both flashers... as I never cared for the Innova flasher I was using for the turn signals and decided to replace both at once.

I'm doubting a ground issue as AFAIK the hazard flasher is on the supply side (will check the schematics). When the lights don't flash (solid when hazard is on), they're at full brightness (dash lights and the front lights at least)... usually bad grounds show up as things losing power when other loads on said ground are high. And since these are two-prong flashers without external ground leads (not the kind one uses when retrofitting LEDs), unless I'm overlooking something, a bad ground doesn't match the symptoms.

For giggles I would check all the bulb sockets.

Sounds like the turn signal switch to me.

There's definitely interplay between them.
I've run into the situation where my turn signals won't work and inevitably find that my 4-way flasher knob isn't fully seated.

Perhaps the opposite can be true?

The cruise issue isn't fixed either... but I also rediscovered that it's not an electrical problem. There's an issue with the brake pedal vacuum valve sometimes not keeping it's seal when the pedal is pressed/released while cruise is active. Tapping the brake and re-resuming usually fixes it. Like a seating issue with the seal?

I'll need to pull that valve and see if it's serviceable (as I doubt it's an economically obtainable part?)

I think I figured something out... finally was able to reproduce the symptoms consistently: The actual issue is that I'm only losing hazards when the brake light switch is on... which (edit) upon further review is perfectly normal, especially since I don't have a center brake light.

I feel like a moron.

That's what I get for not remembering my parent's former vehicles (1987 C10, 1988 and 1993 GMC Safari's) without center brake lights... by the time the last one was gone, I wasn't of driving age yet. Doh!

Here's the diagram



I can definitely see where a brake light connection to power would override the hazard switch's connection that cycles only when it heats up. (Because it can't heat up if the voltage is the same on both sides of the contacts)

Don't beat yourself up for not understanding the circuit if you hadn't looked at it yet.
Every day is a good opportunity to learn

How would a center brake light change things?

ArdWrknTrk wrote

How would a center brake light change things?

Yes, that's my question as well.

With a center brake light, one can flash rear hazards and and still have a brake light working. It was a generalization based off how most US vehicles changed when center brake lights were added to the design. In fact, legally, the only thing allowed to turn on the center brake light *is* the brake, so such isolation is at least partially mandatory.

To my knowledge no Bullnoses ever had center brake lights (I don't think it was required for vans/trucks until 1994 or so?) so it's a moot point.

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Based on the EVTM screenshot posted such behavior is normal... and I'm just dumb.

Not just a matter of not heating up (or charging up, in my case)... the flasher's bypassed by the brake switch, and due to the way the switch is configured, that bypass is for all hazard lights. Or put another way: The brake switch ties all rear turn/stop filaments to +12V and the hazard switch ties all turn lights (to include the rear turn/stop filaments) to the hazard flasher (a common point). Since there are no diodes in play, when both are on, all are tied to +12V.