I have a strange electrical problem which involves my signal flasher on my 99 Blazer.
When my ignition switch is on, my signal flasher is continually flashing (bink-bonk-bink-bonk). This is not to say that either the turn signals or the signal indicators are on, they are NOT.

When I press the brake pedal, the flasher stops, but resumes as soon as I release the pedal.

I bought a new flasher and installed it, but the new one buzzes instead of flashing.

Both the existing and the new flashers work normally when the signal switch is on, either direction and in either lane-change mode, the Emergency 4-Ways work noprmally, too.

Note that last winter, the right lane-change mode ceased to work properly, The front outside signal worked, but not the back, the indicator acted as if I had a burned out bulb (beating double-time), now it is working fine.

I checked voltage at each of the 4 leads to the flasher and am confused by what I get (.07 volts at one and nominal 12 at another).

Can anyone tell me what voltage or resistance to expect at each of the terminals and in both ignition on and ignition off. Also, I do not have an electrical schematic, is there on available online anywhere.

Has anyone else encountered a problem like this?

 

This indicates that there is a problem within the multifunction switch. A search for "clicking+behind+dash" should turn up some relevant threads. The first approach I would take is to replace the hazard switch itself as this is the cheapest route.

Here are a few tech articles that will prove helpful:
Broken Hazard Switch Repair
98+ Hazard Switch Replacement
98+ Multifunction Switch Replacement