Thought was ground, but now thinking short. Could it be turn signal switch? When I signal right, all flashers and turn lites flash at regular speed. Left. Run signals operate fine. When vehicle is off and I press brake pedal, parking lights turn on. Also with right turn signal engaged, all instrument lights flash in time to flasher arrow in IP.
I have had the steering wheel off a year ago to replace ignition key/tumbler.
1992 vin W 4.3 4x4 blazer Tahoe.

 

Sure sounds like a ground issue to me, i cant tell you where to look but what happens with a bad ground is when you turn the right signal on the power goes through the positive to the ground connection which is usually a ring terminal with 2 or 3 wires on it bolted to the frame or body, corrosion wrecks the connection to real ground so the power runs back up the other grounds to find a path through other bulbs elements to a different ground which in turn lights them all up. One common bad ground on those is located on the drivers side frame rail near the rear bumper but im sure theres more, havent messed with one for years, maybe theres one on the passeneger side too?

 

I had a problem like this on my 94, did you recently change any bulbs on the exterior front or rear on the problem side?
When I had this happen I had just changed the bulb on the drivers side (which was the problem side) all exterior lights would flash, even the license plate bulbs, and the dash would go crazy as well. Took the bulb out, cleaned in the socket, put some new grease, put the bulb back in and all was well.

 

check also all twin filliment bulbs iv'e had a filliment break and ark to the other one in the bulb back feeding power through the system - does a lot of funky things when that happens

 

The first thing I did was replace the right front exterior turn signal bulb. I noticed the existing bulb was barely flashing, very dimly, but flashing. The replacement bulb did the same.

 

Take the front and rear bulbs out on that side, clean the inside of the socket and re install the bulbs

also, if you are unaware, there is a ground for the front blinkers located on the firewall near the headlight, you have to remove the horn on the firewall to get to it. I would take that off and clean it really well.