I think I read somewhere long ago that the "blinker"
was created by fusing two dis-similar metal strips (conductive)
together. Because dis-similar metals heat at different
rates, the 'two-metal-strip'(di-electric) causes a 'warp',
disconnecting the contacts from......then as it cools, it re-
connects, re-starting the process. Hence, on OPEN
(broken element) bulb might(will)cause a different blinker rate.
My 98 Olds does this when the bulb comes loose from the socket
in the front bumper.
(fast blink rate)
It does this often enough that I keep wondering if I'm young enough
to walk home from the boneyard when I drop it off.(12 miles and I
used to be a Boy Scout)
But MAN does it have a large trunk!
Check your bulbs and grounds; I hope it isn't the dreaded
'bulb-out-relay'.(in your case I think it's under the ashtray)
Good luck!, Malcolm