99 Tahoe. Left side signals flash. Right side does not but both front and rear bulbs are on.

computer glitch do not know if you got last answer so here we go again

You have a right front or rear turn signal/parking light bulb blown.

turn on flashers it might help locate which one .
Remove the lens cover push and twist to remove blown bulb
replace with 1157 2 element bulb
install reverse order
Hope this helps Mike

Check for a bad ground as all you have stated could be the result of a ground wire with a bad connection get back to me if you need more help Thanks Ray

Gday mate, we had a problem with another late model vehicle similar to that, the bulb that was put into the reverse light was not exact brand product ( ohmage was slightly wrong ) and fowled up computer, correct bulb in place and disconnect battery to reset K A M ( keep alive memory) problem solved, BEWARE, some vehicles cannot have KAM reset except for dealer computer tethered reboot , just try putting the factory correct bulb(s) in and see how it goes, geoff. hope this helped.

Its a bad bulb. They might look ok but sometimes they are devils. Change the bulbs regardless. If you change the right side and problem still exists change the left side as well and this should fix your problem. Please rate if this is helpful

Replace the burned out bulb. It is flashing fast to alert you that bulb is burnt out. Turn on the side that works properly & note all bulbs flashing in front, rear & side. Most likely there is at least 1 burnt out on the other side.

Howdy,
First look for a burned out bulb on the side that flashes faster. Look carefully. Go to the right side that flashes normal and see how many bulbs flash front side and rear. then turn to left side and look, you may find one bulb burned out.
Good Luck !!!!!!!!!!

I have exactly the same problem on the same molel car 2001 Accura 3.2CL , could this be a relay problem? The problem is, let me repeat, "Left turn signal flashes way too fast. front and rear, bulbs are are good and lighting so it is not a bulb. the right side is fine and the same bulbs are lighting on that side .....". (This is my question rather than an answer, I hope this will help to find a solution)

I had this problem, and to be honest, it happened to the left side about a week later...it's the board that the bulbs plug into...it's a very common problem with this model. So popular that you can normally get the socket board off the shelf at a parts store! it's extremely simple to replace, and I replaced all the bulbs at the same time!

Check the front lights. Usually if i flashes fast it indicate a bulb is out on that side.