My drivers side blinker works erratically,both bulbs are new sometimes neither side works i'm thinking flasher module?

Hey Derrick,
I do not think the blinkers have a "right" and "left" fuse...Its usually a flasher/blinker relay.
Try replacing the bulbs.. make sure their sockets are clean and able to hold the bulbs tight. If you are not getting both right side blinkers to work and you know both bulbs are good, the switch in the column may be the culprit.

2003 GMC ENVOY 4 2L L6 Turn Signal Switch RockAuto

Turn signal/Flasher
2003 GMC ENVOY 4 2L L6 Flasher RockAuto

Bulbs/Sockets
http://www.rockauto.com/en/catalog/gmc,2003,envoy,4.2l+l6,1415269,electrical-bulb+&+socket,turn+signal+lamp+bulb,13675

The bulbs all have to be good for the flasher to work. The flasher is under the dash, driver side. When you turn on a blinker, do you hear it clicking under the dash. If the turn light is on , on the dash , but not flashing, then a bulb is probably bad on that side. Leave the blinker on and walk around the vehicle to check the lights. Flip the blinker to the other side and walk around the vehicle again checking lights. If all the lights are lit, but not blinking, then the flasher is most likely bad.

Have you check the fuse and or flasher? The owners manual will tell you where the fuse and flashers located

Double check your bulbs on the bad side. Your condition (fast blinker flasher, or relay,) is just what happens with a burnt bulb, or a bulb socket not getting power. Are both fron and rear inoperative on bad side? I would think that one would be blinking at a fast rate. If it's not your bulb or a bad (corroded) socket, then you have a wiring problem from the flasher to the bad side. But, first double check your bulbs.

you will need to inspect all of the left side blinker bulbs one of the bulbs that is supposed to blink is bad my buddy has a caviler that had the same problem one of the bulbs ended up being bad it was the rear drivers side bulb. there is also a flasher relay locater under the dash that tends to go bad just listen for the ticking and replace the flasher the flasher costs about 8 bucks at you autopart store ask for a flasher relay. i hope this helps.

If you mean the left turn signal indicator on the dashboard won't blink...sometimes means the actual bulb for your left blinker is out. If you mean the actual exterior blinker bulbs don't blink...may be the flasher.

may be a bad electronic flasher unit if you lost both. if the blinkers flash very fast, that is a bulb out warning, but sometimes the flasher controls both circuits, and it is a relay.

it is in the flasher switch for hazards

There are separate fuses for the turn signals and blinkers, but you should check both of them just to see if they're good.

You may have a burnt out turn signal bulb as well. I know that this sounds like an obvious answer, but a single bulb can sometimes disable the entire system because of the way that some flashers operate.

You could also have a defective turn signal/hazard light flasher. This is located under the dash board on the driver's side between the steering column and the door. You have to remove the sound insulation/kick panel (the cover on the bottom of the dash board) to reach the flasher (it is easy to remove - I don't think you even need tools).

it sounds like you need to replace the flasher unit under the drivers side dash