Working on a 2005 Chevy Malubu and the left front turn signal comes on but does not blink while the left rear turn signal blinks at an extremely quick rate compared to the right side. Tried changing the front turn signal bulb and did no good. Could it be the rear bulb is messed up?

You have a body control module problem, more then likely . The BCM turns the turn signal on an off. Have a scan tool hooked up (a profesional grade scan tool ) One that can read codes in the BCM.

Turn Signal Lamps
The STOP/TURN/HAZARD fuse in the instrument panel (I/P) fuse block supplies battery positive voltage to the body control module (BCM) for the turn signal lamps. When the turn switch is placed in the LEFT TURN or RIGHT TURN position, ground is applied from G202 through the turn switch, to the turn signal switch signal circuit and to the BCM. The BCM then applies battery positive voltage to front and rear turn signal lamps supply voltage circuits. The left front turn signal lamp is grounded at G100, right front at G101, left rear at G301 and the right rear is at G302.


DTC B3948 Left Front Turn Signal Circuit

The turn signals are controlled by the BCM
Turn Signal Lamps
The body control module (BCM) is responsible for controlling the turn signals and hazard lamps. When the turn signal switch is placed in either the left turn or right turn position, the BCM receives a signal from the turn signal switch. The BCM then sends an on-off voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator. When the hazard switch is pressed, the BCM receives a signal from the hazard switch. The BCM then will send an on-off voltage signal to all the turn signal lamps. All the turn signal lamps will flash including both IPC turn signal indicators.

I would suspect a problem with the BCM or maybe corrosion in the under hood fuse box . Wires from the BCM to the front turn signals go through the underhood fuse box.
Your best bet ,take it to a qualified repair shop that has a diagnostic scan tool that can read BCM DTC'S - diagnostic trouble codes
DTC B3948 Left Front Turn Signal Circuit
The body control module (BCM) controls the left front turn signal, hazard lamp, and daytime running lamp (DRL). The BCM supplies voltage to control the lighting functions. The BCM monitors the left turn signal lamp supply voltage circuit for proper operation.
DTC B3949 Right Front Turn Signal Circuit

Get the left signal to flash fast then walk around the car to see which light isn't flashing then change the bulb or socket if they all appear to be flashing (front and rear) turn on the right turn signal then look into the front and rear lens and count the number of bulbs flashing, now do the same thing on the left. Many times there's more than 1 bulb in each lamp. I hope this helps. Take care.

Buy a two pack of turn signal bulbs. Change the front and rear left bulbs and try it out. If you're lucky, you're done and got away cheap. If not, start chasing electrons. Not an overly complicated circuit, the signal is quick flashing because you have an inoperative lamp.

Could be a faulty socket too. The flasher "blinks" slow when all lights are functioning. A short to ground, to another circuit, or an open circuit can make the flasher blink fast.

Replace the turn signal switch. All of these lights run threw it.

The inside light is blinking quickly because the front blinker light is out. I'm afraid that without more info I can't tell you why the lights are out.

check your bulbs.A burnt bulb or a poor connection at the bulb is the usual cause.

any increase in bink speed is direcly related to a bulb being burt out.

sounds like the bulb you have is the wrong resistance the new noen bulbs will do this