Hi, I recently bought a 2001 Monte Carlo SS back in late January and so far its mainly seemed to have three problems:

1) It had a questionable PCM which we replaced (you had to add pressure to the top of the PCM metal case to make it work) but so far its worked but the car has just quit twice, and some of the guages (specifically heat and oil) do not want to work. I was wondering if there was a "engine relearn" or something similar it needs to actually be proper, I know some vehicles need to be ran 50+ miles for their O2 sensors to read correctly or their crank sensors to update, and I can't find anything if that is the same with a Monte.

2) When we first got the car there is was a kind of noise similar to a bad axle in the front, we replaced the only axle that looked even remotely bad however the noise persists and the best way I can describe it is if I turn to the right a high pitched rattle sounds similar to a piece of tin being battered to death. We've looked under the car numerous times and see nothing lose or anything that would be making a noise except maybe a single rubber bushing on the passenger side (the metal on the inside is there but no the absorbent rubber.)

3) The blinkers (by that I mean the intermittent not working and needing to press the hazard switch to make them work temporarily,) is there a real permanent fix to them or is it just something I'm going to have to live with?

 

1) Gauges actin up can be the stepper motor. I had to fix mine years ago on my Monte. The gauges are also controlled by the BCM located near the parking brake, need to remove the lower dash panel by the floor to get access to it

2) I'm thinking wheel hubs. Also check the sway bar bushings and tie rod ends. I had something similar when turning left after replacing the lower control arms, an alignment fixed it up as I was off. Though before i did the alignment from the lower control arms I also did the inner and outer tie rods since i didn't want to pay for an alignment again

3) My blinkers sometimes go faster and slower. I'm thinking BCM issues for my own problems but I'm not too worried about it yet. You might want to check grounds and for corrosion. Also check for corrosion in fuses that does happen and prevented my other vehicle from starting since it was so bad. Then a new relay worked wonders and i could start again

 

1) It's likely the gauge steppers are bad if they didn't work before the PCM was replaced but their sending units could also be bad, I"m not sure if either would send a code. Steppers going bad is a common issue, my fuel gauge goes from empty to full and back several times during a drive. I had to replace the temp sending unit years ago because the gauge never moved but the engine ran as if it were cold and not at operating temp.

2) Not sure about the noise but you say you replaced the axle but not the hub/bearing, Bad bearing would be a guess. Jack up the car and see if the wheel exhibits noticeable movement in/out when you grab at 9 and 3. You could also spin the wheel and see if you feel roughness or hear anything.

3) The hazard switch in the dash controls the turn signal blinking. Mine used to blink slow until I pushed the switch on/off. A new one solved that.

 

I have a 2002 Monte Carlo SS & am having the same issue.
My blinkers stop working completely & I need to press the hazard switch to make them work again. Sometimes repeatedly.
Usually happens after it rains, but not always.
Does yours have any water entering the car that you know of?
Where would be a good place to check for corrosion if any?