Knocking sound from the rear

[Chevrolado]

So, I'm not sure if its valid, but I'm sort of thinking that it is definitely air related to the temperature (as you have found here).
The airbags might be set not to fill completely when cold like this because as it warms up, air expands. When its cold, air contracts.
So they probably have it built in so it doesn't go and overfill the bags. If it DID then when the air warms up, the bags could expand to a point of blow-out.

I would call the company back again and ask them about temperature vs the how the system works. Tell them that apparently when its cold and the air is all contracted, you are experiencing some metal on metal contact somewhere and you are concerned. I'm sure they have dealt with something like this before..

 

[Yukongk]

Sorry guys, I found the problem. I ended up creating a new thread bc I needed quick advice before having to drop her at the mechanic. It is definitely related to the air shocks. The compressor won't turn on at all now and it is cold again where I am. Not sure if the new Arnott compressor is defective or if it is the SCM. I am waiting for the mechanic to call me with bad news to ruin my day
Arnott said that if the shocks aren't filling with air, this would absolutely cause the noises I am describing.

I just hope I get it fixed so I can enjoy my truck and hope the shocks aren't damaged now bc of this.

 

[Chevrolado]

Oh okay.. Good luck. Hopefully it works out.

 

[zieglerj-pdm-specialist]

Sorry guys, I found the problem. I ended up creating a new thread bc I needed quick advice before having to drop her at the mechanic. It is definitely related to the air shocks. The compressor won't turn on at all now and it is cold again where I am. Not sure if the new Arnott compressor is defective or if it is the SCM. I am waiting for the mechanic to call me with bad news to ruin my day
Arnott said that if the shocks aren't filling with air, this would absolutely cause the noises I am describing.

I just hope I get it fixed so I can enjoy my truck and hope the shocks aren't damaged now bc of this.

If you have them change it out if it is bad it will run you $900 and if you change it on your own it will only cost you an hour of your time and $120. I dd it and it was well worth it. I changed it with an Arnnot compressor.

 

[Yukongk]

If you have them change it out if it is bad it will run you $900 and if you change it on your own it will only cost you an hour of your time and $120. I dd it and it was well worth it. I changed it with an Arnnot compressor.

Where can I get an SCM for $120? Thanks

 

[zieglerj-pdm-specialist]

I got my Arnott Compressor on Ebay for 120 Brand new. All you have to do is Unbolt a couple 14mm bolts behind the back driver side rear tire and unhook a couple hoses and a wiring harness it will drop out then with the Arnnot is you need to unscrew the top of the compressor and change out the water filtration beads that are included and screw the top back up bolt it in just like you unbolted it. Hook the hoses back up after its bolted in. To get the error on the screw you just need to unbolt the negative terminal on the battery for 10 minutes and the error should be gone and you should hear the compressor turn on for 10 seconds then quit. If it runs all the time you have a air shock problem and that would require a professional to do those. I got lucky and it was only the compressor. Ok I forgot to check the hoses so they are in good condition so there are no tears or leak in the hoses on the compressor and if there is you just need to replace the hoses on the compressor..

 

[teginder81]

This noise comes from the rear air conditioner system. It's a small actuator that opens a damper or vent. Whe it goes bad it skips gear and that is were the knocking comes from. I replaced mine for about $40 and less than half hour of labor. The computer for the hvac is calibrated automatically when the ignition is turned on and left alone for a little over a minute. Aftr wards the system could be used normally and it should work if there is an issue with the settingns not corresponding to the settings in the control units. Disconnect the plugs from the rear of the control unit in the front and the one in the rear with the key out of the ignition. After plugging them back, start the car and let it run for a little over a minute. The system will calibrate itself and reprogram all controls. Hope this helps!!!