Autoride leveling help

[Yukongk]

Need some help in diagnosing why my brand new compressor from Arnott will not turn on. Arnott told me to check a fuse and a relay first, I believe the fuse is under the hood? Anyone know where the relay is (if there is a relay)?

Some background: Comprossor was initially working but I started getting a knocking noise in the rear during cold weather. After pulling my hair out trying to figure out where the noise was coming from, I found out that the air bags weren't filling up in the shocks and this was causing the noise. My compressor hasn't turned on all day.
Thanks

 

[OHSIXX]

http://www.tahoeyukonforum.com/forum/showthread.php?t=53764

 

[Yukongk]

http://www.tahoeyukonforum.com/forum/showthread.php?t=53764

Appreciate it. I'm going to start pulling fuses in the morning. Funny thing is that I haven't thrown any codes. I suspect this Arnott compressor is a POS.

 

[z0lt3c]

You need to check three fuses. Two of them are in the main fuse box, under hood, these are STUD1 and RTD. The third fuse is located in the panel on the driver side of the dash, and it's IGN3 (this is the most common one to go). The relay is located in a socket, protected by a small enclosure next to the main fuse box. The relay rarely fails, but the socket offers a good place to jump power to the compressor and see if it fires. If you get the compressor to run at the relay, and you don't have any codes, it's mostly likely NOT the compressor. If you cannot get the compressor to run at the relay then something is wrong in the compressor housing (most of the time).

I had a situation with my Escalade where the SCM harness actually failed, this resulting in the compressor running when jumped a the relay and no error code. In my case, the SCM was not communicating properly with the rest of the vehicle but was communicating enough to keep the error code from going on. After repairing the harness everything worked.

 

[Yukongk]

You need to check three fuses. Two of them are in the main fuse box, under hood, these are STUD1 and RTD. The third fuse is located in the panel on the driver side of the dash, and it's IGN3 (this is the most common one to go). The relay is located in a socket, protected by a small enclosure next to the main fuse box. The relay rarely fails, but the socket offers a good place to jump power to the compressor and see if it fires. If you get the compressor to run at the relay, and you don't have any codes, it's mostly likely NOT the compressor. If you cannot get the compressor to run at the relay then something is wrong in the compressor housing (most of the time).

I had a situation with my Escalade where the SCM harness actually failed, this resulting in the compressor running when jumped a the relay and no error code. In my case, the SCM was not communicating properly with the rest of the vehicle but was communicating enough to keep the error code from going on. After repairing the harness everything worked.

All 3 fuses checked out. Next is to test the relay but as luck would have it, it started snowing/raining.....to be continued. Thanks for the help guys.

 

[Yukongk]

I jumped the relay and the compressor kicked on. Guys, please help me. I have an appointment in the morning w the mechanic but rather fix it myself.

Thanks

 

[Rivieraracing]

Then it sounds like you need a new relay if that made the compressor work! Try plugging it back in and with the truck on, tap the top of the relay with a handle of a screw driver a few times and see if it gets it unstuck.

---------- Post added at 04:51 PM ---------- Previous post was at 04:47 PM ----------

Actually, still may be the sensors that aren't sending the signal to turn the compressor on. If you can find another relay to try that's identical I'd give it a try and see if it makes it work or just pony up the money for a new relay to give that a try. Def try tapping on the relay and see if that works first!

 

[z0lt3c]

Typically it's not the relay. With no codes, it could be the ride height sensors, a faulty SCM or a harness problem connecting the SCM. I would physically inspect the rear heigh sensors, they are attached between the frame and trailing arm. If you disconnect the height rod from one side you should be able to smoothly operate the sensor. Maybe the sensor rods are disconnected or jammed... You can also visually inspect the SCM and the harness by removing the cargo passenger side rear molding. Disconnect all three leads from the SCM and clean them up w/ electrical solvent.

If none of that helps, at this point you need a GM dealer w/ a Tech II tool. They will be able to query the SCM module, see if it's replying, and if it is, run all sensors through the proper diagnostic tests (as described in the FSM). Don't bother taking it somewhere if they don't have a Tech II.

 

[Yukongk]

Typically it's not the relay. With no codes, it could be the ride height sensors, a faulty SCM or a harness problem connecting the SCM. I would physically inspect the rear heigh sensors, they are attached between the frame and trailing arm. If you disconnect the height rod from one side you should be able to smoothly operate the sensor. Maybe the sensor rods are disconnected or jammed... You can also visually inspect the SCM and the harness by removing the cargo passenger side rear molding. Disconnect all three leads from the SCM and clean them up w/ electrical solvent.

If none of that helps, at this point you need a GM dealer w/ a Tech II tool. They will be able to query the SCM module, see if it's replying, and if it is, run all sensors through the proper diagnostic tests (as described in the FSM). Don't bother taking it somewhere if they don't have a Tech II.

I want to inspect the SCM. Any pics of the exact location? Right now I am picturing the area where there is a rubber plug and a bunch of wires coming into the vehicle. If this was the drivers side, it'd be exactly where the factor sub is.

 

[z0lt3c]

On the inside of the vehicle, in the rear cargo area, directly across from the sub and/or jack location. Here is what it looks like with the molding removed... You shouldnt have to pull the molding all the way off, just enough to get to the SCM (silver box)





BTW- I have an extra SCM module for sale since my problem turned out to be the harness.