2001 Suburban auto ride compressor deep dive troubleshooting

[nvetro]

I have a 2001 Suburban 1500 LT with the auto ride rear air suspension. On my last trip towing my 22' Hallmark inclosed trailer I noticed the compressor did not kick on when tongue weight was adding which of course caused the rear to sag.

Thinking it had to be the compressor since searching the web focused on the compressor (namely the exhaust solenoid) going bad. I went to CarQuest and picked up a new compressor and installed it and the compressor STILL did not kick on even with tongue weight. I do not have a service ride suspension indicator on my dash (this is likely because I am having a Suburban 2500 dash because I wanted a trans temp gauge and maybe this alert is disabled). I also do not have any codes stored when I used my scan tool.

I applied power and ground to the compressor connector and it ran and applying power to the exhaust solenoid leads on the compressor made it click, thinking MAYBE I got a bad compressor I returned it and got a new one, of course this did not fix my problem. I went a step further and applied power to Pin 30 and Pin 87 of the ALC relay under the hood which should trigger the compressor to go on, this did NOT work and I tested pin 30 was showing 12V just fine and the jump to 87 was working.

Other things I've checked are the IGN3 fuse (inside), Stud #1, and the RDC fuse under the hood, all came up fine. I also tested that there is 12V power at the connector which connects to the compressor (both the 12V main lead and the power lead that goes to the exhaust solenoid. When I stand on my hitch I hear a click coming from the compressor area, which I bet is the exhaust solenoid perhaps.

Anyway, I've checked everything I know and from searching forums. The harness looks in good shape as do the ride height sensors, could I be looking at a bad SCM (Suspension Control Module)? Thats the unit behind the right rear plastic in the trunk. The WEIRD part is when I jump pin 30 and 87 on the ALC relay the compressor doesn't come on, would a bad SCM cause this since I assume power runs through that unit?

Please help

 

[nvetro]

anyone?

 

[nvetro]

Ttt

 

[OHSIXX]

I have a 2001 Suburban 1500 LT with the auto ride rear air suspension. On my last trip towing my 22' Hallmark inclosed trailer I noticed the compressor did not kick on when tongue weight was adding which of course caused the rear to sag.

Thinking it had to be the compressor since searching the web focused on the compressor (namely the exhaust solenoid) going bad. I went to CarQuest and picked up a new compressor and installed it and the compressor STILL did not kick on even with tongue weight. I do not have a service ride suspension indicator on my dash (this is likely because I am having a Suburban 2500 dash because I wanted a trans temp gauge and maybe this alert is disabled). I also do not have any codes stored when I used my scan tool.

I applied power and ground to the compressor connector and it ran and applying power to the exhaust solenoid leads on the compressor made it click, thinking MAYBE I got a bad compressor I returned it and got a new one, of course this did not fix my problem. I went a step further and applied power to Pin 30 and Pin 87 of the ALC relay under the hood which should trigger the compressor to go on, this did NOT work and I tested pin 30 was showing 12V just fine and the jump to 87 was working.

Other things I've checked are the IGN3 fuse (inside), Stud #1, and the RDC fuse under the hood, all came up fine. I also tested that there is 12V power at the connector which connects to the compressor (both the 12V main lead and the power lead that goes to the exhaust solenoid. When I stand on my hitch I hear a click coming from the compressor area, which I bet is the exhaust solenoid perhaps.

Anyway, I've checked everything I know and from searching forums. The harness looks in good shape as do the ride height sensors, could I be looking at a bad SCM (Suspension Control Module)? Thats the unit behind the right rear plastic in the trunk. The WEIRD part is when I jump pin 30 and 87 on the ALC relay the compressor doesn't come on, would a bad SCM cause this since I assume power runs through that unit?

Please help

So far you have done the same if not more trouble-shooting about this issue than when I looked into mine: http://www.tahoeyukonforum.com/forum/showthread.php?t=53764

The autoride is a great feature but a PITA if it fails..... I'd think the SCM would be a good place to start at this point. Maybe try to find one at a local salvage yard. I know mine had alot of dirt and crud all in that area-great place to mount it GM.... Did you try just pulling apart the connections at the SCM to see if something got lose? Maybe spray some contact cleaner on the connections too....

You are at the point of my technical knowledge on this subject but just thought I'd chime in. GL and keep us posted with your fix.

 

[OHSIXX]

http://www.tahoeyukonforum.com/forum/showthread.php?t=73801

 

[Rocket Man]

After replacing my compressor it wouldn't run either and the mechanic at a different shop found a wire at the compressor harness that had corroded and wasn't conducting. He said it was a ground wire. People always forget grounds are as important as power wires and don't check them. Also, if you need a SCM module I have one out of my 2002 Yukon Denali I'd sell for what I paid for it ($90 shipped) but check the p/n first. Mine's 15081997. I went through the same thing as you and found out the SCM wasn't the problem. I tested this one and it works.