: Rear Air Suspension



slk230mb
06-10-07, 11:43 AM
I noticed that my rear air suspension isn't leveling itself anymore. I checked all the fuses and none were blown. Does anyone know which specific fuse controls the compressor? Anythings I can check without having to bring it to the dealership? When I had the truck inspected a few weeks ago the ALDL connector didn't have power and they replaced a fuse and then it worked. Could this be related? Any help is appreciated.

slk230mb
06-11-07, 12:17 PM
Bump, because I can.

hcvone
06-11-07, 01:26 PM
Steve, you have to make sure you are getting power to the compressor, and the compressor is working, you can, or someone can check that by applying power to the compressor to see if it runs.

slk230mb
06-11-07, 01:35 PM
Where is the compressor? I'd guess drivers side frame rail?

hcvone
06-11-07, 04:49 PM
Driver side rear near fuel filter if I remember correctly

Playdrv4me
06-11-07, 05:04 PM
Thats correct. By the way the ALDL is on the strangest circuit... the reason it goes dark occasionally is because its on the same circuit as the cigarette lighter socket. A very helpful member showed me that here recently.

Whats strange in your situation is that the truck isnt leveling but youre not getting the "SERVICE RIDE CONTROL" message, or are you?

slk230mb
06-11-07, 05:52 PM
Thats correct. By the way the ALDL is on the strangest circuit... the reason it goes dark occasionally is because its on the same circuit as the cigarette lighter socket. A very helpful member showed me that here recently.

Whats strange in your situation is that the truck isnt leveling but youre not getting the "SERVICE RIDE CONTROL" message, or are you?

Not getting the Service Ride Control message at all. I just know the car isnt leveling itself. Me and my dad stood on my hitch step for 5 minutes yesterday and the compressor didn't kick on. When it was working it would come on after about 45 seconds if I stood on the step.

Playdrv4me
06-13-07, 02:17 AM
Just out of curiousity, does it ride any different or sit too low when the leveling system isnt working?

slk230mb
06-13-07, 08:10 AM
Just out of curiousity, does it ride any different or sit too low when the leveling system isnt working?

I can feel that the rear is lower than it normally is. It's sitting about 3/4 of an inch lower than it normally does. It's almost riding like a fully loaded pickup truck would, which its never done before because its always leveled itself out. I really need to crawl under there and take a look.

Playdrv4me
06-13-07, 11:54 AM
Youve got a few miles so your pump may have gone kaput, but I have a feeling theres an electrical connection that worked itself loose somehow. The fact that the "service ride control" message is absent is really really strange however.

slk230mb
06-13-07, 12:57 PM
Youve got a few miles so your pump may have gone kaput, but I have a feeling theres an electrical connection that worked itself loose somehow. The fact that the "service ride control" message is absent is really really strange however.

I'm hoping it's a loose connection myself. I'd like to avoid any major repair bills if I can help it. I've got 90k on it now, I'd like to see it through to 100k before I think about replacing it.

Playdrv4me
06-13-07, 03:30 PM
If I get a chance Ill disconnect the pump on mine tonight or tomorrow and see if that causes the message to come up, then Ill try pulling the fuse. If Im able to make it warn me with both of those then it may well be the pump is just worn out, but functions electrically enough for the computer to "know its there" and think its working.

slk230mb
06-13-07, 06:35 PM
Thanks. If you figure out what fuse it is, let me know. I just checked them all (or I think all of them) one by one. Nothing in the manual jumped out at me as being for the compressor.

cadillac_tech
06-14-07, 01:29 PM
Fuse is STUD#1 underhood elect center - 40A maxi fuse.
ESC module does not monitor this part of the circuit so you'd have no message. Your compressor is probably shorting out when it gets heated up and then blows the fuse. Replace the compressor and fuse.

slk230mb
06-14-07, 01:33 PM
Fuse is STUD#1 underhood elect center - 40A maxi fuse.
ESC module does not monitor this part of the circuit so you'd have no message. Your compressor is probably shorting out when it gets heated up and then blows the fuse. Replace the compressor and fuse.

Thanks, I'll check that when I get home. Any idea on how long the FSM says a compressor replacement should take?

slk230mb
06-14-07, 08:24 PM
I crawled under the truck, the compressor is shot. I pulled the plug going to it and it's getting power. The fuse isn't blown. It looks like it's a PITA to replace on the ground, I'll probably take it to the dealership.

wookerNokturnal
06-14-07, 08:28 PM
Steve, you have to make sure you are getting power to the compressor, and the compressor is working, you can, or someone can check that by applying power to the compressor to see if it runs.

i agree with him double check it!!!!!
it could be a simple problem

cadillac_tech
06-15-07, 01:21 AM
If you're sure the compressor is not running and the fuse is good, and you have power at the connector, I see no other option.
Compressor is behind the LR wheel. Disconnect the air line, filter line, and connector (not necessarily in that order). Three nuts at the inboard side of the frame hold this on (through holes in the frame) - 13mm socket. Thirty minutes time in your garage/driveway.

Playdrv4me
06-15-07, 10:41 AM
Steve I dont think these are real expensive on Ebay in case for whatever reason you get a hard time with the warranty. You shouldnt have any problem though.

slk230mb
06-15-07, 10:44 AM
Steve I dont think these are real expensive on Ebay in case for whatever reason you get a hard time with the warranty. You shouldnt have any problem though.

My warranty is gone and expired. This is all out of pocket. The mechanics in my area charge comparable per hour rates that my dealership does, might as well get it done by someone who knows these trucks...

Playdrv4me
06-15-07, 10:53 AM
I hear ya, just seems this one is easy enough to do depending on what labor rates and parts prices youre looking at.

slk230mb
06-15-07, 04:00 PM
If I had access to a lift I'd do it myself in a heartbeat. Laying on my back under the truck trying to replace the compressor doesn't seem like a fun way to spend a couple of hours. I'll get an estimate and see how much it'll run me. Anything more than $250 and I'll suck it up and do it myself.

slk230mb
06-20-07, 03:02 PM
Well my truck is at the dealership getting the fuel filter and rear pads and rotors replaced and they quoted me $400 on the compressor alone. I'm going to see if Lindsay can get me a better price and then I'll replace it myself.

escalade2626
09-24-07, 10:33 PM
im having the same problem, i had my truck lowered, then service ride conrtol light came on. they replaced one shock still didnt work, took the lowering kit out and its still sags in the rear and it wont turn on been at dealership
5 times still cant fix it
should have bought a range rover!

ZX_man
03-25-08, 03:40 PM
Any update on the compressor issue? I noticed mine is not working either. I'll have to check the items that caddi tech said to look at. Funny my 02 is also Aspen white....maybe its the color : ) Only difference is that I have near 145K on mine.

Walter

dstinson
03-25-08, 11:56 PM
same thing is happening to me, i donít have any error messages but the other day I was towing a 3000 lb load, I had to move some of the load off the tongue of the trailer because my rear was rubbing (already have it dropped). That was the first time i hauled a load that size so i have yet to figure out what the problem is. I will check power first, then fuses.

EXTodd
06-14-08, 10:39 PM
My air ride control compressor on my '02 EXT stopped working Memorial Day Weekend when I was camping across the mountains. It wasn't a problem getting the boat back over the mountains and home which was about 170 miles. But when I got home I had to have my friend pull up hard on the tongue of the trailer to disconnect my boat and click the trailer wheel down. I am not getting "service ride control" in my message center and the air bags have not lost any pressure thank God.

Me and my buddy disconnected the compressor and put a test light up to the plug but we could not get any power. I started the truck up and stood on the bumper to try and activate the compressor. Is there a actual physical switch that activates the compressor (opens up power) or is there constant power to the unit? I'm thinking that the physical switch may have been damaged because I was loaded pretty heavy? Is there a relay switch that may have gone bad?

Thanks for your help.

EXTodd
06-14-08, 10:50 PM
If I had access to a lift I'd do it myself in a heartbeat. Laying on my back under the truck trying to replace the compressor doesn't seem like a fun way to spend a couple of hours. I'll get an estimate and see how much it'll run me. Anything more than $250 and I'll suck it up and do it myself.

Actually the compressor is really easy to get to. You don't need a lift. Just put down some cardboard or whatever and you can replace it in 15 minutes. Easy job.

slk230mb
06-15-08, 04:38 PM
Actually the compressor is really easy to get to. You don't need a lift. Just put down some cardboard or whatever and you can replace it in 15 minutes. Easy job.

I don't know why I never updated this thread a year ago, but I ended up doing just that. Got the compressor from Lindsay Cadillac and replaced it myself. It ended up being a really simple swap.

EXTodd
06-30-08, 03:29 PM
I don't know why I never updated this thread a year ago, but I ended up doing just that. Got the compressor from Lindsay Cadillac and replaced it myself. It ended up being a really simple swap.

Good to hear bro. I didn't want to see ya spend lots of $ on something that was such a easy DIY.