New air compressor not working 4.8is

[jak123]

Where is the relay for the sls, or does anyone know the part #?

[we350z]

I know there are two fuses in the rear and one in the glove box not sure where the relay is but I assume it must be able the fuse block in the back.

[jak123]

My fuses are all good. I’m under the impression that there is a really some where that I hope is bad.

[andrewwynn]

I'm pretty sure the compressor will have live power right near it and a relay operates it. Verify and check for voltage both at the feed to relay and the control signal.


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[jak123]

I actually don’t have a voltage meter. It seems like what I need is to have the SLS reset for the new pump. I’m still hoping the local guy still wants to help me out if not, I will pay the dealers diagnostic fee and hopefully that’s it.

[andrewwynn]

Use the $ you'd spend on the dealer fee for a pro grade scanner and a DMM is a requirement if you want to DIY a car. Get a low end model fluke or a mid grade Klein (budget $40-80).


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[brucemillar]

1) The 4.8 should have 2 axle (twin) air self leveling air suspension.

2) When the suspension goes "inactive" so you get a message on the Display that says "Self Leveling Suspension Inactive" You need to clear that error with software before the compressor will start to pump again. That is a Safety Feature to stop the pump running when it has a potentially dangerous fault (like an overheat) or somebody's hand jammed in the suspension.

You need somebody with a scanner that can clear suspension (EHS) errors to clear down the errors to get it running. Warning: The error that you currently have may simply come straight back again if, the cause of the error is not removed/fixed. So, you need to keep clearing the error until you fix the actual issue?

Are you 100% certain that you only have rear air suspension and NOT the twin axle suspension that all 4.8's came with?

I would be concerned if somebody has hacked your suspension and fitted springs to the front? This being the case, it may well be, that the error that you have will simply keep returning and you will never get the compressor back working until you correct that. This is due to the twin axle set up having a different ECU, among other bits, from the single axle set up.

Please let us know what you discover?

[jak123]

It’s rear only, there are no air lines that go to the front. Unless somebody pulled all of them. It has the black air lines of a 2 axel as opposed to the red & blue.

[brucemillar]

Originally Posted by jak123

It’s rear only, there are no air lines that go to the front. Unless somebody pulled all of them. It has the black air lines of a 2 axel as opposed to the red & blue.

Spooky

I have a 2006 e53 4.8is, this has (as standard) 2 axle air suspension. I am not an expert here, but always understood that the 4.8 came standard with twin axle air suspension. My compressor dome is actually labelled on the underside 4.8 2 axle.

Anyway. You still have the issue that needs:

1) a scanner that can scan the air suspension. INPA can do this.

2) a view on what errors you have. Most errors will stop the compressor until they are cleared.


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[jak123]

Thank you for the responses.