Driving home from work today, the air compressor for my EB did not come on. Tried 4x4 & Low. Still no compressor. Got home & disconnected the battery in hopes that the system just lost it's bearings... the CK SUSP light is not on. If the compressor stops working, should the CK SUSP light come on?

Adam

 

Driving home from work today, the air compressor for my EB did not come on. Tried 4x4 & Low. Still no compressor.
- Possible the vehicle is already at trim height, no need to kick on. You should also check the 50A fuze that directs power to the compressor is not blown.

Got home & disconnected the battery in hopes that the system just lost it's bearings... the CK SUSP light is not on. If the compressor stops working, should the CK SUSP light come on?- Not necessarily. Compressor is not designed to run full time, only in a couple short bursts to set the trim height after you start it up (if the vehicle has sat for a long period of time, ie overnight) and occasionally as you drive to keep it there (or overcome small leaks in the system as well.) Pulling the battery cable off does not 'reset' the suspension controller, only the engine control computer as far as I know. You can't trust the CK SUSP light on EB's, they are notoriously finicky wrt ride height setting, you could be 1/8" within tolerance at all 4 corners and the light still won't always come on. The light usually comes on when the compressor cut off switch gets accidentaly kicked by your front seat passenger for example. The light can also come on if the controller sees a major fault, like a leak in a solenoid or air spring, or if one of the ride height sensors is loose or out of adjustment.

- Verify the compressor can run first by applying 12v from the battery to the compressor directly. If it doesn't, then it could be the compressor. If it does, then you aren't getting 12v to the compressor for some reason in that circuit. Check the compressor relay, they are solid state devices that can also go bad, it's under the front passenger fender near the headlight. Make sure all your connections to the components are tight.

Try that stuff first.

 

Thanks for the detailed reply. I should have added that the suspension was set low and not to normal ride height. I checked as you said & compressor works, the relay has gone bad. For the time being, I am going to buy one on ebay for $50 instead of $132 at the dealer(and thats 15% employee discount). I hope the compressor/relay last till spring, then I will replace the compressor with one from American Air Suspension. Approaching 158,000 miles & still running strong. Checking the relay, I see that rust is seriously eating the radiator support near the front body mounts. Hope that last till spring also....

Thanks, Adam

 

I just replaced my relay, $140 new at dealer; my was corroded on one terminal, tried cleaning it but it was too rusted and metal was about to fail (that terminal post was about to break off.) I installed the new relay and took the old one apart to see if it was salvagable; ended up soldering on a new terminal, but I'm only keeping that one on the side for emergencies.

Rust is a huge problem on these vehicles, you just have to keep after it. I find myself once or twice per month under the vehicle overhauling some rusted area, just did the radiator support. Should have undercoated it when I had the chance when it was new, but I was afraid of even more hidden rust problems from that stuff. Check the bottom seams of your driver side doors and the passenger rear door; I had to de-rust, prime, and paint those. Its a hassle, but as long as you get ahead of the critical rust areas, it's manageable from there. I usually just have a can of 'rust reformer' or 'silver bullet' nearby when I do any repair on it these days, that way I can tackle the rust as I get to it. However, I am NOT looking forward to eventually having to replace the exhaust headers, those bolts are in bad shape.