Just reinstalled the SLS in my '03.

Had issues with the Arnott springs (see my other thread). Ended up switching to Dunlops.

So far the suspension seems to be working as the truck is level and doesn't deflate overnight. Should I be hearing the pump turn on and off occasionally at stops? I also hear the pump release air occasionally. I assume all of this is normal as it's constantly checking the truck's level?

However, the dash button doesn't work to raise and lower the truck. My mechanic said there are no faults showing up on his computer. All calibration and set up went smoothly and even indicated that dash button should be activated. Only thing that's happening is that there are two lights on on the dash binnacle (see my attached pic).

What could be causing this issue? Any one have any ideas?

Thanks

SLS Dash lights

 

You said that you 're-installed the sls'. Does that mean you were running coils before that? Did you tell the computer that you are running airbags now if you changed it to run the coils?
EDIT: Also check the relay was reinstalled.

 

My 2004 always releases some air from the springs once it's shutdown and the driver door closes. It doesn't release all the air or let the truck rest on the bump stops or anything, it just sort of goes from normal driving height, to something like resting height. Normal behavior.

And yeah, every once in awhile the pump will turn on as its adjusting ride height.

A little more insight into humroot's question would help too.

 

Yup, my 03 will occasionally let out some air after it’s parked, door closed, etc. I think it depends some on ambient temps, etc causing air expansion. They should hold air and not sink if left sitting even for several days. However mine will squat down to the bump stops when turned off and parked if it’s under a semi heavy load. I’m assuming to achieve a lowered stance to help with unloading? The SLS has its little surprises.
My pump also occasionally comes on a bit to adjust ride height on the fly, but not often.

 

Thanks for the replies. To answer the questions above:

Yes, one of the previous owners removed the pump, airbags, and cut some of the air lines, and then installed a 2" Terrafirma lift.

I just removed the lift (springs and shocks), installed a used pump (from my old '04 G4 truck), installed all new air lines, installed new Bilstein Shocks all around, Heavy Duty Genuine Springs up front (due to winch up front), and New Dunlop airbags in the rear.

Truck doesn't sag or drop overnight or even after a couple of days sitting. I do hear the pump running occasionally on the fly and probably upon start up and maybe shutdown. It's only for a few seconds. When it does release air, it's only for a second. It's just a quick Hiss sound which I assume is due to the system checking levels as mentioned above.

Where is the relay located? I double check to make sure it's still there. I'll also double check that the dash button is even connected.

 

It sounds like it is working fine. When I had mine installed, it did the same thing. So I wouldn't worry about the relay, it's obviously there.

You have the lights on the dash as shown in your pictures all the time?

 

Correct, system seems to be working fine but I can't control it with the Dash button.

Yep, two lights are illuminated all the time. Wondering if I need BCU or SLABS unit?

 

Well it the lights are illuminated the slabs unit is throwing a fault. Need a scanner to read it, and to confirm the reading, sensor reading, command valves open or closed.. You can review the wiring diagram and manually actuate the valves and the pump to confirm those are not your issues,

 

OK, so it wouldn't be an issue with the BCU? That's what controls the SLS, correct?

I tried two pumps already. Both seemed to work fine. If the bags are holding air, would there be an issue with the pump/valves?

 

Try reading the SLABS for fault codes before throwing parts at the problem. SLS is controlled by the SLABS, not the BCU.
The system is obviously not working correctly if those lights are constantly lit and you cannot raise the rear of the vehicle.