Does anyone know the lr3 wiring for suspension well enough to explain a few questions? Few days back my suspension gave me a fault. Compressor will not start automatically but will run if I jump the relay. However even if I jump the relay I am still dropped. I have right front sitting on the tire left front is down but not completely. Right rear is about the same as left front and left rear is up but with no air in the bag. So I am thinking there is something electrical that is not opening creating my problem. Anyone with a idea? I have a wire diagram.

 

Do not jump the relay.

Doing that runs the compressor into a closed system that will destroy your dryer in a hurry.

You have a hard fault, and it is not going to try to do anything until that fault is cleared. You can try a hard reset on the battery to see if that helps at all, but chances are you are going to need it hooked up and diagnosed.

 

Ok good to know. I did try have battery unhook but didn't help, in my mind I thought there is something not opening the circuit. Will putting air directly in the tank lift my 3 back up so I can at least load it on a trailer?

 

Probably not.

If it is faulted to the point it won't try to run the compressor, it also will not activate the valves.

What exactly is it doing when you start the truck, warning lights, messages, chimes?

 

Yellow light comes on with suspension fault after 5 to 10 seconds. Turns off the terrain control as well.
I had a compressor fail back in December and between then and now its been working great. A week ago I thought maybe right front wasn't coming up but at the time never really thought about it. Then last Monday drove it in the morning parked for a few hours and when I started it light came on and I had to limp home. So I am not positive how long the compressor may not have been working. I have a scanner tomorrow that I will plug in and see from that.

 

If the compressor is not running during those 5-10 seconds, and you are jumping the relay through the relay(as in not bypassing the fuse) I would start by swapping relays and see if that makes it run on its own.

 

I did the relay swap with no result. I know that f3 fuse is not getting power so that's why I jumped relay just to see if compressor ran. So what I need to find where or what is the switch to the relay. Judging by the wire diagram could be few things. I wish following wires in the truck was as easy as the diagram.

 

Relay is controlled by the EAS ECU. But also monitered by the EAS ECU. Fuse 3 is the supply back to the ECU that lets it know if the relay has power passing through it. Have you checked the j-case fuse? Did you jump the relay from one pin to another, or just battery to output?

The system will also fault if the compressor runs when not commanded.

 

If you are meaning the cabin fuse box by J case yes I did. So unless there is a fuse not marked I think all are good. I jumped from pin to pin long enough to hear compressor, no sparks or heating in wire so I am sure there isn't a direct short.

 

J-case fuses are the ones that look like a box with a clear top, rather then a normal fuse, often over looked. But if you went pin to pin then that is fine, and the system is not trying to command the compressor on for whatever reason.

It could be many different things causing this, fault codes will determine in what direction to move forward.