Just purchased an LR3 for a project and dealing with suspension issue first. Vehicle has been sitting on the stops for a few weeks, connected my GAP and cleared faults to check if the compressor would run, which it does, but after about 30 seconds fault code "C1131-92 (AF) Air supply - Component failure - performance or incorrect operation" is thrown and compressor shuts off (see video for live values). I'm going to go hunt for air leaks, but wondering if anyone has a better understanding of the live values from the video and would suggest starting somewhere specific ... compressor dying, a certain valve block etc.

Thanks in advance.

 

I doubt there is an air leak in the gallery, those pressures are really high and odds are the compressor itself it venting out the excess for protection which is why you see it drop so fast. So if anything, there *might* be a blockage and it could be in the dryer assembly of the compressor if it was compromised with water ingress. Or the valve blocks at front/rear are stuck and not throwing a code yet. The first thing I would do is disconnect the output at the compressor and see if air comes out of it. Then disconnect at the front and rear blocks to check again.

The basic design is there are three valve blocks. Front and rear are not the same but looks the same. They control air into and out of the struts. The center block doe not control air front to rear as some say, it only controls air in and out of the reservoir but it also has a pressure sensor that read the gallery pressure, not the reservoir. The gallery is all the "space" from the compressor piston to the front and rear blocks. Basically the pressure in the air lines.

Do you have ANY other faults codes related to EAS?

 

No other faults listed under suspesion. Just some nuisance codes to replace rear parking sensors.

I will try the dsconnection as you've recommended and see what happens, thank you.

 

Finally had time to work on things a bit. Disconnect the compressor and I do feel air coming when I activate the compressor. What kind of flow or how much pressure should be coming from it?

Will attempt to reconnect and check at valve blocks next.

 

Max pressure is about 300psi before the compressor blows off. Working pressure though should be no more than 250psi, less with a software update. There is no way by feel to get an idea of what it is doing. You can check live pressure with the GAP tool which may help.

 

I reconnected the compressor and the Gallery pressure slowly started to rise, but no change in suspension height. I think it probably went up somewhere between 520-600kpa (I switched away from live view), it then threw the following fault code-C1A20-64 (AF) Pressure increases too slow when filling reservoir - Algorithm based failure - signal plausibility failure. No other suspension fault codes shown.

 

It has to reach a certain pressure before it will allow anything to raise, I think at least 100psi. Because if that does not happen then in theory the truck could drop a little. The only thing you could try next would be to create some sorta DIY pressure gauge setup with push connects and 6mm OD (1/4" is close and may work) hose. With that you could test the compressor output pressure. It will climb FAST with no where for the air to go and the compressor will blow off to protect itself. That is assuming it can even build pressure.

You could also make an assumption that the exhaust port on the compressor is stuck open and simply replace the little bits. Cheap and really easy to replace: https://www.ebay.com/itm/163541858300

Basically we need to figure out the performance of the compressor or if you have a big air leak. To me it would lean towards the compressor. The exhaust port can be just one of several issues though. The dryer, the thing you are pulling the lines out of, could be clogged up. If that happens then you usually hear the compressor start and "ramp up" as pressure starts to build fast though. You could also have a very worn out piston, super common. So air gets around it and can not build up enough pressure.

And there is the throw parts at it approach.... buy a new compressor and cross fingers. Could even just get a super cheap one but keep in mind they can be bad out of box to last anywhere from a few weeks to years. Gamble.

 

Can you tell if this is a Hitachi or AMK compressor?

 

Hitachi style. The easy one to take apart and rebuild, though success is never guaranteed. One BIG thing I forgot about, run the compressor and put your finger between those two line connections. That dryer cap likes to crack there, right between them. Can cause a major leak. They sell metal replacement caps. But if you feel like tinkering you can remove the compressor and open up the dryer. Best to remove it first so you do not break the fragile mount tab. Basically remove the one mount tab screw for the dryer then twist it about 90 degrees (I think) and it will pull off. Then remove the cap which will have a large spring under it and some pads that act as filters. Behind those pads are desiccant beads which should be replaced every few years.

 

Do you know what this is- is it a drain? It's hanging right on top of the compressor.