My suspension air compressor overheated and melted the plastic hoses. Catastrophic failure. I ordered a new compressor and a hose fix kit. I also installed a new relay in the engine compartment fuse box. After I installed it the compressor ran for 5 minutes or more, I assumed that it was filling the system. It would shut off and then start up again. I got a warning on the dash that the compressor was shutting down to cool. The suspension seemed to be working fine when raising and lowering from standard height to off-road height.

I pulled the relay so not to burn out the new compressor. I did my best to test each of the four shocks and the air lines into and out of the compressor. I sprayed each shock and connection with soapy water. I didn't find any leaks.

I measured each corner and will leave it overnight and re-measure. If there is a leak, it should show up in either the front or the back. Which fuse do I need to pull to cut power to the front and rear air relief valves?

Thanks Phil
2005 LR3 HSE HD

 

I believe it's F26, but you may have more success just removing the negative battery terminal/connection.

Did you replace the compressor with the same brand/version? If you went from Hitachi to AMK there is a software update that needs to occur.

 

I replaced the compressor with a Hitachi style. It looked just like the one that came out of the truck. It went in fairly easily, I had to snip a bit of the 10mm air pipe that comes out of the aft end of the pump assembly. I used a splice and a new piece of pipe that I inserted into the pump. I checked for leaks and found none. I pulled the relay in the engine bay fuse box, I think that it was R7. I left it overnight and checked this morning before I drove to work, measurements were pretty much dead-on where they were last night. I found that fuse number F3 controls the valve blocks front and rear. I have not pulled that fuse yet. I want to see if the truck suspension drops at all. I suspect that the pump that I pulled out overheated and then damaged the air pipes due to the heat. I don't recall hearing it running constantly before the meltdown.

(a quick note, I replaced the air compressor pump when we bought the truck with about 80k miles. I think that we bought it in 2013. I kept the pump that I took out back in 2013. It looks exactly like the one that was in the truck when we bought it. The pump itself is darker grey than the OEM pump that I installed 7 years ago).

I just can't figure out why this keeps on running. It only seems to shut down when the temp sensor shuts it down, not because the air tank or air pipe/shocks are full.

Phil

 

....just disconnect the battery, but let it sit for 15 min or so after you turn it off, before disconnecting.

 

I will give that a try, do I need to do a hard reset or just disconnect the battery? Phil

 

Turn the vehicle off. Wait 15-20 min for systems on the MOST network to go to sleep. Remove the negative battery cable. I usually put a sock over it and put it aside. That's it. Disabled. make your measurements and check them the next day.

 

Do you have any tools on hand that can read gallery pressure? By tools I mean laptop, GAP Tool, etc.

 

I have a gap tool. Phil

 

I disconnected the negative cable off of the battery. Let it sit for a few hours. I then put in the relay that came with the new compressor. It ran for several minutes and shut off. I did not get the notice on the dash that the compressor had shut down due to heat, as I did before. I then put in my old relay. The compressor still ran, seemed longer that it had with the OEM compressor. When it shut down, I did not get the overheat notice. It did seem to go on more than the OEM compressor. I have not lost any air in the system since I installed the compressor last week. That is why the compressor going on and off is a headscratcher. I will try this for a while and see how it does. It may just be an inferior product with a different pressure setting that causes the compressor to run when it doesn't need to. Phil

 

...any faults? Does it se to raise and lower to the proper height? Does this on/off cycling happen even after you've been driving for a while? ...or is it mainly within 5 minutes of startup?