Odd. Not sure how the plug itself could create the noise. And those wires are pretty much command wires, meaning they energize as required by the EAS module, they don't normally carry any power as far as I know. If you are handy with wire repair you could cut wires one by one until the noise stops. Quick and dirty method to see which component within the compressor is causing the noise. My guess would be exhaust.

The only other things that normally make a hum would be the valve blocks. When operating they hum since they contain energized solenoids. Maybe instead of disconnecting the compressor connection, disconnect the center valve block. Maybe its actually the center valve block humming and maybe its wired in some weird way where cutting the compressor connections also kills it? (random guess).

If it appears to be a wiring issue, the next step could be pulling the wheel well liner on the driver side and inspecting the harness that lays onto the frame horn. Depending on the year the horn is removable which makes examination much easier. Here is a briefing that sorta touches on that issue. Just tossing this into the mix incase you run out of things to check.
https://landroverforums.com/forum/lr...t-fixed-98514/

 

Hi all, massive progress today! Couldn't wait to get on here and share. I've been putting LOTS of hours into troubleshooting these last few days, wouldn't be able to do this without the current crisis keeping everyone on lock down.

I opened up the driver's side wheel well and inspected the wiring and air lines. Everything looked fine. I soap sprayed the crap out of everything (shocks, valves, lines, compressor, reservoir) again and again. Nothing. Dakota, researched the 6-pin connector and found it goes to the exhaust as you suggested; as well as compressor temperature, and motor temperature.

I ran lots of diagnostic tests with the GAP tool, just sat there forever and kept watching numbers, picking what I thought was relevant, and starting the system over again and again, looking for patterns of what's right and what's wrong. I've been chasing so much and making so many corrections I was getting lost in the sauce with all the changes. Thought I found it when the reservoir pressure sensor supply voltage was showing 4.91 volts, figuring it should be 12v then looked up it's supposed to be 5v (hope this saves someone time).

HERE'S THE BIG LESSON: The FAULTS: C1A1364 was saying pressure is not decreasing when venting the gallery and C1A36-01 saying there was an exhaust valve failure. WHERE WOULD YOU PUT YOUR ATTENTION? So did I. However the pattern I observed was the compressor would run forever and bring the PSI up to 245psi then the compressor at around 270-280 F (within it's normal range) would shut down with a healthy quick exhaust sound. The gallery pressure would drop down to 50psi (The GAP now showing the gallery line pressure and not the reservoir itself) and it would eventually go down to the mid-40's after 5 minutes and then the compressor would kick on again and show the reservoir pressure in the high 180psi's. Cause and Effect, computer was telling me exhaust problems because the compressor was hotter than it's supposed to be, thinking it's not doing it's job of venting properly or a clog somewhere. But if that's not it, why is the compressor running so much when there are no leaks. The reservoir tank pressure showing a lower number when it would start back up is what stood out.

So I dropped the tank; disconnected Fuse 26, (2 bolts in front, 2 in rear, pry rear tab out and drop it onto a jack), then slowly removed 12mm voss connector waiting for air to slowly leak out and no air ever came out! When the reservoir tank was on the ground I reconnected it to the system and started it up. The big change is now you can see the weld seam that is usually against the body and the top side. Sprayed it and immediately found an air leak directly on the seam. I reveled in the moment, wow it felt good.

 

Here is a 3 second video of the leak.

 

Glad you found a leak, that is never good. But I am not sure that explains all the other issues. You can operate the system with no reservoir if you can cap it good enough (250psi is a lot, more than most comprehend). I am not sure if the system will attempt to fill the reservoir and the bags if its commanded to increase height, it may keep the center block closed until bags are at proper height then switch to filling gallery pressure to load the reservoir. At least that seems to be what I observe after filling an empty system. FYI you can either repair the tank, which should not be hard with a skilled welder, or replace it for about $120 new. Either way, get it fixed and update. Maybe that leak was really that bad that the system inferred it had to be exhaust related. I mean the logic in it is not really designed to think the tank will rust a hole into it.

 

Copy all. Was thinking about connecting my Dewalt compressor tank to the LR3, I have a perfect female end the voss connector can safely tighten with, and see what happens. I have a Lincoln MP210 welder but will buy a new tank as this thing is pretty beat up. It'll be cool to have a perfectly (for now) functioning system but advice from a reputable Land Rover source that trained me in Mobility operations said for reliability it's best to just run short lines from each shock independently with a schrader valve and inflate to desired psi from an external source. You tell the LR3 it doesn't have a compressor anymore through the GAP tool or Atlantic British flash and retain the ability to use off-road modes. I can always use the reservoir for on board air, etc.

 

Dakota you are right, it seems this was not the source of the gallery pressure not decreasing when venting gallery.

So I connected my Dewalt compressor to the LR3 reservoir line to act as a substitute for testing purposes. Started the LR3, compressor kicked in then stopped a few seconds later, holding gallery at 110psi, the GAP tool never gave a display under the reservoir section as I surmise the air never went passed the check valve in the line on the compressor, so I effectively capped it off. Stopped and started the LR3 a few times, compressor never turned on again most likely because it was happy with the gallery pressure. tried to lower the LR3 to access height then orange suspension light came on with the C1A13-64 (gallery pressure not venting). Then I heard the hum sound again, which is coming specifically from the exhaust portion of the compressor, not the connector plug as I had mentioned, and stops when I disconnect it of course. I've included a short video with the sound bite for those that are interested. I wonder if in all this troubleshooting with my new compressor installed I already blew it up? I have had it running for very long periods of time testing everything out. Also wanted to mention that when I went to disconnect the dewalt from the LR3 with the 12mm wrench turning slowly there was zero pressure in the line which I thought was strange because it was saying 110psi as gallery pressure.

 

Pic of the Dewalt compressor line hooked up to LR3 to cap off the reservoir for testing the rest of the system.

 

There is no reservoir sensor for pressure, only gallery. And makes sense that the compressor did not run long because indeed there was no reservoir to fill. So when the center valve opened up to fill it, well that was that.

Would indeed seem its the exhaust valve for some reason. Just so odd it would continue to hum after the system faults, it should totally shutdown.

 

You said you checked all of the valves already, but I would look at the distribution valve by the compressor one more time. It is just in front of the compress and the noise from it could sound like it is coming form the connector.


Jeff

 

Thanks Jeff,

I'll give it another look, or "listen" more accurately. When I'm hearing the humming sound from the exhaust side of the compressor if I touch it I can feel it being active, the compressor isn't running mind you as the vehicle is turned off, but it's "alive" I can feel the humming inside like it's trying to do something. Guessing either something inside the compressor is physically broke and not letting it happen or there is some electrical deficiency somewhere upstream. I've attached a diagram from the wiring from the compressor 6 prong plug. Not my style but I've purchased a cheap center distribution valve off Ebay just to see if it's the pressure sensor or something in there. I know how picky these rigs are but don't have the money for a genuine part at this time; if this by some chance ends up working or changing the diagnosis I'll buy a genuine part for longevity's sake. I may also return the compressor for a replacement to see if something went sideways with the install and use of this new one.


LR3 Compressor 6-pin wiring