Hi everyone, We are Military Mobility, a non-profit that provides off-road expeditions to veterans. On the GAP iiD tool we're getting C1A00-53 (AF) Control Module - System programming failure - deactivated. The other major consistent code is C1A13-64 (6C) Pressure does not decrease when venting gallery - Algorithm based failure - signal plausibility failure.

BACKGROUND: Brand new battery, new compressor (Dorman 949-900 that is direct replacement for Hiatchi), new brake switch, bulbs good, pushed compressed air through all lines, took apart and cleaned all three valves (nothing looked off, no white powder, 0-rings seem ok), pulled fuses F3 and F26 at various heights DOES NOT LEAK AIR overnight. SYMPTOMS: Guided calibration is the only iiD program mode that will raise or lower the vehicle (LR3 will not raise or lower on its own, always triggers suspension failure). Front raises slow, about 3-4 minutes to raise it up from bumpstops, with lots of clicking coming from front valve. Here's the weird thing, often times for the front driver & passenger tire with the up and down arrows on the iiD tool, when pressing the up arrow it will lower the vehicle instead of raising it, other times it will raise it (again very slowly). The down arrow won't lower either front, just makes a electronic strained sound at the compressor connections. Front will only raise to about 21" from center hub, rears will go to 25". On the rears the down arrow will not lower, only will go up with the up arrow. Only way to get the vehicle to lower is to use the deflate all program mode. I welcome any advice, it's a beautiful vehicle in wonderful shape overall (except for this). Anxious to get veterans behind the wheel!

 

Sounds like a bad switch for one thing....and something wonky up front. Not sure about that "clicking."

 

Thanks for the reply. Please forgive my newness with Land Rovers, we're used to other brands. With regard to a bad switch what is being referred to? I had researched the brake switch can foul up the air suspension so I replaced it with a genuine part. The clicking is definitely coming from the front valve itself; don't know why but that's where the sound is originating from. Thanks again.

 

I meant the height selection switch. Maybe the previous owner left the sunroof open and it got wet, or maybe spilled on it....? That has been known to happen and cause similar issues. I would suggest changing the front valve block then. It's not a spendy job.

 

Will keep this in mind, thanks. From reading a lot of LR3 traffic it seems the standard is to just throw parts at the suspension as a process of elimination. We’re striving for a bit more understanding of our “new to us” vehicle through sound testing/ troubleshooting. I’ve already observed with this system what initially seems to be the cause is actually an effect. Someone on a post said this is because the computer system masks so many problems that when you start solving one another one shows itself. Again, thank you for the input; this helps us give some weight to possible solutions.

 

I think that's a good approach. There is a lot of t-shooting you can do for the EAS. Lots of reading on this forum and others you can do to guide you. My comment was based on what you are stating and 15 years of ownership. ....there is always something new though!

 

Can I assume you have done a hard reset of the vehicle (pulled the battery connection)?

A lack of pressure decrease is generally an exhaust fault. If you can actually here it exhaust then its likely a pressure sensor fault. There is only one in the entire EAS system and its at the center valve block. Contrary to some write-ups, only the gallery pressure is monitored. The air reservoir tank itself is not. Gallery pressure is simply the air in the lines between the front valve block, rear valve block and compressor exhaust port. It typically will bleed down over time and its actually vented before the compressor will fire up so the compressor is not fighting air pressure to start.

The center valve block only operates the reservoir tank, there are not solenoids to control air movement to front or rear blocks. I recommend making sure this is properly connected, in theory a raise command could result in a drop because when attempting to raise it is not supplied with the reservoir air as expected.

The other code is an odd one. Never saw that before. Try setting the EAS for tight tolerance if you can (this is done for calibration of heights but also for when doing alignments). If it sets, set it back to normal again.

I agree that the height switch could be faulty, can never rule that out really. With the second fault, it makes me wonder if the EAS module itself is faulty though. I would do an overall data check on what you can. The gallery pressure when the compressor is running, the height sensor values, compressor temperature... But again, check that center valve block connector (its in front of the compressor inside the cover).

 

Thank you so much Dakota Travler, this is very helpful info explained in a way that sheds a lot of light on things. I had thought the reservoir was included in the gallery, knowing the measurement is taken separately is good to know. Makes me think it could possibly be a bad center valve block sensor. I researched to remove the reservoir from the LR3 and hook it back up when its on the ground to rule out leaks on the top end seam; may due this just to rule it out.

Yes I've done the battery reset more times that I can count. I just carefully with great paranoia re-checked the routing to the reservoir valve as recommended and its correct, a real challenge to differentiate between the front valve and reservoir lines at they kind of intertwine above the frame tie-in and share very close quarters.

I will test out the EAS tight tolerance and keep the height switch in mind as well. A note to all; I will report progress through completion of repair so others can benefit.

As for the exhaust here's what I have to report; I now can very clearly hear the exhaust when the compressor shuts off. Through the GAP iiD I monitored the gallery pressure when the compressor was running, it got up to 220psi (it's supposed to rest around 250psi I believe) but when the compressor would shut off (and I would see the compressor relay very quickly flash to on & 100%) the gallery pressure would drop to around 45psi; makes sense with what you were saying about the gallery lines not fighting the compressor for when it fires back up. I wanted to wait for it to get to 250psi to see what happened next but shut the LR3 down when my brand new compressor temperature was at 273.2 F (not sure what are healthy limits). I recorded all this with the GAP iiD option. Lastly, as has been consistent for hours after the LR3 is shut off there is a very loud electrical hum that resonates out of the compressor connection. I know the LR3 has a mind of it's own and might be self balancing and all that but until I figure it out I unplugged it for preservation's sake.

 

The EAS self-adjusts for up to 6 hours after the truck is off. I think at 2 hours then at 6? Something like that. Maybe its just 2 hours. Forgetful on that.

But there should be NO sound at all from the compressor. Keep I mind the parking brake module and the rear diff are in that area. If you have an e-diff you could pull its fuse, same for parking brake. Just to rule those two causing the noise. Unless you are 100% certain its compressor related. Really the compressor should only make noise when operating, there is nothing that would really cause it to make noise otherwise. If you have the cover off you could always unplug one of the two connector for it and see if the sound suddenly stops. One connector is main power. The other connector is for operation, exhaust and temp sensor.

You may never actually reach 250psi, that's sorta optimal and due to variances the sensor may not even be spot on. But if its reading that and reading the drop that makes me think the sensor is okay.

 

Yes I have the cover off and the compressor plugs (and the center valve) hanging down low. the sound is 100% coming from the compressor plug that controls the pilot exhaust valve solenoid and temperature sensors. It's a fairly loud consistent hum. As soon as I unplug it, it stops. If I plug it back together, the sound returns in a few moments. Need to figure this one out for sure now. This could be it.