Suspension faults - C112F and C1130... and height sensor issue?

[allegro]

We took our 2012 LR4 w/120K miles out in the hills yesterday. The 20 miles off road were mostly tame, but I was in off-road height the whole time for clearing rocks and getting over water bars. After 5 miles or so, I got the amber "suspension warning" light and had these codes:

C112F-72 (68) (GAP tool: "Air spring valve - Mechanical failure - actuator is stuck open") and
C1130-66 (68) (GAP tool: "Air spring air supply - Algorithm based failure - signal has too many transitions/events").

No performance issues so I carried on. We stopped after about 10 miles for a hike, and I cleared codes. On the drive out, the same thing happened.. suspension light and same codes after a few miles. In both cases, I was able to continue in off-road height and didn't notice any performance issues.

Searching around forums, I see a couple reports of compressor replacements fixing these faults. At 120k miles, seems like a reasonable thing to replace even if it's not my immediate culprit. Looking at prices from various suppliers now.

Poking around in the GAP tool, I noticed in the Height Control section that each corner shows vastly different numbers while the truck is sitting on level ground... ranging from -12 to 14 (pic attached). Is this a concern? Height sensor issue? Possibly related to these faults? Might the GAP tool suspension calibration address this?

Any recommendations for initial troubleshooting beyond pulling EAS fuse 26 and watching for a sagging corner, and putting soapy water on lines/connections in search of obvious leaks?

Thanks!

 

[ryanjl]

The height sensors often show different heights because they aren't all installed the exact same; just installed however and then calibrated for the correct ride height.

Does your 4x4 screen look okay, or is there a wheel that appears strange?

At 120k, I'd say you are overdue for a compressor.

 

[allegro]

At 120k, I'd say you are overdue for a compressor.

Absolutely.

There’s no verdict on whether current AMK vs Hitachi is preferred, right? I see FCP and RME have both in kit form that come with new mount, tubing, drier, etc. If there’s no clear winner, I’ll just go with AMK since that’s what I have now (I have the “old AMK”).

As for leaks, each corner dropped 5-10mm after sitting for 16 hours. Am I correct that this isn’t a big concern? I think I’ll go ahead and replace all four air springs in the next year, but these numbers don’t strike me as “do it this weekend” numbers. Please correct me if I’m wrong.. not interested in wearing out a new compressor!

 

[ryanjl]

Did you remove the suspension fuse or relay before letting it sit?

If not, the vehicle will auto-level itself, even when it's turned off. If one corner is leaking, they'll all go down to match the corner.

After removing the fuse, if one corner does go down, you've probably got a leaking airbag. If either the entire front or the entire rear drops, you've generally got a bad front or rear valve block.

 

[allegro]

Did you remove the suspension fuse or relay before letting it sit?

Yes, sorry I should have specified that I did remove fuse 26 in the engine compartment before letting it sit. Both rears dropped 10mm and one front dropped 5mm and the other 10mm.

I plan on replacing o-rings in valve blocks as part of this suspension maintenance - is that the typical source of leaks or are new valve blocks usually called for?

 

[ryanjl]

Normally what happens is the dessicant in the air dryer (attached to the compressor) begins to decompose and sends dust through the air lines that clogs the valves.

I've gone through all my valves and just sort of cleaned them. The rebuild kit I got wouldn't have worked for all the seals. There was no way that some of them would have fit.

 

[allegro]

Right on, I've seen you post previously about that desiccant issue and I'll give my valve blocks a look & clean. Thanks a lot for the tips.

I'll get a new compressor on the way and will report back on whether that change keeps the faults at bay.

 

[allegro]

I got a new AMK compressor in today. A couple points that could help the next person with a 2012 or older upgrading an "old AMK" style compressor:

* After cutting the compressor feed pipe to accommodate the new air link pipe, it was a pain to get the air line insert installed... eventually I pulled out a hair dryer to soften the old pipe and then it went right in.

* ECU flash: I decided to wait to flash the suspension ecu until after install just so I'd know if any new faults were coming from the new compressor install vs new software. In fact, I did get faults after firing up with the new compressor. I then updated the ECU by running the AMK flash routine, and then faults went away.

One concern/question: the relay supplied with my kit from FCP Euro has a plastic protrusion on one side to accommodate a metal mounting tab, and this prevents it from fitting in the suspension relay slot. Think it's safe to cut it off? I'm guessing it'd be good to be running the relay supplied with the kit.

 

[ryanjl]

I think the relays come with the kit because it's normally just good practice to go ahead and replace the relay at the same time as the compressor. Don't think there's an difference between an AMK and a Hitachi relay. Not sure how many actually do change it, though.

If your old relay was working, you can still run it. But I wouldn't see any issue cutting that plastic off of the new relay (just so long as they are identical otherwise).

 

[allegro]

Thanks @ryanjl - went ahead and shaved off that plastic bit and the new relay is working. Old one into the spares bin.

Only other issue I discovered as I buttoned everything up was that the hole on the bottom of the compressor mounting plate was not threaded... would need to tap it if I were attaching the bottom cover. In my case, I have old Rover Specialty sliders and so the bottom cover is omitted.

Excited to be running a new compressor - here's to the next 100K miles! Will see if the intermittent codes that spawned this thread come back next time I'm out in the hills. Thanks as always for the help!