P85+ Air suspension stuck full low

[The4ork]

Suspension is stuck full low. Manual adjustment just gets the spinny wheel thinking symbol but does nothing.
I've done 4 button resets and power off's multiple times.
Tried swapping relays.
Service mode provides no information on the suspension alerts.

Today i pulled the entire frunk out to make sure the air compressor kicks on - it does.
I've also checked for any audible leaks - i hear none
Tank is holding pressure in the 80PSI range. I tried pumping it up to about 115psi but when the car powers on, the compressor kicks in, and it drops down to the 80-90psi range.

I did come up a little bit, it seemed bottomed out for a while - i was unsure if the compressor was even working at all - but it seems to come "up" to the "lowest" setting but wont adjust from there.

Red suspension light comes and goes. currently on.

I'm running out of DIY troubleshooting. Can anyone suggest some other things to try? this is a 2014 P85+ out of warranty so anything i can do myself is preferred - i'm an experienced mechanic with minimal tesla experience.


Thanks!

 

[DerbyDave]

Try enabling jack mode or tow mode to see if anything changes.

 

[dwbv]

I assume it's still MCU1? The car still drives fine? I'm thinking it may be an MCU issue wherein the hardware is failing to submit the command via software appropriately? If all compressor components check out and there are no service errors then it's gotta be a software issue.

You're simply not able to tell the compressor to raise the car since the MCU does that; and for whatever reason, it's failing to do that.

 

[NewbyMaybe]

Did you disconnect the 12v and fireman's loop reset?

 

[The4ork]

Did you disconnect the 12v and fireman's loop reset?

I disconnected the entire positive terminal on the battery

 

[The4ork]

OK so here is the update. all of the sudden it started working again for a week or two. Then out of the blue i got the red unlevel light again in the dash. It seems it disables the suspension leveling all together and eventually it just gets lower and lower. Last night i noticed my wheels were scraping in a turn. luckily it was the last turn before i got to my driveway. The front bumper is so low my foot barely fits under it. I cannot get a jack under it at all.

I just ordered all new level sensors front and back. I'm going to start there. If it still persists i may try the solenoid block.

fingers crossed but this thing is stuck slammed to the ground again after several resets and pumping up the tank and bleeding the tank. Its hot as hell out right now so later tonight when it cools down i'll disconnect the battery. This is more of a pain in the ass as it sounds because you have to remove the plastics and the cabin filter housing.

 

[NewbyMaybe]

Did you spray soapy water or leak detector on the system? If there's no leaks then the compressor must be worn out.

 

[NewbyMaybe]

A wheel configuration reset is easier than disconnecting the battery.

 

[The4ork]

ok another update. I replaced all 4 level sensors. I figured since the car thinks its not level it may be a sensor.
I've done a wheel config change a couple times now and i cant get it to raise in my driveway. It is still stuck full low and wont raise enough for me to even leave my driveway without severely scraping/damaging the front bumper.

what part should i replace next? the solenoid valve block?

I've verified the compressor runs and it pumps the main tank up to around 80 PSI. What is the working pressure on these?

 

[Doanster1]

Tank takes well over 80psi. I’m thinking, as in a majority of the cases here, that it’s the compressor. There are pressure sensors inside the compressor. Also, it can seize even though it runs for a short time. Unfortunately it’s the most expensive part.
If you want to try the valve block first, I have both a new aftermarket one as well as my stock one. I bought it/swapped it in when I had SAS issues, but the compressor was the culprit. (Long story, read my old threads for the gory details.)
PM me if you want to try. No charge.

 

[Gtech]

ok another update. I replaced all 4 level sensors. I figured since the car thinks its not level it may be a sensor.
I've done a wheel config change a couple times now and i cant get it to raise in my driveway. It is still stuck full low and wont raise enough for me to even leave my driveway without severely scraping/damaging the front bumper.

what part should i replace next? the solenoid valve block?

I've verified the compressor runs and it pumps the main tank up to around 80 PSI. What is the working pressure on these?

Did you checked service mode for any hidden errors?

 

[The4ork]

Did you checked service mode for any hidden errors?

I did, but i dont see anything pertaining to the suspension

 

[The4ork]

Tank takes well over 80psi. I’m thinking, as in a majority of the cases here, that it’s the compressor. There are pressure sensors inside the compressor. Also, it can seize even though it runs for a short time. Unfortunately it’s the most expensive part.
If you want to try the valve block first, I have both a new aftermarket one as well as my stock one. I bought it/swapped it in when I had SAS issues, but the compressor was the culprit. (Long story, read my old threads for the gory details.)
PM me if you want to try. No charge.

Have you swapped one out? Its probably way expensive from Tesla, but what about some of the aftermarket ones?

 

[Doanster1]

Have you swapped one out? Its probably way expensive from Tesla, but what about some of the aftermarket ones?

I’ve swapped the compressor out multiple times now and do not recommend remanufactured ones that are also compatible with Audi. At least not one specific brand. I had two fail on me back to back. Went OEM and smooth sailing after that. It’s ~$750 from Tesla so yes, expensive. You could pick up one off eBay if you want the risk.

 

[The4ork]

OK, guys new update. I just replaced the air compressor and i cannot get the thing to come on. I thought maybe it was faulty so i plugged in my old one and it doesn't kick on either. I think there was possibly nothing wrong with the compressor and whatever commands the thing on is faulty. I've tried pumping the tank to 120 psi, and I've tried it at 0 psi. Hard resets etc (wheel config change) and nothing. Tried manually setting the heights. Tried swapping relays, but nothing. I've checked every fuse with a multimeter all good.

So far I have changed all 4 sensors and the compressor.
Is it the valve/solenoid block that has the pressure sensor in it that commands the system on?
What would prevent the pump from coming on?

Maybe this is the problem I've been having all along and not it's just 100% dead whatever it is.

Thanks

 

[The4ork]

I found this interesting writeup on the valve block:

Defect symptoms and diagnosis​

Over time the solenoid valves in the valve block can become sticky or blocked by small particles that have circulated through the system when operating.

For example, when an aging compressor breaks down, the valve block can consequentially become damaged too.

Due to overheating, small metal particles can block the solenoid valves and disturb the air distribution. Symptom: the vehicle is lower in one or more corners.

This symptom could also occur when there is a leak in the air spring.

Fortunately, the actual cause can be easily identified by swapping the concerned air line in the valve block.

If the valve block is the issue, the problem should then move to another corner.

If the problem stays on the same side, it is indeed an air leak.

The valve block is also involved in the release of excessive air pressure. If needed, the solenoid valve towards the air compressor is opened.

The pressure is then released through the pressure release valve on the compressor.

Thus, in case a vehicle stays “locked” on a certain ride height, first check the functioning of the pressure release valve on the compressor before diagnosing a faulty valve block.

If an air compressor is no longer running, the usual suspect is often the compressor itself or a faulty relay.

But it might just be the valve block.

The air suspension pressure sensor is located inside the valve block, not in the compressor.

If this sensor isn’t working correctly anymore, the signal for activating the compressor stays out and pressure is no longer built up.

If the dryer no longer has the capacity to keep moisture out of the system, the valve block can corrode internally.

Additionally, when the outside temperature drops below zero degrees Celsius, the moisture inside the valve block can freeze causing it to stop functioning.

One last thing to keep in mind is that normally the airline from the air compressor to the valve block is unpressurised if the compressor is not running. This is done to allow the compressor to start easily.

If for one of the abovementioned reasons this airline stays pressurized, much more heat is built up each time the compressor is activated.

This could lead to a burned-out compressor.


So after reading the above the thing that sticks out is:

"The air suspension pressure sensor is located inside the valve block, not in the compressor.

If this sensor isn’t working correctly anymore, the signal for activating the compressor stays out and pressure is no longer built up."

I guess I'll order a valve block. Unfortunately, it looks difficult to change from above in the frunk, and the car is literally sitting on the ground hindering access from below.

 

[Doanster1]

The main 40A MIDI fuse is prob blown. Valve block is simple to swap out from above. Much easier than the compressor. Remember, I already offered to send you one free of charge…

 

[The4ork]

The main 40A MIDI fuse is prob blown. Valve block is simple to swap out from above. Much easier than the compressor. Remember, I already offered to send you one free of charge…

Is that in one of the two frunk fuse boxes? I've checked every fuse in there with a multimeter

 

[Doanster1]

Is that in one of the two frunk fuse boxes? I've checked every fuse in there with a multimeter

No. It’s the fuse box buried under the cabin filter underneath the passenger side cowl. Easy check is to check for 12V at the K11 relay that controls the compressor. That’s in the right side fuse box.

 

[The4ork]

Checked the fuses all good. Got a new valve block installed. The compressor finally kicks on!!!! Once it gets to about 90 psi I get a long PSHHHHHH From the black 'out' line from the valve block.

Still can't get the shocks to come up and I'm still bottomed out. I feel like I've replaced every major component in the system!!!!

Just rechecked for leaks for the last hour with soapy water and came up short everywhere.

I'm % out of ideas!