LR3 suspension down.. compressor not running.. heeelp!

[searover83]

I am sure this was covered before, but Im too frustrated to search.. please forgive me.
So since I got it uset w. 100k miles 5 months ago, it has had the 'special programs not avail, normal height only' condition. I heard it self level before, and also heard compressor pump up.

Now it's all the way down, and throws codes:

C1131 Air supply
U0416 'invalid data received from vehicle dynamics control module'
C1A20 'pressure increases too slowly while filling reservoir'
and another I cant seem to find now.. also related Im sure.

The compressor doesnt seem to be running or even trying to (no humming or heat). There's voltage on the main supply line (14.5V).

the fuses for the air suspension are all good. the main 20A has the voltage, but the 5A fuse 3 has no voltage, even w. engine running.

please help with ideas??? Thanks!
Jan

 

[bboldtiii]

C1a20 was a sign for me to rebuild compressor. Desiccant might me plugged


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[searover83]

thanks. but I dont even hear it running. not even humming. There's voltage on main supply line.. I presume it's always there, and control comes on the other connector

 

[Drome]

If all of your fuses are good and you are getting voltage its time for a new compressor. Ive seen for around 350.00

https://www.newegg.com/Product/Prod...gclid=CLnV1rKVkNICFYe3wAodJxUPLQ&gclsrc=aw.ds

 

[searover83]

yup indeed.. on of the motor brushes burnt off, even burnt the pcb base it was sitting on.
plenty of meat on the brushes.. and Im pretty sure it's already a replaced unit (since it was mounted w only 2 bolts).. So Im concerned.. maybe a leak? and/or clogged exhaust?
Thanks.

 

[Drome]

I've spent about two weeks on my compressor. Put in a rebuild kit for the piston and sleeve and rebuilt the air dryer. I get air to the rear only. I'm thinking that the compressor is past it life. Mine had only two bolts on it also. But the thing is the truck had a suspension fault on it when I bought the truck. Everything worked but the fault was NORMAL RIDE HEIGHT ONLY. So the compressor was running its little heart out for a long time. Just wore itself out. Ill find out very soon as I ordered a new one off Amazon. Got one for 250.00 dollars cause it was an open box. I'll post the results'

 

[searover83]

OK.. the compressor is in... It runs. but.. first, it ran for at least 3 mins, and the suspension didnt come off the bump stops. When I selected offroad height, it pumped up in 10-15s to full height and shut off. Then I selected normal height, and it bled out air, until it stopped at a nice leveled point. seems right. But the th compressor turned on, and wouldnt shut off. Repeat experiment.. now at normal height it shut off, but kept cycling. So now I have it at normal height, and ECU fuse pulled. We'll see if I have a leak, and how bad. But to me it sounds like a flaky sensor.. wheel, or some unloader press sensor or smthng.. Any ideas?
TIA..

 

[Mark Land]

You can test failure of the compressor alone by connecting the two-cable-connector (thicker ones) to an external 12V source. It has to run directly then.

If that works You can meassure if 12V arrive at the delivering side of the connector after starting the motor of the before parked car.

The other cables runnig to the compressor are temperature and pressure sensors
One of these cables, a thinner gray one on hitachi compressors is entering the unit beeing seAled by silocone and a rubber cap.

These sensors and their cables can, if faulty, send bach faults to the ECU of the EAS and make it not run aswell.

The system is secured by more than one fuse in the motor bay.

Did You read out Your fault list via OBD2?

 

[searover83]

thanks for replying.
The new compressor runs, but it seems to cycle up to 1750KPa (sometimes it cuts off at 1000KPa.. but I think it's transients or press sensor).. But then the pressure bleeds down to 120Kpa (thats like 15 psi).. dont believe that!!. No apparent change in 'normal' height. So hard to understand.. At 125KPa it stops bleeding.. so I dont think it's just an air leak. And overnight the car doesnt drop down. So.. weird.

Does anyone know what the 'dealer calibration' is about? what is actually 'calibrated'?
It's a Hitachi-type unit, built by Doorman.. So maybe press sensors etc are a bit off in internal resistance?
Oh.. and sometimes, on a particular drive, 'suspension fault'/yellow will come on, sometimes no warnings. And when the 'susp fault'/yellow comes on, *sometimes* when I accelerate (not decel), the 'susp fault'/red/'max speed 35' will chime , but then reset. So maybe I do have too low pressure sometimes..

I have an i930.. which works great to read error codes BTW. best 100 I ever spent

 

[Houm_WA]

Did you ever re-calibrate your EAS after you put in these new components? Or at least check the calibration? I'm not sure if this is the same as the "dealer calibration" you are referencing above, but I'm talking about the check between height sensors to make sure they are within specified limits and that their relative values are jibing.