Niels K

Reading my fault codes of by E61 523i from late 2006, I get an error code "A3C7 Pneumatic-spring module (EHC), communication fault" under DTC section. Now I searched high and low, but I can't find any explanation for it. I guess it has to do with the air suspension - but I'm unsure. Also, I'm actually in doubt - do I at all have air suspension on the 523i?

Anyone who can cast some light on this?

seanjordan20

Looks like you have lost communication to your air supply control unit (37146784314). You may want to check it out to see if it's damaged or the cable. You my be looking at getting a new one.

It sits in the rear of the car not too far from the pump. It looks like it's on the right rear

Niels K

Thanks,

I have checked the module now. It looks spotless (both module and cable). And no moisture either. I tried to unplug and replug it again. And have reset the error codes. Now I have to see if it comes back

What would you do next?
Is it likely that the entire air suspension is not working due to this (e.g. compressor not starting etc.)? - and how would I know? I feel the cars suspension has always (since I got it 6 months ago) been a quite "hard".

kilotus

Check the fuse for the rear air suspension. 52 and 84 I believe. Next I’d check the green relay next to the two red relays in the first picture. What symptoms is the car showing?

Niels K

Hi again, I checked the fuses. They are all good. The green relay as mentioned - how would I "check" that one? Anyway, I disconnected the connector to the control unit, reset the error code. For a week (with quite rare driving) there was nothing reported in the ECU. In terms of symptoms I'm not really sure what to expect the car to do / not to do. I have always thought that it's suspension was kind of "stiff"/bumpy for a 5-series, but I have nothing to hold it against. Today I had the car on a lift for tire change, after it came down, I noticed the compressor run for a short period of time (4-5 seconds). Anyway, I decided to check the error codes again, and now the error is back. I wonder if I should just leave it be as "nothing", or investigate it further? How do I know if the air suspension is working "as it should"?

seanjordan20

How did you check for the code. Did you use INPA

Did you unplug the module to see if the pins had oxidation. The part may have just went bad and you need to replace it. The message is stating it has lost communication so I would assume it's a bad part

Niels K

Nope, I just connected the Creator C110+, it gave me the code (as seen in the photo above).

glyph

Get INPA or something to check modes- if you’re in production or workshop mode, the compressor is off. Production mode was what did it for me, though I never got the code, just noticed the rear sagging. I believe transport mode actually kicks the rear up 30mm to make the car less likely to scrape due to approach/departure angle.

edit: there’s also a relay in the circuit, so even if fuses are good, that could be a culprit. Real OEM should be able to track that down easily enough,

Alpine

The relay in question is the green one, out of the photo, OEM ref 61368373700. It'd be rare to fail by itself but if you still have the issue you can unclip and remove it and check for any signs of corrosion, burns etc. Then you can test it, you'll find tutorials online for testing 12 volt relays.