Air Compressor Control Testing
 

I'm rehabilitating my 2008 e61 following some failures stemming from the notorious water intrusion problem. I'll be sparse on details, for brevity, but I'm happy to go into greater detail as requested. Focusing here on diagnosing a bottomed-out rear suspension.

I've replaced the trunk relay that controls the air compressor, along with the compressor control module, but the compressor isn't activating. The compressor could be shot, but at present it appears to be not even receiving an activation signal through the relay. So I'd like to test the compressor independently by bypassing the control system.

My question for the group: I want to temporarily bypass the relay by putting a shunt between blade 30 and blade 87 (see the attached diagram), to see if the compressor will activate. I assume that all I'll need is a wire of at least the same thickness as the wires connecting to the relay. Am I overlooking anything? In the likely case that my compressor is perfectly fine, I'd like to not make my situation worse by breaking it.

If I can get the compressor to switch on, my next task is to diagnose the control module and its dependencies.

Scott

https://cimg1.ibsrv.net/gimg/5series...651ce51b54.jpg

Why not just put power straight to the compressor instead of going through the relay

To be honest, I'm not sure how to do that. I'll google it, but if you have suggestions at the ready, please them my way.

Jumper wire (short) node 30 to 87 or 12V DC to Device.

A followup:

I decide to do this right, and rigged up INPA and the rest of the BMW tools software package. I went into the air suspension control section, and manually activated the compressor for just a moment or two. The compressor activated, and the rear lifted just a bit before I switched the device off. Next I need to perform a calibration.

Feeling good about my progress rehabbing this beast.

Let me know how the calibration goes. I am had the same problem ordered a new relay and EHC Module (used off ebay but exact same module/part #). Can activate and hand control the compressors in INPA and get the car to the correct height but if I try to calibrate it gives me some crazy/inconsistent values and then either wants to drop the car or raise all the way up once I start driving. Thinking the used module might be bad (sensors appear to be working) but curious to hear from someone who can correctly calibrate the EHC on a 2008 E61.