So, now we begin to think that we're insane, swapped out the pump, relay, valve assembly, pressure sensor, level sensors etc and the thing still won't work. Pump activates for a few seconds then stops, then all the valves open at the same time and let the air out of the system! We've programmed the EHC2 unit, deleted transport mode, tried the ride height calibration, done it all over again and still no luck....

Imagine the control unit inputs and outputs as follows;

Inputs:

-CAN bus lines (communication with drivetrain systems)
-K-Bus line (communication with body systems)
-Pressure sensor signal
-Temperature sensor signal
-LHF level sensor
-RHF level sensor
-LHR level sensor
-RHR level sensor
-Level adjustment switch

-Power
-Earth

Outputs:

-CAN bus lines (communication with drivetrain systems)
-K-Bus line (communication with body systems)
-Air supply pump
-Valves for shockers
-Pressure release valves
-LED lights for level display next to switch

The car when we have everything hooked up as normal behaves as follows;

Pump operates for a few seconds, only long enough to bring pressure to about 2 BAR (needs about 5 Bar to raise car)……a few seconds later all valves open simultaneously and let all the air out of the system…….a minute later this process repeats….and again….and again, indefinitely, regardless of ignition position, switch input, or anything for that matter.

If I now pull out every single input pin from the plug at the control unit (except the power and earth supply), thus isolating this system from any input or signal it behaves in EXACTLY the same way!!

Anybody with half an idea would now suggest that the control unit is at fault. BUT, we’ve tried installing a new one, programming it and testing……..same result!!!! BMW tried the same trick…..same result again!!!

The only feasible explanation is that the software which we’ve all been feeding into this thing is at fault. Highly unlikely but still possible.

If anybody has experienced this strange problem then I would LOVE to hear from you!