JimmiGathu

Hi!
Got an Audi A8 FSI 2007 model. Just replaced the suspension valve block since it was leaking, but now it's gone to some sort of lock mode and has refused to lift. I've confirmed it's not on Jack mode. What could be the problem?

pelletman

What do you mean by lock mode?

JimmiGathu

It's completely refused to re-activate the suspension system. Checked diagnostics and no fault is showing

JimmiGathu

Or maybe what I should ask is, what would cause the air suspension system to refuse to activate? I've replaced the pump, full struts, valve block, relays et al!

Mister Bally

You ran a diagnostic scan with VCDS by Ross-Tech or the VW/Audi dealer $25k tool, correct?

JimmiGathu

Indeed

Mister Bally

I would say that 12 volts is not getting to the WABCO ECAS compressor. I'd verify that +12vdc is getting to the input of the "373" Relay and that the output terminal has continuity to the connection on the compressor. While in there, with the relay removed, disassemble it and verify the contacts are good and it functions electrically. You can install it partially with the cover off and press the armature that activates the power contacts and see if the compressor operates.

Heck, disconnect the power wires to the compressor pump motor and connect them directly to a vehicle battery (or a minimum 30 amp 12 volt power supply if you have) to verify the pump motor is working. Old motor brushes could be worn out but that is a rare failure mode on the WABCO air compressors.

Usually, VCDS will detect if the 40 amp fuse is blown. Perhaps a fusible link at the battery is blown that provides power to one of the bus bars that feeds the 40 amp fuse. But, some other things would be disabled in the car. Look at the wiring diagram to confirm my speculation.

JimmiGathu

Ok. Will do and get back to you. Appreciated!

pelletman

I'd put 12v to pump first thing just to see if the pump will operate, then chase wiring problems if it does. You could just have a dirty connection to the compressor

JimmiGathu

Ok. Thanks!