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07 CTT, with PDCC. Never drops, no air leaking issue anyhow.
My wife told me it got some chassis error red message showing up. Scanned and found 1772/1400/2250 error. Did some search and suspect it's some valve issue on struts. So tried to lift/lower the car to identify which one is faulty. Then I just noticed the air compressor is not pumping up!
Tried to search the forum to locate fuse/relay for the air compressor yet didn't get too much info apart from some 40A fuse (13) on the main fuse board (under the seat?) and relay might be under dashboard.
Anyhow, I tried to connect the compressor to 12v and it works. Yet the power cable/connector for the compressor I connected it to a multimeter to check voltage. Which amazingly most time it's 0v, no wonder compressor is not working. However, for once or two (car been on/off for testing for many times), it got 13.Xv for short time and then reduced down to 2v yet most time it's 0v. So fuse must be good and relay could be working as well.
Now I'm not sure what caused this issue, faulty wire most time it's disconnecting?
I had an issue with compressor on my wife's 957 TT. The cables actually check out okay but due to internal corrosion they didn't work under load. It was a tedious job and requires a good auto electrician - he ended up replacing a bunch of cables on mine but now it works like a charm for a couple of years.
The ride height control module is over the right rear wheel housing. It may have been exposed to the usual cabin leaks.
The compressor relay power connections at this module are A31-Brown/White and A36-Gray. You must count the pin connections since those wire colors are shared with other functions on that module.
Check the voltage there, if good the relay or relay/pump wiring may be defective.
The ride height control module is over the right rear wheel housing. It may have been exposed to the usual cabin leaks.
The compressor relay power connections at this module are A31-Brown/White and A36-Gray. You must count the pin connections since those wire colors are shared with other functions on that module.
Check the voltage there, if good the relay or relay/pump wiring may be defective.
Many thanks Rick. I found your other post in 'Chassis System Faulty - Suspension failure' which contains the diagram. Really helpful!
I don't see any cabin leak sign and seems tricky to remove/check the height control module. Instead, I think it could be easier to check the left cockpit support relay (the red/white wire which connects to the compressor, if no power, then check the brown wire)
Also, not sure how your doing your voltage troubleshooting, but the car won't move or pump with the doors open. If you need the door to be open, you have to manually close the catch in the door the full 2 clicks. Don't forget to pop it back open with the interior handle before closing the door.
Also, not sure how your doing your voltage troubleshooting, but the car won't move or pump with the doors open. If you need the door to be open, you have to manually close the catch in the door the full 2 clicks. Don't forget to pop it back open with the interior handle before closing the door.
It was tricky, to use multimeter to tap both ground and back of red/white wire is very hard. Yet I got a jumper cable, so I connect one cable to ground and also negative of multimeter. Then its very easy to test the back of the relay panel when door is closed.
So it seems the relay 373 is faulty (which is a good thing ), it got power on grey wire yet on red/white wire there's no power (red/yellow is constant 12V which is good). I can't find another spare one to test though.
Anyhow I'm going to buy a relay. Yet just realized it's pretty expensive! Even used one on ebay gonna cost $25... I'll get a genuine one from China I think (cost $6 plus shipping). Not in a hurry anyhow.
It was tricky, to use multimeter to tap both ground and back of red/white wire is very hard. Yet I got a jumper cable, so I connect one cable to ground and also negative of multimeter. Then its very easy to test the back of the relay panel when door is closed.
So it seems the relay 373 is faulty (which is a good thing ), it got power on grey wire yet on red/white wire there's no power (red/yellow is constant 12V which is good). I can't find another spare one to test though.
Anyhow I'm going to buy a relay. Yet just realized it's pretty expensive! Even used one on ebay gonna cost $25... I'll get a genuine one from China I think (cost $6 plus shipping). Not in a hurry anyhow.
Thanks all.To help others, here's the photo of the relay panel under driver's dashboard.
compressor relay is the right one:373. Part number 8D0 951 253A 12V 40A left bottom. red/yellow is constant power red/white is connecting to the compressor grey is trigger power I think
That is a very common relay on any car with VW related electrics, chances are that there is another 373 relay somewhere in the car You can use for testing purposes so you don't have to wait for the new relay to arrive.
That is a very common relay on any car with VW related electrics, chances are that there is another 373 relay somewhere in the car You can use for testing purposes so you don't have to wait for the new relay to arrive.
Yes, it's a most common 4 pin 12V 40A relay (with resistor I believe). However, from engine bay/dashboard relay panels, there's no same type relay... maybe some same model under passenger seat but I don't want to try that hassle (also on my other car, the easy-access fuse/relay box which doesn't have same type...).
Yet I opened the relay and confirmed it's faulty. You can see the photo below.
Yes, it's a most common 4 pin 12V 40A relay (with resistor I believe). However, from engine bay/dashboard relay panels, there's no same type relay... maybe some same model under passenger seat but I don't want to try that hassle (also on my other car, the easy-access fuse/relay box which doesn't have same type...).
Yet I opened the relay and confirmed it's faulty. You can see the photo below.
Oh yes the contact looks toasty. Seems undersized for a 40A fuse.
10-16-2019, 11:34 AM
No voltage for the air suspension compressor
), it got power on grey wire yet on red/white wire there's no power (red/yellow is constant 12V which is good). I can't find another spare one to test though.
