williebone

As some may know, I've had to Replace the Air Ride Compressor, Control Valve Unit, and Relay last Spring. Well I recently experienced and Issue with the System and the Problem is that my Yellow Lift Light is On. The Car is Stuck in the Up Position and only gives me Confort and Auto Mode Selection which to my knowledge still doesn't change anything between those 2 Options (stuck up).

I ran VCDS and got the Following:

Tuesday,28,December,2010,15:29:56:27574
VCDS Version: Release 10.6.3
Data version: 20101206

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Address 34: Level Control Labels: 4E0-910-553.lbl
Control Module Part Number: 4E0 910 553 E HW: 4E0 907 553 E
Component and/or Version: LUFTFDR.-CDC H05 4290
Software Coding: 0012411
Work Shop Code: WSC 02313 785 00200
VCID: 254AFD0D9567
1 Fault Found:
00668 - Supply Voltage Terminal 30
009 - Open or Short to Ground
Freeze Frame:
Fault Status: 11101001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 17
Mileage: 131399 km
Time Indication: 0
Date: 2010.12.28
Time: 15:27:57

I went to a Local Indy and had them Lift the Car for me so that we could Unplug the Air Ride Compressor and apply a Direct 12V Source. The Compressor Ran like a Charm with no Problems so of course I was a Happy Camper at this point and was only out of $25 for my Little Test. I then went Home and plugged in VCDS to see what Advanced Testing I could do and found the following:

I checked Terminal 15 and it had Power (Voltage). I checked Terminal 30 and it was something like 0.07 which I thouht was very Low. I then checked Terminal 50 and it was Off! Next I checked the Relay Box and it says Off! In VCDS Advanced Mode you Simply Check the Boxes next to the Items you want to Inpect and it is Displayed on the Screen. The Fuse was Checked Prior to any of this and Ruled Out!

Common Sense tells me that it has to be the Relay allthough I'm not quite sure where these Terminals are Actually Located and nor do I think that it's important that I know where they are at this point. So, being fairly educated with VCDS I should be safe in knowing that the Relay is Fried which is an easy fix since I Installed it anyway. My feellings are that I should've went OEM on the Relay and not OE allthough I was told that there shouldn't be a problem using it. Long story short is that WorldImpex is shipping a Replacement and it is OEM this time.

I'm quite sure it is the Relay and no sweat if it isn't because it cost nothing but about 15 Minutes of time to Install it. The Bigger Question is why did it Fry assuming my assumptions are correct? Besides just Replacing Relay, is there a way that a Relay can be checked to make sure it's Faulty or Not? Laters,

Mister Bally

You can check the relay for basic operation; Apply 12 volts and ground to the correct terminal to energize the coil. It should "click". When the relay coil is energized, it is supposed to close at least one set of contacts. Verify that with an ohm meter while applying and releasing power to the relay coil.

Are you certain that the 30 or 40 Amp fuse is good? It sure seems like there is no power available based on: 1 Fault Found:
00668 - Supply Voltage Terminal 30
009 - Open or Short to Ground

which is what I got when my fuse blew. Of course it blew because the pump motor was drawing too much current. When I applied direct 12 volts to the WABCO motor from a spare car battery, the insulation on the #10 wires started to smoke! The copper wire was hot. Very hot.

I also thought when the temp sensor on the compressor opens, it's like no 12 volts. They don't sell it as a spare, you need the whole compressor assembly. Or, rob it from your old one if possible.

williebone

Since the Relay is a Free Waranty Replacement I will try Plug & Play when it arrives tomorrow. I will keep your Notes for Future Reference should the New Relay not solve my Problem which I surely Hope it does.

I will check the Fuse when I Drop the Knee Panel once the Relay gets here. I didn't think about the Fuse Blowing, but not sure why it would since there was no Constant Running of the Compressor. However, I did get the Car Washed and forgot that I hadn't replaced the License Plate Lens which was wide open in the Car Wash. Not sure if Moisture had anything to do with it or not! I just remember the Relay Off Displayed during Advanced Testing with VCDS and issues with T30 & T50. My hopes are that the Terminals are after the Relay which in turn is not letting Power Thru and that this is a Simple Fix. If it isn't then out comes Bentley and I will trace the Terminals, but first I will check that Fuse.

Yup! I still have the Old Compressor for Spare Parts if needed. My hopes are to one day see if it can be ReBuilt! Thanks for the Feedback MB and much appreciation! Laters,

dsorensn

I can't comment regarding your primary issue, but regarding the reuse of your old compressor here's an trick I used with my Allroad. If the unit runs, but just will not build air pressure it is very likely that the compressor pistion ring (which is composed of a heavy duty plastic or composit material) has worn down. The fix is to either replace the ring, or what I did was to carefully remove the ring, cut out a sliver of aluminum beer can (I used a Fat Tire can) the width and lenght of the inner circumference of the ring as a shim and reinstall the ring with the shim under it. Mine Allroad compressor worked fine for another 18 months or so. It's possible that it would have lasted longer if I had used brass or other more robust metal as the shim, but of course beer cans are much more common... :-)

Mister Bally

Williebone, since you're taking the knee bar off to get at the relay and you'll be by the fuse (have a spare ready); consider replacing the brake light switch. They have a finite life and right now they are only about ten bucks at any VW or Audi dealer. My '01 Beetle uses the same part as my 04 A8L. One failure mode knocks out the ESP system. Since you'll be in there, consider replacing it. I have one ready I just need to find the time to get down there and take the trim pieces off and the darn coin tray face. One tab is cracked already on mine. I just silicone it in when I'm done.

"Laters"

Mister Bally

The typical failure mode of the WABCO electric compressor is the glue fails on one of the magnets on the inside shell of the motor. Magnet gets attached to the armature so it still spins but at a lower speed due to drag and less than optimal magnetism that electric motors need. You can disassemble it and use JB Weld on the problem magnet. Also add additional glue around the other magnet still attached. It too will fail some day.

williebone

Good to know, Glad I got a Spare, May have to Tinker with one day. Thanks

Does make sense to have a Spare Fuse so I will have to run to the Dealer and pick one up tomorrow. I haven't heard of the Brake Light Switch Issue before, but it's good to know what happens when it Fails. However, I may consider Replacing it since I'll be under there anyway and it if it's that cheap then it won't hirt. As for the Trim Piece, the Clips are Very Fragile and I too used Silicone, but I had seen Silicone in there when I originally Pulled off before. Thanks

Good Stuff to know! Thanks

williebone

It was the Fuse, but I replaced the Relay since it was Free of Charge. Took about 30 minutes @ $2.50 for the Fuse and $15 for Original OE Relay which was replaced by an OEM Relay. Thanks and laters,