Vag Com wheel speed , measuring block ,shows 1 wheel spinning faster than the other 3

[shaper]

Hi Folks as the title states i have a ongoing problem with my audi a2.

I have the red (!) warning light ,and 3 beeps sounding when i accelerate past 20mph ..I have scanned the car using a fully registerd ross tech hex-usb can cable.and recieved the fault..


Address 03: ABS Brakes Labels: Redir Fail!
Control Module Part Number: 8Z0 907 379 D
Component and/or Version: ESP FRONT MK60 0101
Software Coding: 0007303
Work Shop Code: WSC 00000 785 00200
1 Fault Found:

00285 - ABS Wheel Speed Sensor; Front Right (G45)
003 - Mechanical Failure


I have since changed the wheel bearing complete with hub ,and the speed sensor..(all new)

I have also done a speed rolling test ,using my ross tech interface..

the Vag scope is showing that 1 wheel is spinning slightly faster than the other 3..I assume this is the cause of the red warning light and 3 beeps..

Is there any other way of sorting the problem out please thanks..

[a8 tech]

check the resistance in the wiring to the front right as the loom chafes on the strut.The loom can be replaced and spliced into the abs control unit quite easily, as this will flag up as a mechanical fault because the air gap will increase from the sender to the rotor wheelAttachment 7616

[shaper]

Thanks for the quick reply a8 tech..I have checked the cable connected to the speed sensor carefully ,and there are no splits..

One thing i would like to add ,is my near side front brake ware sensor cable is damaged ,and i have taped the cable back together ,the yellow warning low pad light no longer comes on..

could my botch up of this cable be affecting the speed sensor reading?? thanks

[a8 tech]

Possibly but if you can run a dummy loom along side the existing loom taking into account the wiring may be screened to prevent interference.I wouldn't repair any breaks with this type of loom as its screened so the new loom for the nsf may be the answer and not uncommon to A2.
If there is no damage to the rotor or the sensor then its either the loom or the abs unless the tyre size differs

[shaper]

Thanks a8 tech.If I replace the loom as needed. And I still have the fault, is there anyway I could reduce or increase the air gap either by Vag Com or physically adjusting the speed sensor against the rotor. I.e. slightly pulling it out...

Regarding the abs if there was a fault with it, would I still be able to fully communicate with it, using my interface?? Thanks

[a8 tech]

You can't adjust the gap as such because the abs has pre determined maps for wheel speed etc so it would be unwise.You can communicate with the sensor but via the abs controller but the signal returning from G45 is corrupted hence the wheel speed rpm is out of spec which can be caused by the ring gear moving or a worn wheel bearing.Electrically the resistance may be above the 0.3 ohms which will then read incorrectly and the signal will distort as this will be hall effect so the square wave will be noticeably smaller which could be confirmed by using a oscilloscope.

You have identified the problem but I feel you need to eliminate the mechanical side by checking the wheel bearing and the ring gear for movement as well as the fitting position of the sensor.

You could then test the gap by disconnecting the abs connection at the sensor and connect the oscilloscope and rotate the wheel whilst observing the gap, then reconnect the abs circuit and again connect the oscilloscope and test again at a similar rpm to compare to determine the cause or eliminate this side leaving only the abs controller.

[shaper]

Thanks i will get the loom replaced 1st..the wheel bearing came as a full kit including hub a rotor ring and was only fitted 3 weeks ago and the sensor 1 week ago...

I`m gonna have to get it booked into a garage to get the sensor checked using a oscilloscope..

Thanks for your time and valuable info a8 tech much appreciated

[spottedhaggis]

I have same issue, just changed the hub and wheel sensor with the same error coming up.

With regards the sensor, we noticed when changing it there is nothing that suggests it goes in a certain way or possition, just seems to push hard into the hole, is there anything specific we should know about putting the sensor in, a certain way etc, or is it simply push it in make sure it is in fully and plug it in.

Also, we unplugged the sensor but the VAG com did not mention anything about the actual sensor being missine, just came up with the same fault

Address 03: ABS Brakes Labels: 4B0-614-517.LBL
Controller: 4B0 614 517 G
Component: ABS/ESP front 3428
Coding: 06399
Shop #: WSC 02325
1 Fault Found:
00290 - ABS Wheel Speed Sensor; Rear Left (G46)
30-10 - Open or Short to Plus - Intermittent

Should the system recognise when the sensor has been disconnected and tell me its not there?

[shaper]

Hi spottedhaggis

How i managed to sort my problem out, was to adjust the depth i pressed the sensor in, until the red warning light went out..The error above, that you are getting on your Vag Com, was one that i was getting, when the sensor was not connected to the loom, so that error would be correct..Also you have not stated which wheel, n/side or o/side, and are you sure you have the correct sensor for that wheel?..I`ve recently change my passenger front bearing and had to buy a new sensor, and on 2 occasions the company sent me the wrong sensor..ie i needed a o/side and they sent me a n/side..also bear in mind the wrong sensor will fit in the hole but will run in reverse to the others and will throw out errors..hope this helps

[spottedhaggis]

Its the rear passenger side, and I have the right sensor, in fact I now have 3, the old one (possibly not faulty) a cheap ebay one, no clue if it works or not and a proper expensive Audi one.

Today we played with the sensor, and eventually we unplugged the ECU, left it off for about an hour to reset the computer, ran a VAGCOM, cleared the old error code, ran it again, no errors.

Took it for a test run of around 5 miles, no lights on dashboard, did a brake test in some gravel, ABS worked perfectly. Got back, did another read no error.

Drove home, ten miles floring it, cruising slow, braking on and off, on bends etc, doing anything I could to cause the fault, got home, no lights on dash no fault in software. I think maybe the computer simply needed a reset.

Before this, if I cleared the codes, and started the car, engine could be cold or fully warmed up, made no difference, as soon as I moved forward a few feet the dash lights would come on and the same sensor code would appear, tonight after ECU reset no codes at all. 15 miles later still no codes, so I think thats what fixed it in the end.