[V6-12v] ABS fix .. at last i got a brake !!

Clive Young cyoung1661 at rogers.com
Sun Mar 20 21:40:59 EST 2005


an update on the ABS situation.

Story so far .... didn't have any ABS at all during winter. Noticed no ABS sound at all and constantly locked up on ice. Found that the light bulb was burned out for the ABS in my instrument panel. Replaced it and heard ABS pump run as soon as I turned on ignition ( bulb required for circuit operation )  and again as soon a I pulled away. Once I hit 5KPH my ABS disabled light came on . 

1.    Removed rear seat ( 2 philips screws ) to get to the ABS module. Incidentally super easy if you ever want to do a good cleaning job on the seat and take it right out. 
2.    Checked the resistance of each ABS sensor  fom the connector after disconnecting from module,should be between 800 and 1800 ohms. Each one read 0 direct short circuit,( its an inductor so can fool you ) 
3.    jacked up each corner to lift and free the wheel and measured the folowing on AC setting with true RMS meter when measuring VSS ( vehicle speed sensor )  . LR 100mv when turning wheel at about one rev per second 200 mv when spinning it fairly quickly by hand. RR 200mv at about 1 revolution per second, and about 400mv when spinning it fairly quickly . RF 600mv at about one rev per second and .8-1v when spinning it fairly quickly. LF 1.2mv no matter what ......hmmm. 
4. Rechecked continuity of sensor and got 881ohms, rechecked all others and now got between 881 and 883 on all 4
5. Took left front wheel off , checked sensor and found sensor half way out of housing and completely rusted. 
6. Took out sensor and copper "sleeve " cleaned up to shining brilliance with some metal polish and slid it back into place until the rubber washer seated. spun the wheel and got about 100mv . Played with sensor to find "sweet spot' by moving sensor in and out fractionally ( was stiff but workable ). Got it to about 200mv at about 1 rev per second. 
7. Put it all back together , retorqued wheel . put seat back in . Went for a ride, and worked like a champ . 

When i say worked of course the ABS light didn't come on and the pump didn't start as soon as I pulled away ( thinking the left front was locked up  ) Don't think I'll do and intentional lockups right now . 

FYI for any one interested. 

With cable coming from the left on the ABS cable the pins are 1-18 left to right top row , 19-35 left to right bottom row 


LFVSS ( left front vehicle Speed sensor ) pins 4 and 5
RFVSS pins 21 and 11
LRVSS pins 7 and 9 
RRVSS pins 24 and 26 

AUDI 90 Quatro 

LFVSS ( left front vehicle Speed sensor ) pins 4 and 22
RFVSS pins 21 and 11
LRVSS pins 8 and 9 
RRVSS pins 24 and 26 

Hope this helps someone "down the road"

still no heat at idle .. grrrrr...... come on summer ....  


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