Audi CQ20V ABS problem

[M2ki]

If the ABS light turns on, then check if wire is still there
Use right size wire and push it tightly in the socket, to prevent it falling off.

[Tom_]

Whats the right size wire? Just enough to hold there, right?

[M2ki]

Yup

[Tom_]

OK, i try...And what u think about my pictures of ground abs? Looks little bit worst than yours

[M2ki]

Hard to tell from pics, copper turns blue over time when exposed to the elements.
Cant do any harm when you unbolt it, use sandpaper or wirebrush to clean the surfaces. Use some kind of contact grease or spray afterwards.

[piotr]

Hard to say mate.Did you ever try to bleed it properly?
Also it's strange that it was all good for long time and than it came on again.I would try to look if the wiring didn't rubbed through somewhere .

[Tom_]

I did normal bleed...from the rear, to the front...i am not sure, if there is how to bleed abs...but there is nothing to connect or no bleed...so only classic bleeding..i ty diagnostics, but when i go there, this day was no abs light on so it was clear

[piotr]

So I would say that air in the system is not the problem.More like intermittent electrical fault,bad connection.Will be a pig to find

[Tom_]

I changed brake lines, hoses and then sensors....There was no problem before i do a refreshment of subframes,and other stuff...than started it...

[Tom_]

So yesterday i was drive around and i see that when ABS icon show (ABS OFF) the pedal was softer, than when the ABS was ON. I can reset by abs button. Whats gonna says?That the problem can be a abs pump? Too big pedal difference between ABS ON and ABS OFF

[Tom_]

Does somene know how to check ABS controller, if it works well? Because i suspect ABS controller.

[Tom_]

Is that a normal thing, when i measure resistance on the sensors in connector and while i test and move with cable, it jumps from 1,8 to 5,4 and than no ressistance?

[M2ki]

No it is not normal, when you see no resitance, then there is a break in the wire somewhere.
I personally dont know any cases where the module has gone bad, yesterday i took two b3 quattro shells to scrap yard and left abs modules on the shells,.

[Nuno_Cristiano]

I had similar problem in my coupe.

I measured +/- 1.3kOhm in all sensors but if i change the steering Wheel front right sensor brake wire ( open ).

I bought a used sensor from Audi A6 2.5TDI C4 and only change the conector. Solved!

[Tom_]

I have 4 new sensors, now is almost everything good , but no problem with brake wire . Resistance and voltage while i turning wheels. I checked that ABS ecu is good and measured ABS sensors at abs ecu connector, everyrhing good.

1,168 kOhm
1,248 kOhm
1,176 kOhm
1,185 kOhm

So now i want to check ale 4 cv joints and abs ring on them, especially number of teeth and gap between them. Than i order a 2 channel USB osciloscope, so i hope, that it shows me where is problem