[2.3 20V 7A] [Coupe B3] ABS problem on CQ20V

[bobo23]

Hi guys, i have problem of ABS light ON after some mileage. Relays is good, fuses either, new 3 abs sensors...Every sensor puts almost same resistance and while i turning with wheels, voltage is there..Any ideas? CV joints are new and abs tooth ring either...So no rust on ring













ABS diagnostic was clean - no error codes

[Jarewa]

What is the distance between the sensor and the ring? As ABS lights on when driving it must be a problem with wheel speed reading.

[Krzysiek 84]

bobo23,

_uwaga

[bobo23]

Jarewa, The gap is the same...i push sensor to the max..

Krzysiek 84, Ok, sorry, its done

[Jarewa]

It would be easiest to connect a 4 or 2 channel oscilloscope and compare the impulses. Then it came out which wheel is failing.

Although I do not want to believe that the ABS light was on and there were no mistakes then it is impossible.

[bobo23]

I know about an osciloscope, but i havent them. No on tuesday, when i drove 40km to diagnostic...this day NO ABS light at all....diagnostic was clean...
I asking if someone around Cieszyn/Tesin have a 4 or 2 channel osciloscope, but no one yet

[Jarewa]

And doesn't it always go after driving? ABS lamp.

[bloku]

At first check sensors resistance -what they showed you? Electricmeter should shows between 1100-1200. Best of it is 1150. Also You can check how much is change after moving wheels.

I had the same problem in Audi Coupe Quattro 2,0 NM (one of four new sensors broke down)

[bobo23]

It shows during driving...no before drive and no after drive

When i measured voltage on sensors...The numbers increased/decreased depends on the speed of rotating


On the pictures u can see a resistance...every sensor is around 1150-1200 ohms


3 sensors are new, 1 is old...but the numbers of all 4 sensors are almost the same...


front right (old) 1 186
frond left (new) 1 198
rear right (new) 1 128
rear left (new) 1 172

[bloku]

Ok. I see, my firewall stoped the link.

If they works that seems that conttroler (under the back couch) has an electrical problem. What is happening after using difflock on and after off? ABS are working or crash down after few km?

[bobo23]

I have a small problem as u can see on picture.. Actuator havent the rod...BUt when i pull diff lock, it lights yellow, but ABS not shows on dashboard

[bloku]

In my opinion controller of ABS made some problem, probably no conections between sensors. If You have ON/OFF ABS switch on board try to check also.

The only solution which i see are on controller or switch.

[bobo23]

Switch is functional...when ABS lights ON i can reset (turns off) 2x pushes of abs switch...Maybe the gap between sensors are problem...but i havent osciloscope to check it and try to find one...

or how check abs switch?multimeter again?


Controller?U mean a ECU?

[bloku]

Switch You can check by multimeter - signal between connectors.

Not ECU (engine modul) . ABS has own controller - 857907379 made by bosch

[Jarewa]

You can also check the resistance of the sensors at the controller itself, maybe it is also the cables.