Audi CQ20V ABS problem

[Tom_]

Something prtttt do before the engine start but its a quick...But that sound what u have, mine dont do that....I ve ordered one used ABS pump, so maybe when i have it, i give it to test like you. Can be tested only with pump? I see that you have whole system

[M2ki]

Do you have battery voltage between pin 87 on big relay and pump chassis?
Yes, just connect charger or battery to the pump and short said 30 and 87.

It is the old system from my B3Q. Mine only worked for a few hundred meters, as it does not have any diagnostic capapility I built a new system from 1997 B5Q to find out which wheel sensor was faulty.
But the new system works fine with all the same sensors and abs rings. Will never know what was wrong with the old system

[Tom_]

Chassis u mean an abs pump body? Or ground or - on battery? Well done really cool idea

[M2ki]

Yes, abs pump body.

You can also connect to positive to this point, it is connected to terminal 30, then there is no need to bridge the pins, the pump motors starts right away.

[Tom_]

No nothing between 87 pin and abs body. Is need to have ignition key?

[M2ki]

No ignition needed. Pin 87 must be connected straight to battery.
Try between pin 87 and known good ground, engine or battery negative.

[Tom_]

negative on battery and 87 pin = nothing :/

[M2ki]

Then your positive is missing. It is a thick red wire, goes to fusebox L30 terminal, and from there straight to battery.
Maybe it is disconnected from the fusebox?

L30 terminals. Unfused. Straight to battery positive.

[Tom_]

That picture is from fusebox under the hood? Because now i am little bit lost

[M2ki]

Yes. Its the underside. This side can be accessed from under the dashboard.

[Tom_]

It looks little bit complicated but i never do anything with that, so i guess its not possible to have disconnected...

[M2ki]

Is the ABS ever worked, while you have owned the car?
Remove the cover above the knees and check if there are any loose thick red cables.
If there is no power at the abs pump, then there is two options, broken cable or loose cable. As it is pretty thick cable, it is unlikely that it is broken.

[Tom_]

ABS worked until i do renovation of subframes ...So everything new (brake lines, hoses, calipers, sensors) and other stuff. Ok i will check it

M2ki So i checked, there is ****** acces, but those cables are there...There u can see



edit : Now i have 12,7 voltage between battery negative and 87pin...But the ABS not give any sound with bridge pins

[M2ki]

Then your pump motor is broken. You could try briding pin 87 and that red wire which goes to the pump motor just to be sure.
Also to be sure measure voltage between pin 87 and pump chassis/ground wire. I saw some older pic where you installed new yellow ground wire, but check it anyway.

[Tom_]

Ok i check it today...i let you know. Ground wire on the pump or on the chassis (holder) ? And that red wire? ok i look at it. Thanks