audi 100 5cy brakes

My Audi 100 is suffering from brake problems after a few miles the brakes begin to bind. I did all the usual stuff ckeaing the calioers, cylinders etc
but still the same. In a moment of frustration I hit the top of the Dash and the brakes released only to bind again when I next used the brakes. the ABS light is in continuusly .
Is there anything under the dash that could cause this problem if so what do I do about it
Ian
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T44 I assume.
ABS light: check the fuse in the top of the ABS relay in Aux Relay panel under dash by your left knee. The decorative cover needs to be removed to get at it and that is more of a job than it should be.
Brakes seizing: Very likely that your Master Cylinder needs replacing. Test the MC by taking a bottle of cold water with you and when it seizes open the hood and pour the water over the MC. If that releases the brakes you need a new MC.
They go bad from excessive heat due to their location directly behind the radiator fan.
Tony '91 100q 5spd 4th T44 > BTDT
ian wrote:

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Thanks I got too the relay panel without too much trouble and yes a fuse had gone on the abs relay.
Next is to see if there is any difference in the driving which I doubt since the hot master cylinder problem seem very likely. This car is an electrical nightmare.the interior lights don't work the passenger seat wont move...... One other strange thing is the high beam light being on with dipped lights and off with High lights.... that can wait for another day.
Thanks for the help

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ian wrote:

You are probably right on that.
This car is an electrical

To catch a lot of electrical gremlins on the T44s check and fix wires in two places: - Wire bundle in the rubber accordion thingy in the drivers door hinge area. This is a source of many problems. The wires don't stand up to flexing. Broken and frayed wires. Check and fix them all with solder. It is also a good idea to allow more length to reduce binding and to use Marine wire as is has more strands for a given wire gage and withstands flexing better. - Same sort of thing in the wire bundle as in enters the trunk hinge on the drivers side. This causes problems in back and in the dash in addition to blowing fuses.

Might be a switched wire from a previous owners failed attempt to fix something. It might be an indication of the multifunction switch going bad. This is the part behind the steering wheel with the levers. You don't even want to ask the dealer what they want for a new one. Luckily they are fairly common in the bone yards.
The problem is that audi designed the system so all the power to operate the headlights goes through the high / low beam switch on the column. They used a high quality switch but electrical contacts go bad over time. When the resistance increases so does the heat and they finally melt.
The way to avoid this is to convert the system to relays so the column switch only handles low power. Couple DPDT 40 amp relays and some 10 ga wire is all it takes. Just tape the new relays behind the drivers side headlight and take power from the 12 volt power source just behind the passenger side headlight.
This is one of the first things that I did with my current '91 100q so I wouldn't have to deal with the problems in the switch. The side benefit is that it also increases light output a bit as well.

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