Convertible top wont go down? - 2003 Audi A4 Cabriolet

Check the tops hydraulic lift pump fluid level, if it is low check for leaks under the car in the rear.

try removing the negative battery terminal for about 10 minutes, and or check fuses, use a test light . 6 12V Circuit Tester with 5 ft Lead

Clean the battery cables this may be a corrosion problem, also test the battery and the charging system performance.

Where did you get micro switch?

Check in the trunk to see if the insert that the top sits on is snapped into place. If it is and the top still will not go down, unsnap it and resnap it. There is a sensor that detects if it is in place to prevent the top of the car from being damaged.

You are probably low on fluid.
Behind the rear seat is the motor/pump/reservoir.
With the top down, fill the reservoir with ATF.
Cycle the system a few times.
Repeat till the reservoir will accept no mor fluid.
Chedk the lines and cylinders for leaks. The fluid must be going someplace.
You can change it to a manual top by removing the bolt at the top of the cylinders and lowering the both shafts down into the cylinders.

This happenrd to me the first few times after filling the tank. When the roof stops push the switch to up then back until movement stops then go back to down, eventually it will get rid of all the air in the system and the roof should start to work.

i would check to see if the luggage compartment (trunk) isn't expanded. If it is the convertible top module wont allow the top to move. If the trunk is open or there is a problem in the wiring and a check control message is displayed the top won't open either

check up and down swich,maybe bad svich

Your top motor is in the trunk on the drivers side wall behind the panel. Remove the two screws to remove the cover. Check the fluid level in the reservor. Check that no lines have come off of the pump and have someone pushing the top down button while checking. If this is not the problem, then it is a possibility that the e-brake connection is not working right.