brake warning light on 2003 Volkswagen Passat

getting brake warning light coming on pads are fine so is brake fluid and sensors seem ok what cud problem be

Asked by for the 2003 Volkswagen Passat
Looking at a wiring diagram for your car it appears to have a separate warning lights for the brake fluid level and park brake problems. If the brake fluid sensor has failed try disconnecting the sensor at the resivior. With the engine running, does the light stay on? Bridge the connector with a paper clip does the light go out? The brake pad sensors have two wires going out to each brake pad the wires must have continuity across these wires (signifying the brake pads thickness is OK) to keep the b/pad light out. If you haven't got an OHM meter disconnect the sensor harness one by one and bridge the sensor harness with a paper clip to locate which sensor may have failed. After these basic checks you are going to need a wiring diagram to determine where the fault is. If you can gain access to the park brake switch disconnect it and see if the light goes out with the engine running.
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If you have access to a scan tool check for fault codes in the ABS.
You may well retrieve codes relating to "no communication with instrument cluster". This is very commonly due to problems in the ABS control module. Additionally the scan tool may not communicate with other vehicle systems unless you unplug the ABS module , or won't communicate with ABS at all. In either case the ABS control module is probably defective. A new or rebuilt ABS module is called for.
This is a very common failure.