seperate the TS harness. see if the white wire in the body half of the connector is hot with the brake pedal depressed. jump 12V to the 2 wires Nacho mentioned in the same body half of the connector & see of the brakes lights light up
Actually wouldn't need to disconect the plug, it can be made with plug conected and jump them out from back of conector with a small wire.
Once it happened to me the white wire on TS plug was broken down the wire cover, but TS itself was still good.
About the replacement TS available... several brands but to me all are made by the same manufacturer. They get all same wiring color codes ( way diff from the original ones ) and same yellow canceling cam. Is about luck, some came out from factory better than others. A friend of mine got one with couple of wires swapped out at turning switch riveted terminals. He had to cut and splice correctly those to make it work as it must ( or swap them out at plug ). It took us around 20 minutes to find the reason why it wasn't working good untill decide to track wire by wire from an original one and comparing with the replacement piece. Then also compare with other replacement TS pics on the web which confirmed that. A factory assembly mistake. Sure these chinesium pieces won't last long the same than originals NOS, but for the price of NOS one you can get 3 or 4 of the chinesium pieces, AND usually now our cars are not driven like before so they can hold the new use for a decent time. SO if you don't get the chance to get a NOS one, the chinesium replacements are still a "decent "option.
Used ones are a good option, BUT is also a random luck, unless you certainly now the use or abuse of those units... would be great to get them from a JY car with speedo still there and low mileage.
One way to certify the low use of used ones is the horn ring contact roller conditions. Is not weird the roller getting stuck and beginning to get flat out by the horn ring friction down the steering wheel.
Later Mopar replacements ( incorrectly being sold as NOS ) and chinesium replacements are not anymore with the roller stud, but a flat stud... still spring loaded thought.
ON A SIDE NOTE:
If the test shows/confirms a damaged TS A canceling cam replacement ( which is also available and cheaper ) could make the fix job! And wouldn't need to replace the full switch. The canceling cam section is which carries the brakes contacts same as turnings of course. So would worth the try.
