My pos Strat copy suffered from this, and it was a disconnected wire in the jack socket, which was an easy fix. You can check the socket and see if the wiring is sound or not.
If you’re semi-confident, you can unscrew the 4 screws on the panel and see the state of the wiring under. As far as I can tell, you’ll have two sets of wires from this module. One will be from the module to the jack socket, and the other set of wires will go to the pickup (which should be under the bridge). Normally the wiring to the pickup will be a thinner shielded wire. If I had to bet a small amount of money, I would say that the wiring to the socket is where the problem lies. If it’s not any of those things, then there will have to be a problem in the pre amp circuit