Have you been touching any of the wiring or connections anywhere in the vehicle? Sometimes when we run into a drain on a battery, for example, it's best not to touch any wiring or connections until you can get an idea of what circuit the draw may be on. Because if it's just a loose pin in a connector you can accidentally fix the problem and not realize where it was. It happens all the time. After so many years of use, connections, connector pins, even fuses or relays can lose their contacts, because they are constantly heating up and cooling down day after day. So, I wonder if just messing around with any main bulk connectors you may have fixed the issue. This just happened to me a couple weeks ago and the vehicle has not acted up since then. So now it's a matter of waiting until a component fails completely to replace it unfortunately.
As for the nozzles spraying different amounts, they are probably clogged up somewhat from not being used. The sprayer fluid contains alcohol to help prevent it from freezing in the winter, so if you can take the sprayer ends off and try to clean them out, you will get better results with at least the amount they are spraying.
The Body Control module (BCM) is what actually controls the sprayer motors. The multifunction switch sends a signal to the BCM, and it controls the ground side of the sprayer motors. The BCM is basically a computer module like all the rest, it needs a good power source, good ground, and good inputs and output circuits to work correctly. And diagnosing modules can be very difficult sometimes. It can appear to be a bad module when in fact it's just not receiving good input, output, etc. It's also on the vehicles data network, and that's a whole new few pages of typing to explain all that goes on during network communications.
So, for now, I would try to clean out the sprayer nozzles, and if you touched any connections or fuses that you remember, check them out again. Look for discolored fuses or connections that may have gotten hot. A poor connection is resistance in a circuit, and resistance results in heat.
Is that the correct mileage for this vehicle? 68,000? Thats surprisingly low. If the vehicle has sat for a long time, another thing to keep an eye out for is rodent damage. Mouse nests and things like that. Rodents love to chew on wiring, I have taken more rodents nests out of vehicles than I want to admit. They can do a lot of damage and they always will chew multiple wires, especially on vehicles that have sat for a long time. Sorry for the long post.
https://www.2carpros.com/articles/how-to-check-a-car-fuse
https://www.2carpros.com/articles/how-a-car-electrical-system-works
Friday, February 10th, 2023 AT 1:31 PM