PNP Switch Malfunction
 

My Check engine light reads this: P1780 PNP Switch Malfunction
Does anyone know what this code means, or what I need to get fixed?

Ummm... I think you answered your own question of what the code means ;) Bring the car to the dealership to get it fixed up.

they told me it that the pnp switch was fine, and that it was alarm's wiring, which has been in place for over a year.

Not sure if this is any help, but PNP means positive-negative-positive (transistor). So when you have a "switch malfunction" with it, most likely it's an electrical failure somewhere in the system, perhaps in the theft-deterrent system like you said. Do you notice any electrical differences/changes when you drive or lock/unlock the car?

At any rate, I'm just breaking down the diagnostic error piece by piece, so hopefully that makes some sense. Now how to deal with the problem, you're pretty much on your own, but as I mentioned, it is best to bring the car to the dealership for a check-up on the check engine light. This is all the info I can give to ya ;)

I know this thread is old and dusty but I was wondering if anyone would know why an alarm system would trip that particular CEL... It happens in my Solara and my 2GS3 sometimes when I use the remote start. I installed prestige alarms on both.