Strange 2015 issue

Went out yesterday to start my 2015 and I had nothing. No clicking, no lights, nothing. The battery was about 5 years old so I'm thinking it just died. I purchased a new battery and installed it. As soon as I did, I heard the fan for the AC blowing. The key was not in the vehicle and the switch was off. I look inside and the P is lit on the dashboard indicating its in park. I start the truck move it backward and forward and shut it off--same issue--P lit still have power to climate controls. I start fiddling with relays and get back inside. Power to climate controls is off and P is no longer lit. I tried to duplicate the issue but couldn't. I have no idea what I did or even if I did anything. Does anyone know of a relay that could be sticking that would cause this type of issue?

 

Check for rodent damage

 

Sounds like the fan stayed on and drained the battery. Look at the fan controls like the resistor and speed switch and see if something is shorted out

@Dm93 or @Jimmyh might have a schematic

 

Diagram
https://www.tacomaworld.com/threads/a-c-not-turning-on-even-after-installing-new-parts.674286/#post-23704046

The control power side of the Heater Relay is only powered with the ignition ON.

The relay itself it actually controlled ON/OFF by the speed setting switch in the dash. The switch is the ground for the Heater Relay.

Once the Relay closes it sends power to from the 50A heater fuse through the relay and to the blower motor. The speed for the blower motor is controlled by the resistor on the ground side.

The “P” light on the dash gets powered with the ignition on and goes through the neutral safety switch.


I can’t post a diagram as my phone is being stupid at the moment. Hopefully Dm93 or Jimmy can jump in. If not I’ll see what I can do later. Until then hopefully the link up top will suffice.

 

I don't have time to post a diagram right now or look ant any diagrams in detail but the blower relay (HTR Relay) control side is powered by the IG1 No2 fuse which is only supposed to be hot with the key in the run position, I suspect you either have a problem with the ignition switch or there's an aftermarket remote start installed that's having issues.

 

I too would guess Ignition Switch or aftermarket remote start. Or a wiring issue. It might be very hard to troubleshoot unless you can reproduce the problem. If it is a problem it will surely come back in time.

I would be careful and make sure everything is off before leaving the truck for a while.

 

I agree. Set the blower switch to Off as well as the head lights.
Those will drain a battery pretty quick.