Switch

Hello all, this is my first post and I would like to apologize if has been re-posted. Before posting this I did do a search but I just couldn't find anything that'd help me. I currently installing a train horn, yes a train horn, I would appreciate if no one gave me a hard time about it. As this is my truck.

I'm almost done, I got majority of it done, but I've run into a problem. I wanna be able to use my factory horn, flick a toggle switch have the factory horn disabled and than have the train horn instead. Could anyone help me out? Also I have an light on this toggle switch, I would like to have the light on when the switch is on. Any help would be awesome!

 

you need a standard 5-pin automotive relay. Find the horn wire in your steering column or engine compartment. Cut it in half. The horn side of that wire connects to pin #87a on the relay. The switch side connects to pin #30. Then, pin #87 connects to the train horn as the trigger (NOT A SOURCE OF POWER, SWITCH/TRIGGER ONLY) Then pin #85 connects to vehicle chassis (ground) and pin #86 connects to the switch in the cab. Your switch should have 3 pins on it if its lights. One is labeled "common" which gets grounded (usually the bottom pin) The output of the switch (usually the middle) is what is connecting to pin #86 on your relay. Then the input of your switch (usually top pin) connects to a 12v accessory or constant power source (depending your wiring preference) This can be done through an add-a-circuit tapping into the fuse box.

If reading this was like reading Chinese to you, then I highly recommend you dont try this without the help of someone more experienced in 12v automotive electrical and know how to use a relay. Its very simple, but dangerous to just try it on your own. Hope this helps

See diagram below:
"Train Horn Pressure Switch" is your steering wheel horn button
"Horn 2" is your oem horn wire (before it splits into 2 separate horns)
"Horn 1" is your train horn
*IGNORE where is say "blue/yellow wire in fuse box" that does NOT apply to you!*

 

Perfect! No, shouldn't be a problem, I will head to the auto parts store when I leave work.

 

Just be sure to test everything before your make it too permanent. I have not tested this first hand, and do not have access to the FSM to see the schematics for the horn circuit to confirm this will work. This is assuming that Toyota didnt do any tricky wiring or some crazy complicated over-engineered circuit design. It should work flawlessly, but always test as you go a verify everything first. Also, make sure you know which pin is what on your switch you have. Note that I said "usually" when giving the wiring info for your lighted switch. Let me know if you have any more questions. Or if you need to know which wire is the horn wire, tell me year and model trim and I will look it up for you.

 

Will do, appreciate it. I will let you know how everything went.