Hella Wiring on stock horn plugs

I highly recommend (very highly!) powering your Hella horns from the accessory bolt on the positive clamp of the battery cable and using a relay to transfer the power to the Hella horns based on a trigger the relay receives from one of the existing horn wires. That will ensure that your Hella horns get full power, don't sound wimpy and that your Sienna's horn circuit is protected from overload. Yes, some people get away without using a relay - I tried that once and learned a lesson.

If you have the red Hella Supertone horns and plan to place them in from of the radiator, the red horn grills are easily removed and can be spray painted black so that they are not obvious. You can even leave your current horns in place and use them in conjunction with the Hellas.

Any auto parts store can set you up with a horn relay - it should come with a wiring diagram. The last time I did this I bought the relay, wire and connectors at an Advance Auto store and fabricated a wiring harness and covered it with heat shrink tubing - looked OEM when installed.

Without the relay, its a 30 minute DIY, tops. The supertones are a direct change on the existing horn. I used these quick connects from Advance Auto



Connections:

Stock Wire +VE (each horn) ---> One terminal on the Hella horn (each). Since the horn terminals are polarity free, you need to ensure that both connections are on the same side i.e. with horns mounted, if you pick the left connector on the 1st horn, then pick the same left connector on the 2nd one

The other connector on each horn connects to ground (-VE). I used the same bolts which were used to connect the horns.

Here you can see them from teh front and top






and with the Grill on...




If you want to use the relay (it comes with the supertones), use the connections below