What sort of trouble? Did you use a P3 harness specific to your truck or are you splicing into the factory harness? Factory tow package? Have you verified the function of each contact blade in the receptacle? Do those functions match the wiring of your trailer plug?

If factory, the Toyota tow vehicle receptacle should look like the left side of the figure below and the associated fuses for various functions are at the panel next to your battery.

This is how your truck receptacle was wired from the factory, you should ignore wire color and focus on function. Is your trailer wired the same way?

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Thanks for the reply katoomon. I think I know what happen to my controller. When I went to test the emergency brake on my trailer (that I just purchased last year) it blew one of the fuses under the dash and I think fried my P3.

After checking all the wiring on the trailer I found that the battery for the emergency brakes was wired up backwards! Waiting on the new P3 to show up to get everything working again. Now I have to try and get the dealer or manufacturer to own up to their mistake.

I would still like to know how the truck is wired. Looks like there are multiple fuses for towing and there should also be a relay for power.

 

I had a similar experience, the PO of the travel trailer I purchased had it wired as + ground, dope. I picked it up in a snow storm and did not take the time to verify any connections other than running, turn, and brake lights. It did no occur to me to disconnect the tt battery before hooking up to tow.

On my 2003, there was a 30 amp fuse under the hood for 12 VDC power to the trailer and no relay; the same is true for the 2016 SR5 I just picked up a months ago. Look under the fuse box cover for the position. You can confirm that the #4 blade is hot (key on) with a test light .


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