Troubleshooting 2018 Toyota Tundra Brake Controller Not Recognizing Connected Trailer

Question

Question:

2018 Tundra brake controller does not recognize trailer connected. Please let me know how to simulate trailer is connected so I can check if the brake controller is producing voltage. Is there a certain resistance range expected from the trailer brakes, or from trailer lights? In my case the trailer brake circuit has 3 ohms resistance. The trailer light circuit has very low resistance as the lights are LED. Could that be the problem? Thanks,

asked by: Scott B

0

Expert Reply:

The brake light circuit actually differs from the brake controller circuit. If you check out the linked photo you can see that the brake/stop light circuit is actually tied to the left and right turn circuits as well which as in the 3 and 9 o'clock positions on your 7-Way. Your brake controller circuit should be in the 5 o'clock position on your 7-Way.

If your brake controller isn't recognizing that a trailer is connected then that means the pin in the 5 o'clock position isn't sensing a connection. For example, the Prodigy P3 # 90195 sends back a pulse with a very minimal amount of current to "test" if a trailer is connected. If there is no connection there or the circuit for your trailer brakes is damaged on your trailer end then that would result in the "no trailer connected" signal you are reading.

You can test to make sure that your brake controller is sending power back to that 5 o'clock pin by using your tester to see if voltage is present when you set the controller to max power and use the manual override. If you don't see power then there is a connection missing on your 2018 Toyota Tundra. If you are seeing voltage then the problem is on your trailer and you need to check the wire connected to the opposite pin on your trailer connector.

Make sure your trailer 7-Way is clean and free of debris and corrosion and then move on to the wiring. Check for places where the wiring is damaged or pinched and replace with 10 gauge wire # 10-1-1. This should fix your problem.

expert reply by: Jon G

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Luke S.

3/8/2024

Hey mate why would my Indicator be coming on when I put my foot on the brake?

Reply

Jon G.

3/10/2024

@LukeS Is your trailer indicator blinking like it would if your turn signal is on, or are you just saying that the turn signals on your trailer light up as well as your brake lights on your trailer? Or is all of this happening on your vehicle side of things?

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Luke S.

3/11/2024

@JonG Hey mate my indicators are going solid when my foot is on the brake only on the trailer but when I use my indactors as normal it works fine and even when I use tail lights they work normally what would cause that?

Reply

Jon G.

3/11/2024

@LukeS The vast majority of trailers have the stop and turn functions combined on the tail lights so that may be what's going on. If these functions are supposed to be separated out (as in, they used to work in this fashion) then it sounds like you might have a corroded connection or damaged wiring somewhere. Check all of your connections and connectors for anything that looks out of place or damaged and fix accordingly. It may also help to try connecting your vehicle to a different trailer and your trailer to a different vehicle just to help isolate which end of the towing setup is causing the issue.

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Answer 1

Depends on the size of the trailer tires, without knowing what you have and that your current rims are 5-1/2 inches wide you most likely have the tire size 205/75-15 which could do either a 5 inch or 6 inch wide rim. The #AM20447 that you…

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Answer 2

The problems you are having with the factory brake controller on your 2018 Toyota Tundra, as you mentioned, are not too uncommon. This is really the case with most factory brake controllers regardless of the truck make or model, as many customers…

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Answer 3

You are correct, you should only be getting output when the brake is applied, or the override switch is activated. It sounds like the controller might be bad, but to make sure, you should probably bench test it before tossing it. Use a circuit…

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Answer 4

It's my understanding that your 2020 Toyota 4Runner should have come with a connector already installed up and behind the emergency brake pedal. If all you found was a bundle of wires and then a connector in your glove box then you should be able…

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Answer 5

That issue is going to be fixed by unplugging the vehicle battery for a minute then plugging it back in. Your factory brake controller's error messages were connected to the dash display you have on the truck so since the controller is no longer…

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Answer 6

To cover the easiest things first, make sure that the brake controller output or gain is turned up. If the power is low then the voltage on the blue wire will be low. When testing for voltage make sure to use the manual override and not the brake…

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Answer 7

First, put the magnet ground wires nearby the magnets on the trailer frame. Running them far away makes it harder for the system to complete the circuit. You mentioned that power is getting to the magnets but how much power? TO determine that you can…

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Answer 8

There are a number of reasons why the brakes on your trailer may not be working. Lets start with the easiest things to check. First, check the vehicle and trailer connectors for corrosion. This can cause a short inside the connector and the brake…

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Answer 9

At this point (June '19) trailer brake controller makers like Redarc have not had time to get their hands on the 2019 Tundra SR for doing test installations but there is one trailer brake controller that I can assure you will work fine for you so…

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Answer 10

You'd have to have the 6 volts wired in series to double their voltage so that Power Inverter 1000 Watts with Three AC Receptacles #WC3720 can be connected to it. I attached a diagram that shows how to do this.

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Answer 11

We have exactly what you need to hook up the 4-Way connector on your Toyota Tundra to the 5-Way on your boat trailer. You are correct that the additional wire on a boat trailer's 5-Way is typically used for the reverse lockout solenoid on the…

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Answer 12

Since your 2016 Toyota Tundra already has the factory 7-Way and wiring installed, replacing your OEM brake controller with the Tekonsha Prodigy P3 #90195 will be a breeze. All you will need to do is choose where you would like to mount the bracket…

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