No Power at 12 Volt Pin In 7-Way on a 2008 Toyota Tundra

Question

Question:

I have a 2008 Toyota Tundra six cylinder and I’m trying to wire my trailer brakes. The issue I have is, there is no power on the black wire in the factory installed plug that the harness plugs into. Any help with this is great appreciated.

asked by: Roger

0

Expert Reply:

The first step I would take would be to check the 30-amp trailer brake controller fuse which is located in the # 10 slot on the fuse box under the hood of your 2008 Toyota Tundra. If the fuse is still intact, then you will want to move to the 7-way trailer connector. Using a circuit tester like part # PTW2993, check the black wire on the back of the 7-way way while the vehicle is running. If you are getting power here then the problem is in the trailer connector, and it will need to be replaced with something like part # HM11143395. If you are not getting power in this location, then you will need to begin tracing the black wire back as far as you can while checking or breaks or frays. If you still do not see anything then the sort may be located in a part of the harness that is inaccessible therefore, I recommend running a new wire to the battery with part # 10-1-1 and part # 9510.

expert reply by: Conner L

0

Paul M.

7/24/2020

I also have a 2008 Tundra with the 6 cylinder. I too have no power to the controller or in the factory wiring harness. Fuse 10 under the hood (TOW BRK 30A) is good. Fuses inside (#47 ECU-IG NO.1 7.5A for anti-lock brake, stability control, trailer towing and #53 Tail 15A for tail lights and trailer lights) are good. There is a cartridge fuse slot under the hood marked SUB BATT 40A for "trailer towing" that didn't come with a fuse. However, there is only one blade in the slot. That blade has power. Did Toyota purposely remove the connection from the fuse box even though the wire is in the wiring harness? I'm thinking I will have to run a new separate power line.

Reply

Chris R.

7/29/2020

Is there a way to get a new fuse from a dealer or local auto parts store for that spot? That location would definitely be what's tied to this circuit.

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Paul M.

7/29/2020

@ChrisR The hot connection is there but the other tab that the fuse should plug into is not. I suppose the main wire for the controller is somewhere in the harness which goes into the fuse box but it was never hooked up.

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Jon G.

8/6/2020

@PaulM It looks like you found your problem. In this case you'll probably want to do what Conner suggested and use a length of 10 Gauge Wire # 10-1-1 and route that from the battery (through the Circuit Breaker # 9510) back to your 7-Way connector. Here is a link to an article about routing the power wire for you to check out.

Helpful Links

faq-routing-a-power-wire.aspx

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See All (10) Replies to Paul M. ∨

Answer 1

The wiring harness you should be using on your 2013 Toyota Tundra is #3040-P. While it is unlikely it is wired incorrectly it is possible. You can use your test light to test the connector on the vehicle (where 3040-P plugs into) and see if it has…

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Answer 2

I recommend using 40 Ft 5-Way Trailer Wiring Harness #A40W5B, which is a kit that will replace your entire 5 way boat wiring setup and give you the 5 way connection at the front of the trailer. The lighting wires are 40 feet long, which will be…

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Answer 3

The easiest way to troubleshoot your trailer lighting functions is when it is not connected to the tow vehicle. Apply 12V power from the truck's battery or a well-charged spare if you have in the garage directly to the contacts on the trailer…

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Answer 4

My suspicion is that you have a poor ground connection somewhere on your trailer. The fact that everything works fine until the running lights are turned on is the dead giveaway. When the tail lights are turned on, the trailer lighting is drawing…

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Answer 5

Most often the root cause for issues with trailer lighting is a weak ground. Strange as it may sound, a loose or rusty/corroded ground can cause a vehicle's trailer wiring harness to badly misbehave and shut down some functions. It may also just…

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Answer 6

You should have continuity between the 5 o'clock brake output pin and 7 o'clock ground pin in your 7-way connector with the brakes applied. I recommend turning the trailer brake controller to its max setting and having someone apply the…

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Answer 7

Is this occurring with just ONE of several trailers, or with all of them? If it's just one of them- it sounds as if you've pretty much narrowed down the problem to the running lamp circuit on that one trailer. Somewhere in the wiring…

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Answer 8

For your electric jack, there are only three possible explanations for your jack not working with a charged battery. Either power is not getting to your motor, your motor is bad, or your ground connection isn't working properly. To test power,…

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Answer 9

I would be happy to help. The Tekonsha P3 brake controller you referenced would be an excellent choice for you. The P3 is extremely easy to use, and has controls that are intuitive and simple to understand. The diagnostic feature is unique in that…

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Answer 10

The best trailer brake controller option we have for a 2022 Toyota Tundra is the Curt Echo Mobile Trailer Brake Controller part #C51180. This controller will simply plug into the trailer connector so there is no drilling into the dash or taking up…

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Answer 11

You will want to get under the hood of your 2020 Toyota Tundra and find the 30A TOW TAIL Trailer side light fuse in the #9 position. This is what will control the power going to your 7-way way harness. This fuse is either missing, blown, or there is…

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Answer 12

In order to use a third brake light for both brake and running light signals, you would need to use a light with turn, brake, and running light capabilities such as the Thinline LED Trailer Tail Light part #STL59RB. As most trailers are a 3 wire…

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No Power at 12 Volt Pin In 7-Way on a 2008 Toyota Tundra

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