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Two Ways to Install a Trailer Brake Controller on a 2008 Dodge Ram 1500 with Factory 4-Way Wiring


I bought a 2008 Dodge Ram 1500. One of the Standard features is it has trailer wiring harness wired in with a 4 pin plug to tow trailers with the same plug in. I saw on your web site and 4 pin to 7 pin and 4 pin adapter which plugs into the existing 4 pin plug in the back of the truck. I got an email about what was needed for my truck but that isnt what need because that would a waste of money when I have already prewired set up for 4 pin. I also need to hook up my Prodigy P2 product number 90885 brake controller to the truck is the wiring from the back of the controller to be hard wired into the truck wiring and to the battery. The above mentioned adapter Part number C57674 has extra wires to do just that. Do you sell just the harness or do I have to buy a new controller. My previous vehicle that I bought in 2009 had the controller on it. The adapter plug for the controller stayed with vehicle when I trade it in. Can you help me or not? Dont send me information for a complete wiring from front the back like I already had in the previous email. I know that is all it shows but I think that the above adapter will work.


Expert Reply:

There are 2 ways you can install a brake controller. On a 2008 Dodge Ram with a factory 4-Way, we usually recommend a hardwire installation using a 4 and 7-Way installation kit # ETBC7. It includes an adapter that is just like # C57674 but it also comes with everything else you will need to complete the installation of your P2, # 90885. However, there is an alternate method which I will also explain after the ETBC7 explanation.

The 4-Way on your truck has the lighting functions for a trailer only and does not have the wiring run back for the electric brakes, 12 volt power, or reverse lights. That is why you have to hardwire in the ETBC7. The wiring for a brake controller may also not be present so it has to be hardwired in as well. The ETBC7 provides everything you will need.

If the trailer does not need a 12 volt feed or reverse lights then you will not have to wire those in. You will still need to run a wire from the brake controller blue wire all the way back to the adapter blue wire for output to the trailer brakes. The white wire on the adapter must be grounded to the truck frame.

I have included some links that explain the ETBC7 installation for you.

The second method is a little different. It is possible that your Ram has a factory port in which you can plug in an adapter to go from the controller to the truck. The harness is # 3020-P. I have linked a video showing where it would install (underneath the dash, to the left of the steering column, taped to another harness near the emergency brake pedal).

However since the truck has a 4-Way and not a 7-Way, the factory side may not be fully functional so there are some additional steps to take to complete installation. First consult the owners manual for the fuse location for power to a brake controller to insert the proper sized fuse. If the controller powers on then you know it is connected from the power distribution box to the factory brake controller port. If not, then you will need to hardwire the controller after all.

For the brake output wire, it terminates near the front wheel well in a connector. Usually located under the driver's side of the vehicle, right behind the front wheel well is a wire connector. There are more wires on the hood side (right side) of the connector than the hitch side. Using a circuit tester like # PTW2993 you can locate the wire that supplies power to the trailer brakes. Usually, it is the blue wire.

You will need to tap into this wire using wire # 10-1-1, sold in 1-foot increments, and run it all the way back to the adapter, like # C57674 blue wire. Enough wire will be needed to make it from the front wheel well to the end of the truck bed. After mounting the new trailer adapter and plugging it into the original 4-pole connector, installation is complete. Do not forget to ground the white wire to the frame.

Often times the connector in the wheel well area is difficult to get to and since you need to route wires anyway we normally recommend a complete hardwire installation. I have included some additional links to help with this second method of installation.

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