How do I Bypass the OEM Brake Controller in My 2015 Silverado 3500 to Use Curt Spectrum?
Updated 07/23/2025 | Published 06/25/2025
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Question:
I am planning to install Curt Spectrum Brake Controller w/ Custom Harness on a 2015 Chevy Silverado 3500 with a factory brake controller. I understand the instillation, but how do I bypass the factory brake controller to disable it completely? I am installing this brake controller to fix the error message I keep getting Check Trailer Brakesinch and loss of trailer brake function. Then I get Trailer Connectedinch and function resumes without manipulating the 7 pin plug.
asked by: Andy
Expert Reply:
Hello Andy,
To bypass the factory brake controller so you can use the Curt Spectrum Brake Controller w/ Custom Harness - Dash Mounted Knob - Up to 4 Axles - Proportional # C36QV, you’ll want to start by removing the blue wire from the end of the brake controller harness that plugs into the truck. Once that wire is free, connect it to a length of 10-gauge wire, we recommend part # 10-1-1, which is sold by the foot. For example, if you need 20 feet, just enter “20” as the quantity when ordering.
Next, you’ll route that wire through the firewall, then run it under the truck and back to the 7-way trailer connector. Be sure to avoid any hot areas like the exhaust or moving parts like the suspension for safety and durability.
When you get to the trailer connector, look at the back of it (where all the wires hook up) and locate the pin at the 7 o’clock position (this is the trailer brake output). Carefully remove the wire currently in that spot, tape it off, and tuck it out of the way. Then, connect the new wire you just ran from the brake controller to that same 7 o’clock terminal.
A little extra work for the install, but will get things working as they should. What kind of trailer are you pulling? Is it something with Electric over Hydraulic (EOH) brakes?
Product Page this Question was Asked From
Curt Spectrum Brake Controller w/ Custom Harness - Dash Mounted Knob - Up to 4 Axles - Proportional
- Trailer Brake Controller
- Proportional Controller
- Electric
- Plug-In
- Dash-Mounted Knob
- Behind-Dash
- Up to 4 Axles
- Indicator Lights
- Multiple Trailers
- CURT
more information >
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on Trailer Brake Controller
Andy
7/8/2025
Thank you for the response. I ended up looking it up on AllData and I was able to add a pin to the existing chassis connector and running that to the back of the truck to avoid having to run the wire through the firewall. I am towing a trailer with traditional electric drum trailer brakes.