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I am considering switching from drum to disc brakes on my 1999 LONG tandem axel boat trailer. It has brakes only on the front axel. I plan on replacing all the brake lines as well. I know I have to replace the master cylinder with a different style one if I switch to disc brakes. My question is-what is the wire that comes out of the disc brake master cylin-der? It goes to the wiring harness on the truck. What does it do?? Also, what kind of wiring changes do I have to make to my vehicle for this wire? Chris Rudy, Philadelphia, PA
Answered on: 9/2005
GEORGE: Your tow vehicle probably has a 7- prong electrical connection. Drum brakes on a trailer will have 4 prongs and disc will have 5 prongs. The wire coming out of the cylinder allows you to back up with the brakes released. MIKE: The wire coming out of an actuator for disc brakes if for a reverse lockout solenoid. Unlike drum brakes, disc brakes generate full braking power in reverse. The reverse lockout solenoid engages when your reverse lights are activated. The wire should be connected in line with your reverse lights.
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