Trailering Back up Light Question for KJ Mechanic

[AtlanticBlue04KJ]

I use the KJ to pull a boat. The boat has surge brakes that energize when I stop so they also slide and energize when I go in reverse. Some trucks have a fifth wire to energize a solenoid that bypasses the trailer brakes when you go in reverse to back the boat up. The KJ just has a regular 4 wire flat plug. The boat has 5 wires - the fifth wire used toi energize the bypass solenoid when backing up.... I would like to use a signal from the back up lights to energize the solenoid and release the trailer brakes when backing up. I have looked at a wiring diagram and the KJ uses a transmission switch to energize the back up lights. I did not see a fuse anywhere between the transmission switch and the lights. I am worried that the boat trailer solenoid might create enough current to hurt the transmission switch that energizes the back up lights...What is this switch like? Is it like a little micro switch or is it OK/ Are the contacts big enough to handle more than the lights themselves? Any hints or suggestions appreciated. Thanks.

 

[kb0nly]

You could try this...

Tap off the backup light circuit and use that to drive the coil of a relay, then run a fused lead from the battery to your relay and the output of the relay back to your trailer plug to drive the solenoid.. Problem solved for about $10.

 

[JeepJeepster]

Yeah, I would definitely use a relay.

 

[kb0nly]

Looking at it all in the service manual i would say a relay is the best way to go. I doubt you could pull enough current from the switch. Your best off tapping off the backup light wire in the back right corner, the main rear end harness where the trailer wiring also connects in.

If you wanted to cheat a bit... Tap off the backup light wire at that harness and run that to the coil of the relay, there is a body ground bolt there too for the relay coil ground, then tap off the rear power outlet to feed the relay instead of running a wire back from the battery. Then you can also neatly run that fifth wire down through the floor grommet with your four wire trailer harness and install the five plug receptacle.

 

[AtlanticBlue04KJ]

Thanks For The Help

Think I will do the relay thing...Good points. I appreciate you taking the time to help me.

I have had a lot of vehicles....Four Jeeps - Wranglers, Grand Cherokees and Broncos and pickups this and that ---

BUT I really like this little blue Liberty a lot....It does anything I ask it to. It has exceeded my expectations.

 

[kb0nly]

Think I will do the relay thing...Good points. I appreciate you taking the time to help me.

I have had a lot of vehicles....Four Jeeps - Wranglers, Grand Cherokees and Broncos and pickups this and that ---

BUT I really like this little blue Liberty a lot....It does anything I ask it to. It has exceeded my expectations.

Blue is a great color... Hmm, perhaps i'm a bit prejudiced.... LOL