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Kit allows up to 15 amps from your RV's battery to be used to maintain the charge of your towed car's battery while the car is being towed. Charge line connects to the 6-way or 7-way plug on your vehicle. Requires separate charge line in RV.
Features:
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Speaker 1: Today on our 2008 Chevrolet Silverado, we're going to be showing you how to install the Roadmaster Battery Charge Line Kit for Towed Vehicles, part number is RM-156-25.Now this charge line kit is really important on these GM vehicles with the steering wheel lock situation, you have to leave your key on. Even though you turn off the fan, you turn off the air, you turn off the radio, it still drains the battery. This allows us to take power from our red wire that we've got connected to the 12 volt power source on the back of our RV, that goes through a breaker and we've got it connected right here to our positive battery cable.This gives us a trickle charge effect. As we're driving down the road, the battery's constantly getting a little bit of a charge and a little bit of a charge to keep it up and maintained. The breaker is in place to help prevent any kind of overloading. If you're vehicle, maybe you've left the radio on or you've left the fan blowing, it's going to be drawing power from your battery of course.That excess draw will cause this breaker to heat up slightly and disconnect power temporarily until that system cools back down and it'll make contact again, so it's a very safe and very effective way to charge your battery while you're flat towing.The first step in the installation is going to be to get our breaker mounted.
Now the gold stud is going to run to the positive battery source. The silver stud is going to run up to the plug on the front of the vehicle, so you want to mount that accordingly so you can route your wires the way you want to. We're going to be going behind this panel to make our connections, so I'm gonna mount my breaker pretty close, right in there should be okay. Get one of our holes started here. It's started, we'll put our breaker on and we'll put our second screw in the top there.Now we're going to grab one of the smaller ring terminals from our kit and also our red length of wire, we're going to strip the end of that back, I'm going to add that ring terminal right on there.
We're going to take off the nut that's on the silver stud, place the ring terminal in behind it and get it secured down.Now we'll start running our wire. We need this to go down towards the plug on the front of the vehicle. I like to use plenty of zip ties to keep everything secure and just kind of tuck my wire back and out of the way anywhere I can. As we route our wire up here to the front, we just need to avoid any pinch points or any sharp edges that might cause damage, also any significant heat sources, but other than that, you can really pick the route of your preference, and we can just bring that out the same hole our wiring goes through.I'm gonna trim our wires off here, start making the connections to the back of our plug. Now we're going to be using a six pole plug, part number BX88206.
As you can see, this is going to be a six pole plug, we need one for ground, one for running lights, one for left turn and brake, one for right turn and brake, so that's takes up four. To add a charge line, you'll need at least one more.To install it, we're just going to pull the boot off the back. I'm gonna get it slid on there first. We'll strip back each of our wires. I like to give 'em all a twist and then looking at the back of our plug, we're gonna start right over here, this is about 3 o'clock position.
That one's marked GD, that's gonna be our ground, which will be our white wire. You can see that little set screw. We're gonna loosen that up, place our wire in and then tighten that back down.Next one will be our yellow wire for our left turn signal. Then we've got out green wire for the right turn signal. Depending on your setup, your power will either come through the center port of the plug or through the outside port. In our case, it's gonna use the stop signal port, which will be the next one counterclockwise here, so that's where our charge line wire's gonna go. The last one on the outside which would be just clockwise from the ground wire we installed first, is gonna be our brown wire for the trailer marker, or the running lights on the trailer.Now we'll run a click test just to ensure that we've made the proper connections. We want to plug in our wiring from the RV and now in this case, our RV has to be started to provide 12 volt power, so it's gonna be a little bit loud with the engine running. But, once it's started, we can tested the breaker. If we have power at the breaker before we hook it up to the battery, we're getting proper signal coming through which will charge our battery ports.Now to test it out, we're going to need a test light. We just want the clamp to go to ground, there's a stud right there to use and then when you touch the stud, if you get a signal, you've done it right. We're getting the correct signal, we're ready now to connect that breaker to our battery.Now we're going to take the short length of wire that we have left and get both ends of that strip back. You're going to have two ring terminals left in your kit, one larger, one smaller, it doesn't matter which side those go on. Let's get one on each end of it. Now this side with the smaller ring terminal, goes to our breaker and that should go to the copper terminal.Now I'm going to use this connection point right here. I'm just going to pop that cover off, just pull straight out on it. So we've got a nice large stud right there. We're going to use a 13 millimeter socket to remove that. Get our ring terminal placed over top and then just put the nut back in place.Now we'll use a 10 millimeter socket, we're gonna tighten down both of our nuts on our breaker there. We can pop our cover back on there. That wire can come right out down with that big cable there. And that's really all there is to our install.With everything back in place, that's going to complete our installation of the Roadmaster Battery Charge Line Kit for Towed Vehicles, part number RM-156-25 on our 2008 Chevrolet Silverado.
Customer Satisfaction Score:
96% were satisfied with this product
4% of customers were not satisfied
Ratings & Reviews
Jeffrey
11/19/2022
I have no regrets with this purchase. Items preform as advertised with no issues. I am very satisfied with Roadmaster and Demco products.
Ken
2/27/2026
Great little product. Worked great while we needed it flat towing and the brake controller and lights were being activated. Now the Jeep is babied , trailered and enclosed.
Gwendolyn Y.
2/27/2026
Victoria H.
1/9/2025
That's awesome Ron! I will let them know you reached out.
Ron
12/20/2025
The Roadmaster accessories work great - the brake switch in the car is ideal for turning it on and off as required.
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Condition: Like New
Notes: May have damaged packaging or minor cosmetic blemishes.
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Roy
7/30/2018
Still very happy with our purchase. We’ve towed over 10k miles and have had zero issues with our tow setup. I’ve shared my experience with several other RVrs and recommended your company for their needs. Thank you,