87ChevyV20
Full Access Member
- Joined
- Oct 16, 2022
- Posts
- 90
- Reaction score
- 46
- Location
- Maine
- First Name
- Jason
- Truck Year
- 87
- Truck Model
- V20
- Engine Size
- 350
I really like how new trucks have separate wiring for the trailer. If you blow a fuse on the trailer, it doesn't knock out the truck lights too. And in my opinion, the factory wiring wasn't designed to handle splicing in trailer wiring at the back of the truck.
I had the idea to use a fuse/relay box to add the trailer wiring. So I bought a few things and finally finished it up the other night.
Item List
6 Slot Fuse/Relay Box
Proper Trailer Cable
Bus Bars
Fuse Tap
Big Fuse Holder
Cole Hersee Continuous Duty Solenoid
8 Gauge Wire
Brake Controller
Brake Controller Pigtail
There is other wire and odds and ends that I had already that I won't include here.
First thing I did was mount the bus bars on the driver side fender in the engine bay and mounted the Cole Hersee solenoid on the drivers side core support near the bus bars.
I ran the 8 gauge primary wire from the battery to the bus bars with the big fuse holder close to the battery and the solenoid close to the positive bus bar.
To trigger the solenoid, I grounded it from the negative bus bar and I used a fuse tap in the cab on a key on power source to kick the solenoid on only when the key is on.
I bolted the fuse/relay holder to the inner fender on the drivers side.
There isn't nearly enough room to put things like this in the engine bay as I would like.
I used all 6 spots in the relay box and these are all key on power.
1-12 volt
2-Back up lights
3-Tail lights
4-Left Turn/Brake
5-Right Turn/Brake
6-Brake controller
I wired in the signal wires for 4 relays to the corresponding circuits(back up, tail and turn signals) to the existing wiring going to the back of the truck as this doesn't add much extra load to the factory wiring.
The 12 volt and brake controller are just on when the the key is on.
I ran the trailer cable to the back of the truck.
A note about the trailer cable I got. There is a bunch of other trailer cable out there, but most of them have all 12 or 14 gauge wires in it.
The one I bought has 2-10 gauge, 1-12 gauge and the rest are 14 gauge. Just something to watch out for.
The trailer plug I had was a factory GM bracket and plug off a mid 2000's 5500, I think.
I also had the quick release plug for the back of it. I went a little above and beyond here as I wanted the least amount of splices in the system.
The quick release plug I had used Metri-pack terminals. It took me quite a bit of time to source the correct terminals because I didn't know what I was looking for at first.
6 of the terminals are 280 series and one terminal is 630 series. After getting all the necessary seals and terminals, I terminated the plug cleanly and professionally. There are no butt connectors on this cable at all.
The other end of the trailer cable, I removed the sheathe off the front 6 feet of cable to ensure I could terminate the ends cleanly like on the back. I also terminated the brake controller pigtail like I did the trailer plug too.
All the wires run pretty much uninterrupted and terminated in their respective spot.
I still need to print a sticker for the top of the relay box to remind me which circuits are which.
I am very happy with this setup and hopefully it serves me a long time because I don't want to have to do it again!
I had the idea to use a fuse/relay box to add the trailer wiring. So I bought a few things and finally finished it up the other night.
Item List
6 Slot Fuse/Relay Box
Proper Trailer Cable
Bus Bars
Fuse Tap
Big Fuse Holder
Cole Hersee Continuous Duty Solenoid
8 Gauge Wire
Brake Controller
Brake Controller Pigtail
There is other wire and odds and ends that I had already that I won't include here.
First thing I did was mount the bus bars on the driver side fender in the engine bay and mounted the Cole Hersee solenoid on the drivers side core support near the bus bars.
I ran the 8 gauge primary wire from the battery to the bus bars with the big fuse holder close to the battery and the solenoid close to the positive bus bar.
To trigger the solenoid, I grounded it from the negative bus bar and I used a fuse tap in the cab on a key on power source to kick the solenoid on only when the key is on.
I bolted the fuse/relay holder to the inner fender on the drivers side.
There isn't nearly enough room to put things like this in the engine bay as I would like.
I used all 6 spots in the relay box and these are all key on power.
1-12 volt
2-Back up lights
3-Tail lights
4-Left Turn/Brake
5-Right Turn/Brake
6-Brake controller
I wired in the signal wires for 4 relays to the corresponding circuits(back up, tail and turn signals) to the existing wiring going to the back of the truck as this doesn't add much extra load to the factory wiring.
The 12 volt and brake controller are just on when the the key is on.
I ran the trailer cable to the back of the truck.
A note about the trailer cable I got. There is a bunch of other trailer cable out there, but most of them have all 12 or 14 gauge wires in it.
The one I bought has 2-10 gauge, 1-12 gauge and the rest are 14 gauge. Just something to watch out for.
The trailer plug I had was a factory GM bracket and plug off a mid 2000's 5500, I think.
I also had the quick release plug for the back of it. I went a little above and beyond here as I wanted the least amount of splices in the system.
The quick release plug I had used Metri-pack terminals. It took me quite a bit of time to source the correct terminals because I didn't know what I was looking for at first.
6 of the terminals are 280 series and one terminal is 630 series. After getting all the necessary seals and terminals, I terminated the plug cleanly and professionally. There are no butt connectors on this cable at all.
The other end of the trailer cable, I removed the sheathe off the front 6 feet of cable to ensure I could terminate the ends cleanly like on the back. I also terminated the brake controller pigtail like I did the trailer plug too.
All the wires run pretty much uninterrupted and terminated in their respective spot.
I still need to print a sticker for the top of the relay box to remind me which circuits are which.
I am very happy with this setup and hopefully it serves me a long time because I don't want to have to do it again!
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