GordDavey
Senior Member
- Joined
- Jan 2, 2019
- Posts
- 218
- Reaction score
- 108
- Location
- Toronto, Ontario
- Ram Year
- 2015
- Engine
- Hemi 5.7
Hi All, I'm not an electrical guy although I am learning fast as I've done a bunch of work on my Ram 1500. But there are some things I do not know and need to understand better about wiring, such as guage, drop %, amp and length of wire to understand what is the correct stuff to use and where.
I have two things I'd like to add to my truck. #1 Rear Seat Heaters and #2 A dual USB quick charge outlet.
I'm trying to understand what size of wiring I need and what I can / should / shouldn't do so I don't melt wires or end up with a non working item... or start a fire. I have a ton of left over automotive wire from rebuilding my truck from salvage so I have all kinds of wire from extra body harnesses, engine harness etc I can use, or I can use wire from the auto store. As I understand it automotive wire is better and more capable than the plain old auto store wire (GPT).
#1 - Rear Seat Heaters. I purchased an aftermarket heater kit. 4 pads, 2 switches. It's the same kit many people buy with the relays and switches built in, each relay requires 10amps for the main wire and a 5amp for the switch wire.
I think I can do this one of two ways:
A) Run a 12ga wire from the battery to the rear of the center console and connect both main wires from the relay, then tap off a power outlet to power the switches. Would the 12ga be too big/small ? Does taping into an outlet for the relay end up meaning that I shouldn't put something with a large current draw in the outlet from then on?
B) Looking at the wiring diagram for the truck (bought from Tech Auth) the OEM rear seat heaters ran off the same fuse as the heated steering wheel. Could I just tap off the 16ga PK/YL wire in pin 7 of the yellow connector to supply the 20 amps to the seat heater pads and just run a new wire from the fuse box to power the heater switches? Is this a terrible idea? I'd much rather come out of the fuse box with current that only flows when in Acc/Run or Run Only than a direct connect to the battery. Less chance of battery drain I would think.
#2 - Switching the power outlet on the back of the center console to a dual USB which requires a 10amp circuit. The power outlet says it has a 20amp fuse and uses 18ga wire from the fuse box. I can see the wire steps down to 20ga (I believe) just when it makes it to the power outlet. Since I'm replacing the power outlet can I simply use the power and ground from the outlet for the 10amp USB device and swap the fuse in the fuse box from 20amp to a 10amp one? The wires that come with this thing must be 14ga or 12ga, and the wire at the power outlet is so small in comparison so that I truly wonder if this is a good idea or not. Advice on what I should do/wire size would be really helpful.
In doing research on wiring and trying to learn and seeing different wire type and gauge to amp and length charts, they often seem to contradict each other, and the wire gauge that FCA uses for things just doesn't make much sense when looking at the charts I've found. Like the power outlet saying its an 18ga 20amp from the fuse box, from what I read it should be a much larger gauge to support 20amps at the length I estimate the wire to be. Any help or URL's you guys have to help me understand how to choose the correct wire size for this sort of stuff would really be appreciated. I understand there are drop percentages involved and the only way I can see some of the wire gauge sizing match is if the drop percentage is quite large.
Thanks for any insight.
I have two things I'd like to add to my truck. #1 Rear Seat Heaters and #2 A dual USB quick charge outlet.
I'm trying to understand what size of wiring I need and what I can / should / shouldn't do so I don't melt wires or end up with a non working item... or start a fire. I have a ton of left over automotive wire from rebuilding my truck from salvage so I have all kinds of wire from extra body harnesses, engine harness etc I can use, or I can use wire from the auto store. As I understand it automotive wire is better and more capable than the plain old auto store wire (GPT).
#1 - Rear Seat Heaters. I purchased an aftermarket heater kit. 4 pads, 2 switches. It's the same kit many people buy with the relays and switches built in, each relay requires 10amps for the main wire and a 5amp for the switch wire.
I think I can do this one of two ways:
A) Run a 12ga wire from the battery to the rear of the center console and connect both main wires from the relay, then tap off a power outlet to power the switches. Would the 12ga be too big/small ? Does taping into an outlet for the relay end up meaning that I shouldn't put something with a large current draw in the outlet from then on?
B) Looking at the wiring diagram for the truck (bought from Tech Auth) the OEM rear seat heaters ran off the same fuse as the heated steering wheel. Could I just tap off the 16ga PK/YL wire in pin 7 of the yellow connector to supply the 20 amps to the seat heater pads and just run a new wire from the fuse box to power the heater switches? Is this a terrible idea? I'd much rather come out of the fuse box with current that only flows when in Acc/Run or Run Only than a direct connect to the battery. Less chance of battery drain I would think.
#2 - Switching the power outlet on the back of the center console to a dual USB which requires a 10amp circuit. The power outlet says it has a 20amp fuse and uses 18ga wire from the fuse box. I can see the wire steps down to 20ga (I believe) just when it makes it to the power outlet. Since I'm replacing the power outlet can I simply use the power and ground from the outlet for the 10amp USB device and swap the fuse in the fuse box from 20amp to a 10amp one? The wires that come with this thing must be 14ga or 12ga, and the wire at the power outlet is so small in comparison so that I truly wonder if this is a good idea or not. Advice on what I should do/wire size would be really helpful.
In doing research on wiring and trying to learn and seeing different wire type and gauge to amp and length charts, they often seem to contradict each other, and the wire gauge that FCA uses for things just doesn't make much sense when looking at the charts I've found. Like the power outlet saying its an 18ga 20amp from the fuse box, from what I read it should be a much larger gauge to support 20amps at the length I estimate the wire to be. Any help or URL's you guys have to help me understand how to choose the correct wire size for this sort of stuff would really be appreciated. I understand there are drop percentages involved and the only way I can see some of the wire gauge sizing match is if the drop percentage is quite large.
Thanks for any insight.