7 pin trailer connector

[RTRAM]

I have a 93 CTD and want to upgrade from a flat four to a 7 pin. I put the flat 4 in just after I got the truck and it works fine for the little trailer, but I want to start hauling a car trailer and need the trailer brakes. The truck brakes are good, but the trailer tends to steer the truck when I slam on the brakes at freeway speeds.



So, how do I hook into the electrical system, what gauge wire should I use, do I need fuses in the circuits, etc.



Do I need a brake controller, or anything else?



Also, I was hauling a trailer with a full size Blazer. I figure the trailer weight at about 6,000 pounds. What is the capacity of the CTD for gross vehicle weight? The CTD pulled it like a bid dog and even stopped fairly well.

 

[sdstriper]

Wow. I'll say you should get a trailer brake controller ASAP too...



Hoppy brand makes a plug and play trailer wiring kit, you choose the plug receptical thingy. Try Wally world, might not have one for our old stuff but it's worth a shot. Otherwise someone will have that kit. And it's worth it to not have to do all the wiring, you just unplug at the taillight connectors up under the back of the box and plug right into the factory harness. For a trailer brake controller I would put automatic reset circuit braker in and relay the trailer lighting. Hopefully someone can expand on that...

 

[KOG]

10ga wire for the brake controller straight from the battery. Use a 30 amp breaker in the line very close to battery. For the 12V charging line to the plug do the same. And run a separate 1-ga ground straight from the battery as well. You can get away with running trailer lights from the existing wiring only if the trailer has minimal lights or LEDS. For a big trailer with several clearance lights and multiple taillights you'll need to add relays with the power coming from another 10-12 ga wire right from the battery. The stock light switch in the truck is marginal in capacity even for running the stock lights so just adding clearance lights to the cab and tail gate can be more than it will carry for long unless you go LED for those as well. And if you tow a trailer over 80" wide clearance lights are a legal requirement for both the truck and trailer.

 

[DonSimpson]

you could try dodgeram.org, it's a web page from Dave Fritz thast contains some good information on dodge trucks, I have found it helpful in the past on wiring diagrams and tech tips. Just thought I'd throw in two cents worth.

 

[HBarlow]

If you are not a good backyard mechanic/electrician yourself you could find an RV dealer service department or local work trailer shop with an older tech who has been around for a long time.

An old timer would know how to wire an older truck with no factory wiring harness. Back in the '50s, '60s, and '70s cars and light trucks pulled smaller, lighter RV trailers all the time. In those days the RV dealer's service department wired up the harness with trailer brake controller and charge line from scratch. Youngsters at most RV dealers wouldn't have a clue how to do it now.