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Trailer Wiring Harness Installation - 2003 Dodge Ram Pickup

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How to Install a Trailer Wiring Harness on a 2003 Dodge Ram Pickup


Today on our 2003 Dodge Ram pickup, we'll be installing the Hopkins Endurance 5th Wheel/Gooseneck 90-degree wiring harness with 7-pole trailer connector, part number HM42137. To begin our install, we're going to start in the pickup bed. We're going to find a suitable mounting location for our 7-pole plug. Once we find our location, which we're going to go here in the pickup bed side wall behind the wheel well and in front of the rear stake pocket, then we can take our hole saw and drill out our 2 1/8" hole as per the instructions. Once we have the hole drilled out, we can move underneath the vehicle and feed our 7-pole connector up through the hole. Another option while you're already in the pickup bed, is to take the vehicle connection end or T-connector and feed it down.

Note, be careful when feeding it down around the sharp edges where we just cut out the hole. Now we have our 7-pole connector end remaining here in the pickup bed and before I install the 7-pole plug, we'll use some of the dielectric or terminal grease provided with the install kit to put on the end of the connector to help prevent corrosion that can build up from moisture over time. With our dielectric grease in place, we can go ahead and install our 7-pole connector onto the harness, pressing firmly together, making sure it locks in position. We'll then go ahead and mount the 7-pole plug here to our pickup bed. To mount it, we'll use the self-tapping screws provided with the install kit. With our 7-pole connector mounted here in the pickup bed, we can move underneath and continue routing our wiring and making our connections under the pickup bed.

Now we've moved underneath the pickup bed. We're going to go ahead and take the wiring harness, feed it up over the frame towards the center of the vehicle. The T-connector in our new Endurance harness will plug in-line with the manufacturer's wiring that plugs into the back of the bumper. To disconnect it from the back of the bumper, we'll first need to unlock the red locking tab by sliding it over, and these will get a little stiff over time. I'm just going to use a flat-bladed screwdriver to assist me in pushing it over. Then I'll press on the connector lock and remove it from the back of the bumper-mounted 7-pole connector.

Before we make the connection with our T-connector, we're going to go ahead and install some more dielectric grease on both ends, one on the vehicle side and one on our wiring harness side. Once we've finished installing the dielectric grease, we'll take the manufacturer's harness and plug in to our new T-connector. Push the 2 connectors until they lock in place and then slide the red locking tab back into position. We'll then take the other end of our T-connector and plug into the back of the 7-pole connector that's mounted into the bumper where we removed the manufacturer's harness from. Once it's locked into place, we'll slide the red locking tab over to lock it in position. We'll then take the remaining portion of our wiring harness and secure it behind the bumper.

To secure it, we're just going to use some zip ties to hold our wiring up and out of the way. With the wiring harness secured, you'll notice we left one wire out. This is a white wire with a pre-attached ring terminal that's going to get routed to the frame and provide ground for the 7-pole connector. To secure it the frame, we're going to use a self-tapping screw. With our wiring harness installed and secured, we'll cut off the excess from the zip ties to clean up our install look. With that, we've completed the install of our Hopkins Endurance 5th Wheel/Gooseneck 90-degree wiring harness with 7-pole trailer connector, part number HM42137, for our 2003 Dodge Ram. .


Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Joshua S
Video Edited:
Joshua S
Employee Chris R
Video Edited:
Chris R

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