Hopkins 4 pin tester

[nicholasgoodman]

I’ve been having problems wiring my tilt Jon boat trailer. I finally learned I needed to run the ground to the actual frame and not the front. That got me nice bright turn signals and break lights but no running lights or license plate light. I had bought the Hopkins 4 pin tester a few days ago to see if the problem was on my truck side. When I first tested it, all three of the lights came on like they should. But after today, I tested again and only the two indicators for the turn signals come on. No tail light indicator comes on now. What could be the issue?

 

[nicholasgoodman]

 

[nicholasgoodman]

Sorry for the bad photo quality, but as you can see this is the tester with the turn signals on, but not the tail, I did have my truck lights on also.

 

[KD4UPL]

I'd start with the fuse for trailer lights in the truck.

 

[nicholasgoodman]

I tested it, it’s good. Any other suggestions?

 

[dingbat]

Guessing since you moved the ground from the "front" to the frame, the "front" no longer is grounded

 

[nicholasgoodman]

Guessing since you moved the ground from the "front" to the frame, the "front" no longer is grounded

I moved the ground from the tongue near the hitch, to the main frame. I was losing connection at the pivot point and couldn’t get a good ground up front. I spliced in more ground wire ran it to the front of the main frame and got good turn and break lights.

 

[guy48065]

Now that your frame is properly grounded all the way to the plug, If your trailer light assemblies are grounded by the screw that mounts it to the frame--don't trust that. Run a short ground wire from inside the housing to a separate ground bolt in the frame, and scrape/sand away the paint under the connection. You can paint over the bare metal *after* it's in place.

Likewise check that the tow vehicle receptacle white wire is connected to a *clean* solid part of the frame, or tapped into a known-good ground wire in the lights harness.

 

[04fxdwgi25]

Sorry for the bad photo quality, but as you can see this is the tester with the turn signals on, but not the tail, I did have my truck lights on also.

1st question, what kind of truck is it? Each type of truck has it's own quirks, so need to know that.

It sounds like your truck is the problem. Can be multiple fuses going to that connector plus, the 12V outputs to the connector could be controlled by the Body Control Module (BCM)

There is usually a connector behind the bumper that connects that trailer connector to the truck harness, They can, and, and do, get corrosion in them. Take it apart and see if it's clean, then clean it again, use some dielectric grease and reassemble and retest.

 

[briangcc]

What tow vehicle? Some vehicles have an inline adapter box which the pigtail runs into and that adapter box does go bad. My '95 Pathfinder had one and it went bad taking with it I think one of the turn signals. Ended up replacing it to restore functionality.

You might want to dig into your tow vehicle to see if it has one.

 

[nicholasgoodman]

What tow vehicle? Some vehicles have an inline adapter box which the pigtail runs into and that adapter box does go bad. My '95 Pathfinder had one and it went bad taking with it I think one of the turn signals. Ended up replacing it to restore functionality.

You might want to dig into your tow vehicle to see if it has one.

It’s a GMC Canyon. I checked the fuses, they’re still good. At the bed of the truck the wires run into a 7pin and 4 pin adapter combo, that comes out next to the license plate. Would that be the adapter box? This is the part I am talking about. I tested the 4 pins with another tester today, still just getting the two turn signals and no running lights. So it definitely is in the truck this time.

 

[brodmann]

I drive a Chevy Colorado and have had to replace my adapter box about every 2 years. Most auto parts stores actually have them in stock or you can buy from Amazon. I think the manufacturer is the same either way. There's a lot that goes on inside that box.

 

[nicholasgoodman]

Just to clarify is the adapter box the thing in the picture I posted?

 

[nicholasgoodman]

I drive a Chevy Colorado and have had to replace my adapter box about every 2 years. Most auto parts stores actually have them in stock or you can buy from Amazon. I think the manufacturer is the same either way. There's a lot that goes on inside that box.

Just to clarify is the adapter box the thing in the picture I posted?

 

[nicholasgoodman]

Does anyone know if this is the adapter box?

 

[briangcc]

Nope. That's not it. That's just the wiring connector.

https://www.etrailer.com/Custom-Fit-Vehicle-Wiring/Dodge/Durango/2022/C56336.html?VehicleID=202261728

See the black box with all the wires running to/from? That's the adapter box I'm referring to. You'll need to dig to see if your vehicle has this or not.