I’ve been browsing around on here for awhile but I’ve never needed to post until now. I have a 2004 ranger that I just built a flatbed for. I’m trying to wire my led tail lights and I’m having an issue grounding to the frame. If I touch the ground wire for the lights to the frame the light is dull and barely comes on. I’ve tried several spots including the new bolts I put in to hold the bed down and eventually I tapped into the ground wire for the tail light on top of the cab because I plan on running with it off anyway and the lights light up bright like they’re supposed to. I’m new to working on vehicles so I’m sure it’s something simple that I don’t know about. Thanks guys!

 

Welcome to your 1st post on the forum

Is the frame grounded to the battery negative?

The engine and trans are grounded to battery but they sit on RUBBER mounts, so no ground to frame there

The engine has a ground strap to the cab's firewall, but the cab sits on RUBBER mounts so no ground there to frame

And all the body parts are painted FIRST and then assembled at the factory, so no bare metal grounds there either

Anyway, point is, maybe when you took off the bed there was a ground strap that got removed.

You just need to find a ground point in the engine bay and ground it to the frame up front so you will have a good ground in the back
There is usually a good ground point by the battery to Rad support, for head light grounds, and just a short jump down to the frame from there

Make sure its bare metal, you can paint it after its installed

 

I had no idea that everything sits on the frame with rubber mounts. That’s what had me confused how it was possible for the frame not to be grounded but it all makes sense now. I found one of the wires that’s part of the tail light harness that’s a ground so I’ll probably end up running my lights to that. I’ll look into running a ground strap to the frame though it’d be nice to be able to ground my lights to the frame of the bed instead of joining all the wires together. Thanks a lot for your help!

 

You can just run a ground strap to the bed frame, then its a good ground, its a circuit, any metal part you want to be a good ground needs to be connected to battery negative terminal, either directly or thru other metal parts that are already connected to battery negative

In example

Battery Neg--------engine----frame-------------------------------------bed-----tail lights

or

Battery Neg--------frame--------------------------------------------------bed------tail lights

Its good to ground the frame in the engine bay, because it runs the length of the vehicle and you can tap into that ground any where along its length

 

I ended up crimping an eyelet to the ground wire on the tail light harness and running a self tapper holding it into the bed frame. Whenever I get more time to work on it I’ll run a ground strap from the battery to the frame like you said. I have almost zero experience working on vehicles and doing electrical work as you can probably tell lol. Thank you for the help I appreciate it!

 

You don't need to, if that worked, frame is already grounded