Why?

As long as they're intermittent nuisance failures and not hard faults it should be just fine. Plug in a trailer without a relay kit and things will get interesting, but that's an additional load I recommended against.

PS: The hot ticket, and what I would do if it were mine, would be to install a relay that adds only coil current to the park light circuit and connects the clearance lamps via a suitable fuse to the battery positive terminal. But he should be okay adding the lamps and no additional loads.

 

What I would be willing to do personally, and what I would consider advisable are often different.
In this case though what I would recommend, and do are one in the same.

Swap out the overheads bulb for LED due to them being lower consumption, longer lifespan, and brighter bulbs in general. In addition I would wire them directly into the parking light circuit since it is a lower load circuit to begin with.
Since they do make a dual circuit type led bulb upgrade (to accommodate run/blinker or HI/LOW functions) I would even go as far as to tie the outermost opposing pair to the turn relay.
Of course I am not shy or even the least bit threatened by electricity electronics,wiring, and circuitry (home or auto). My brass has gotten me lit up like a christmas tree more times than I care to admit, pun definitely intended.

 

Dodge is a corporation, in it to make money. It goes without saying that they are going to skimp as much as possible. I am sure that the wire gauge is the same in the harness for trucks with or without the clearance lights. (I have not checked yet). But that doesn't mean that it was sized with any fudge-factor built into it. Adding a larger fuse, possibly of a size larger than the wire itself, means that the wire will now become the new fuse point.

If you concur that the headlight relay mod is a good update, then you must feel that it is, indeed, a good idea to reduce the current load through the light switch (and associated wiring). Why advocate for putting more through it now?

I am not telling you anything that you do not already know, that is why I am surprised.

Personally, I would do either LEDs in the clearance lights or a separate relay.
And, I put LEDs in throughout the truck, specifically to reduce the current load in this inherently weak system already.

 

It's AWG16; the ten second fusing current for solid AWG16 is over 100A, and the one second fusing current is right around 400A. It's greater fuse currents for stranded conductors, but the values depend upon the strand diameter and count... I always design for solid conductor anyway so some future repair can't create a fire hazard.

I'm a-guessin' that after adding five 157 lamps (which are what the factory would have installed for cab roof marker lights) that circuit is going to see right around 5.25A, steady state, and that cold filament startup with the additional lamps is not going to open the factory's 20A fuse anyway. If it does, it'll be just barely, and not often. As for steady state conductor power dissipation, it'd be just over 20mW/ft so nothing to worry about.

Does my thinking still seem incongruous to you?

 

No. Good thing to know its 16ga. I was figuring about an additional 2 amp draw, which is mostly insignificant. But, again, why chance it.

And, you still have the light switch issue (where all of the current is going through it). To me, whomever designed that circuit did not have a brainstorm but was brain-dead.

 

I second that! You would think that Chrysler would have learned their lesson after all the electrical issues they had with the first gen trucks. Burnt amp wiring, burnt wires/terminals on the bulkhead disconnect etc... I heard there was a recall for the second gen fan wiring also.

 

That's about right. They're 4.9W per 157 lamp. But we surely have thrown a lot of words at "mostly insignificant"!

I guess that's what web forums are for, eh?