2019 RAM 1500 - Can I add this now?

The window repair shop installed a Heated Rear window instead of a simple privacy glass window. My truck did not come with a wiring kit for that, can it be added now that I have the heated rear window?

I do not see any reason why it could not be done. as long as the proper size wire is used along with fuse, relay, and switch using soldered connections and heat shrink wrap them. I suggest you use a reliable shop to have it done.

Seems like it should be possible. One caution, takes quite a bit of power, so this will create an add’l load on the alternator. So you might run into alternator/battery problems, and you may notice the engine stalls when you turn the rear defogger on. When that gadget comes w/the car new, there’s usually a method for the computer to increase the engine rpm slightly when the rear defogger is turned on.

Thanks for the feedback, it’s appreciated.

That never happens.

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Truck is 3 yrs old. You’ve made it this far with no defogger. Do you need one?

Quick search shows 10 amps. I would tap into the fuse box and run a separate circuit. Not the easiest, but certainly the best choice as an extra 10 amps could kill anything you tap into. It is possible there is a circuit in place, check the fusebox readout in case it was an option not installed. If so then you will just need a jumper wire, and probably a control switch.

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The wiring might already be there. Dodge may have found it cheaper to wire the truck for accessories like the rear window defogger even if the wired window wasn’t originally installed. If none of the mechanics here know for sure, as at the Dodge dealer parts counter. They will certainly have the OEM switch to control the rear defogger.


The OEM hvac control panel with the rear defrost switch is $363, likely a special order item. Plus a couple hours of labor, perhaps $1000 total for a rear defroster.

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You can purchase an aftermarket switch with a built-in timer. That’s what I would use.

It would almost surely be cheaper for the manufacturer to design and produce just one type of wiring harness, rather than produce different harnesses for all of the variations that were available in regard to options.

The upscale version of my Corolla had a trunk-light option. Thought it might be worthwhile to add a light back there that would turn on when I opened the trunk, thinking a bulb socket and mercury switch is all I need. There’s unused wiring and connectors in the engine compartment presumably for non-existent AC, so looked for corresponding unused power wires in the trunk area. Zilch. That part of the wiring harness apparently wasn’t installed unless the car had the trunk-light option.