OE 2016-17 Mopar LED bed light harness for 2018 Laramie - no-flash option
Background: Mopar OE bed lights, harnesses, and wiring changed from 2016-17, to 2018 (2019 DS too?), and now 2019 DT RAMs. I read all three sets of PDF instructions to connect the OE bed light harnesses for these three groups, and the changes in where wires connect suggest that BCM wiring and/or programming are different as well.
With that background I had two issues: 1) I bought a Mopar 2016-17 bed light and harness kit without researching to know that it would not have the switch I wanted for the bed of my 2018 Laramie, and 2) I discovered that the instructions miss out and gloss over some really awkward parts of the installation: Four items instead of one that I needed to remove from the steering kick panel, and no indication of an amp and several wire looms blocking access to my truck’s BCM. I ordered the bed light switch as a separate part (P/N 68367545AA,– momentary contact switch), but of course it was not wired into the harness as the case for the 2018 harness. This turned out to be a blessing in disguise, because knowing I needed to add extra wire(s) to the harness made me think harder.
What I did: My BCM is VERY hard to access without removing an amp and some other stuff – your truck build may differ, but I decided not to waste time and risk messing up. The cabin cargo button on the headlight multi-switch works by momentarily connecting pin 6 (cargo light signal) to pin 3 (headlight switch MUX return). To wire the bed switch I used 20 feet of 18 gauge twisted pair wire – 20 feet of wire is the bare minimum length for this on my 2018 Laramie CC short bed, while 18 gauge is oversize. I crimped, soldered & shrink-wrapped my twisted pair wire to the switch, and I ran it together with the Mopar 2016-17 bed light harness from back to front per instructions. At the front I ran the power lead and the twisted pair into the cabin through the firewall grommet, and I connected the ground lead to the M6 (10mm nut) chassis ground stud near the battery. In the dash I spliced the twisted pair wires from the bed switch (crimp, solder, & heat shrink) onto the leads for pin 6 and pin 3 at the headlight switch connector. I ran the bed light power lead down to the main wire harness running along the driver door sill, and I spliced the bed light lead to the cargo light power lead there (crimp, solder, & heat shrink).
Result: My new bed and existing cabin switches are in parallel, and either one triggers the MUX return. This way the Bed Switch mimics the factory behavior, and I can leave the BCM undisturbed for now. The OE LED bed lights do not overload the circuit, but I’ll be converting the cargo lights to LED any way.
THANKS for comments that helped guide my choice !