Wiring from engine bay to roof

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prharper

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Looking to add 2 small Baja Design S2 lights to the rear of my roof rack. Due to my existing wiring configuration, I'm not interested in running anymore power from engine bay Switch Pro thru the cabin and out the back door grommets again. Been there, done that and probably too tight to run more cable thru those two looms.

What seems like the easy button is to run new power from engine bay up driver's side windshield channel or underneath moulding. I did some research on here looking at a few different related threads.

I was looking to run a 14GA wire pair up the windshield moulding ideally under the plastic trim. Appears some of the earlier 200's have slightly different mouldings and space tolerances.
@2001LC @grinchy @radman stumbled on this earlier.

Knowing this, I figured it would be good to take apart and evaluate my routing options on my 2018 LC. Learned you need to remove the side moulding in engine bay and then remove wipers and the cowl. Did that, wasn't too bad. Getting the windshield moulding off without breaking clips took some effort and patience.

Good thread below by @2001LC which helped me avoid breaking any of the plastic clips.

Started at the top with the 2 metal clips that are glued to the roof channel. The first metal clip came off. Managed to get it detached from the second metal clip but it later came separated from the roof - epoxy gave out.

Some observations:
Didn't realize there is a plastic section that sits in the roof channel that connects to the two metal clips that are glued to roof (mine came off). The rubber molding is on top and connects to this plastic section.
IMG_6200.jpeg

Could not believe how much gunk and mud were lodged in there. FWIW - I wash my truck often.

IMG_6199.jpeg



The long rubber moulding piece has plastic bonded to the lower portion to help funnel water to the drain in the cowl. I thought this was a separate part from the cowl and the windshield moulding but it's not. See below.
IMG_6202.jpeg


If I run wiring under this section, it will create a gap between cowl, molding and the windshield. I didn't get a picture with the moulding off showing the plastic clips, but there doesn't appear to be enough space/clearance to get the wiring under the rubber like others have done on earlier 200's. However, there is plenty of space in the channel to run up.

Trying to make this a cleaner install but not sure if that's possible. Same goes for the top section of the rubber moulding. No way to make a clean transition of the cable in the channel and underneath the top moulding section on roof. Will probably do like @grinchy and zip tie to the roof portion of the moulding strip. Curious how @Cruisin911 @CharlieS did theirs awhile back.

Rain was forecasted within the hour or two so bailed, put everything back together - minus the two metal clips that were glued to the roof. Looks like I can reuse them after cleaning up and removing epoxy / resin.
IMG_6209.jpeg


What's Toyota using to glue these down to the roof channel?
 
I used a general purpose adhesive called E6000 to glue down the upper clips that were inadvertently removed during disassembly.

image.jpg


I find it so useful that I both carry it on trips and keep a fresh tube in the home shop.

I found it easy to run a two conductor (14 ga?) tinned marine wire up under the windshield side trim, but mine was a 2013. I haven't tried it on the 2016. This made for an easy roof mounted light bar.
 
Last edited:
Fwiw that lead is still up there and doing fine. It’s been a few years at this point. Moulding still down and zip ties still ok.

Haven’t had a light up there for a while though.
 
I have not run light wires up there yet.. but when I do I'll run an 8 or 10 awg for a common ground, then some extra 14's for future side lights.
 
I have not run light wires up there yet.. but when I do I'll run an 8 or 10 awg for a common ground, then some extra 14's for future side lights.

You'll likely find it difficult to run that much wire. Two 14awg (per side) is about what room there is. Anymore and it'll be a pain to get trim to fit back nicely.
 
I used a general purpose adhesive called E6000 to glue down the upper clips that were inadvertently removed during disassembly.

View attachment 3803314

I find it so useful that I both carry it on trips and keep a fresh tube in the home shop.

I found it easy to run a two conductor (14 ga?) tinned marine wire up under the windshield side trim, but mine was a 2013. I haven't tried it on the 2016. This made for an easy roof mounted light bar.
Thanks
Looking to add 2 small Baja Design S2 lights to the rear of my roof rack. Due to my existing wiring configuration, I'm not interested in running anymore power from engine bay Switch Pro thru the cabin and out the back door grommets again. Been there, done that and probably too tight to run more cable thru those two looms.

What seems like the easy button is to run new power from engine bay up driver's side windshield channel or underneath moulding. I did some research on here looking at a few different related threads.

I was looking to run a 14GA wire pair up the windshield moulding ideally under the plastic trim. Appears some of the earlier 200's have slightly different mouldings and space tolerances.
@2001LC @grinchy @radman stumbled on this earlier.

Knowing this, I figured it would be good to take apart and evaluate my routing options on my 2018 LC. Learned you need to remove the side moulding in engine bay and then remove wipers and the cowl. Did that, wasn't too bad. Getting the windshield moulding off without breaking clips took some effort and patience.

Good thread below by @2001LC which helped me avoid breaking any of the plastic clips.

Started at the top with the 2 metal clips that are glued to the roof channel. The first metal clip came off. Managed to get it detached from the second metal clip but it later came separated from the roof - epoxy gave out.

Some observations:
Didn't realize there is a plastic section that sits in the roof channel that connects to the two metal clips that are glued to roof (mine came off). The rubber molding is on top and connects to this plastic section.
View attachment 3803187
Could not believe how much gunk and mud were lodged in there. FWIW - I wash my truck often.

View attachment 3803191


The long rubber moulding piece has plastic bonded to the lower portion to help funnel water to the drain in the cowl. I thought this was a separate part from the cowl and the windshield moulding but it's not. See below.
View attachment 3803243

If I run wiring under this section, it will create a gap between cowl, molding and the windshield. I didn't get a picture with the moulding off showing the plastic clips, but there doesn't appear to be enough space/clearance to get the wiring under the rubber like others have done on earlier 200's. However, there is plenty of space in the channel to run up.

Trying to make this a cleaner install but not sure if that's possible. Same goes for the top section of the rubber moulding. No way to make a clean transition of the cable in the channel and underneath the top moulding section on roof. Will probably do like @grinchy and zip tie to the roof portion of the moulding strip. Curious how @Cruisin911 @CharlieS did theirs awhile back.

Rain was forecasted within the hour or two so bailed, put everything back together - minus the two metal clips that were glued to the roof. Looks like I can reuse them after cleaning up and removing epoxy / resin.
View attachment 3803284

What's Toyota using to glue these down to the roof channel?
Edit - Found the adhesive part for these in FSM.
1735524040958.png
 
You can also carefully drill 1/8" holes in the flange of the window trim. Place a thin metal backer against the glass so you don't induce a crack from a chip. You can then thread small zip-ties through the holes to secure your roof wiring. I use three holes per side and keep my wire bundles small to tuck almost complete under the trim.

I've found zip-ties degrade under UV and need to be replaced proactively every two years. Or you can wait until they self-relieve and the cable starts slapping the side of the truck at highway speed. ;-)
 
Decided to go a different route with the cable run. Ended up going from engine bay, underneath the truck along frame, behind rear bumper, up rear body and rear hatch, to the rearmost crossbar on roof rack where the 2 lights are mounted. I probably spent more time screwing around with the windshield moulding then running cable on this route. Cable run probably isn't a whole lot longer than If I had gone up the A pillar since it has to go to rear of roof for lights.

For those planning to remove or replace the windshield moulding, I'll pass on some additional info that I could not find online.

The top portion of the moulding has a hard plastic section that attaches to the rubber moulding with 4 metal tabs. This plastic section is what connects to the two metal clips that are glued to the roof. When I removed mine, this piece separated from the moulding (along with the 2 metal clips). I could not find any pics or reference to this. Online parts pics also don't quite show that level of detail. The bottom section is fused to another piece of softer rubber that meets upon against the cowl.

I went ahead and picked up a new moulding from the dealer today along with some metal clips. Now that I know how these pieces fit together, I'll repair the existing moulding top section. Waiting on the 3M epoxy to arrive (and probably warmer weather). Using duct tape for now on that top section to hold it down.

Pics of the parts:
Bottom section that meets up and connects with the cowl.
IMG_6228.jpeg


Top section below. Those 4 metal tabs hold the hard plastic section, it is what snaps in to the metal clips. Mine separated but will reattach by bending the tabs back on to it. This was a mystery part prior to getting a new one to look at.
IMG_6229.jpeg


Lastly, the plastic section snaps into these two clips below. They do come with some type of plastic on the back side. (It's not foam). You glue that side down to the roof with epoxy. Pic includes one that came off and missing some of the plastic/epoxy on back side. Part number also shown in photo.

IMG_6230.jpeg


Latest part number for driver side moulding.

MOULDING, WINDSHIELD, OUTSIDE LH​

75534-60072​

 
Paul, sounds like you have it taken care of now but have you seen the solution from KC Hilites?
Jeff - good callout on that piece. I had run across it somewhere but forgot about it. That would be much easier than messing around with the OEM molding - which I still need to repair weather permitting. Might be waiting until Spring. Lol.
 
You'll likely find it difficult to run that much wire. Two 14awg (per side) is about what room there is. Anymore and it'll be a pain to get trim to fit back nicely.
The key is to use high quality wires with their thinner insulation. While I like to use a lot of Teflzel insulated Mil Spec 22759/16 or /32 (150 deg C rated, great for engine compartment) in 14awg, I find that this aviation wire is very stiff so after running through side silt rear and up quarter panel I then switched over to a TXL (125 C rated) 14awg to run though tailgate grommets and on roof rack runs. I've successfully run four 14 g's per side (2 for lighting power and 2 grounds) along with a solar power on one side and solar ground on the other.
 
Those cables are bad ass. The company I worked for built thousands of wiring harnesses for Blackhawks and Stalions using those cables.
 
The key is to use high quality wires with their thinner insulation. While I like to use a lot of Teflzel insulated Mil Spec 22759/16 or /32 (150 deg C rated, great for engine compartment) in 14awg, I find that this aviation wire is very stiff so after running through side silt rear and up quarter panel I then switched over to a TXL (125 C rated) 14awg to run though tailgate grommets and on roof rack runs. I've successfully run four 14 g's per side (2 for lighting power and 2 grounds) along with a solar power on one side and solar ground on the other.
TXL sounds legit!

I’ve only used GXL for under hood wiring stuff. I can’t remember heat rating, but I think it may be lower than TXL spec’d above.
 
TXL sounds legit!

I’ve only used GXL for under hood wiring stuff. I can’t remember heat rating, but I think it may be lower than TXL spec’d above.
All the xXL's are -40 C to 125 C rated at 60 VDC, XL standing for cross-linked polyethylene tarted for automotive use. The T, G, S prefix relates to insulation thickness, ultra thin, thin and standard respectively. Tefzel (mil-spec M22759/xx) wire is a very very thin insulation using cross-linked tetraflouoethylene (think teflon) rated for -65 C to 150 C and used in aerospace, but negatives are cost and stiffness.
 

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