2021 1500 camper/cap wiring issues?

Bpgood1 · December 28, 2020

I read on a thread here that some people had issues with camper shell/cap wiring for 3rd brake light and dome lights in the cap.

I have a leer 100xq on order and someone had mentioned that leer makes a plug and play harness..

The info I'm coming up with is that the harness p/n# 300100 isn't compatible with 2020+ advanced trailering package. Does anyone have a camper shell with advanced trailering package? Any insight as to how your wiring was hooked up?

The last thing I want is to let some kid hack into my factory harnesses and get some dash lights or warnings. I would also like to be hooked to constant batt+ for the dome light, so I dont have to have the running lights on.

Thanks in advance!

2021 Trail Boss LT 1500

Edited December 28, 2020 by Bpgood1

Blue5.3l · December 28, 2020

16 hours ago, Bpgood1 said:

I read on a thread here that some people had issues with camper shell/cap wiring for 3rd brake light and dome lights in the cap.

I have a leer 100xq on order and someone had mentioned that leer makes a plug and play harness..

The info I'm coming up with is that the harness p/n# 300100 isn't compatible with 2020+ advanced trailering package. Does anyone have a camper shell with advanced trailering package? Any insight as to how your wiring was hooked up?

The last thing I want is to let some kid hack into my factory harnesses and get some dash lights or warnings. I would also like to be hooked to constant batt+ for the dome light, so I dont have to have the running lights on.

Thanks in advance!

2021 Trail Boss LT 1500

I have a cap also ordered for my 2021 SLT premium plus and was told with the harness it will be plug and play. The websites just aren’t up to date yet. Some dealers are also clueless and people are cheap. Some won’t pay the extra money for the harness. The 2019 models did have a problem but is now fixed. I have a cap currently on my 2018 SLT premium plus so I don’t foresee a problem. The dealer was knowledgeable then and still knew what he had to do on the new body style when I asked. I called around and was surprised by the people still confused about these trucks. Current cap has a switch for the dome light. The new cap will have the dome light on when the rear glass is open.

Bpgood1 · December 28, 2020

27 minutes ago, Blue5.3l said:

I have a cap also ordered for my 2021 SLT premium plus and was told with the harness it will be plug and play. The websites just aren’t up to date yet. Some dealers are also clueless and people are cheap. Some won’t pay the extra money for the harness. The 2019 models did have a problem but is now fixed. I have a cap currently on my 2018 SLT premium plus so I don’t foresee a problem. The dealer was knowledgeable then and still knew what he had to do on the new body style when I asked. I called around and was surprised by the people still confused about these trucks. Current cap has a switch for the dome light. The new cap will have the dome light on when the rear glass is open.

Via the leer dealer and the packaging on the harness, it specifically excludes the 20 and up GM models with "advanced trailering package" does your truck have this option? It's a specific add on.

For what it's worth the leer dealer I'm using was aware of what I was talking about and specified that the harness doesnt fit 20 & 21 MY with the "advanced trailering"

Edited December 28, 2020 by Bpgood1

Blue5.3l · December 28, 2020

28 minutes ago, Bpgood1 said:

Via the leer dealer and the packaging on the harness, it specifically excludes the 20 and up GM models with "advanced trailering package" does your truck have this option? It's a specific add on.

For what it's worth the leer dealer I'm using was aware of what I was talking about and specified that the harness doesnt fit 20 & 21 MY with the "advanced trailering"

Looking at the Chevy site my truck will have everything the advance trailing package has. Will have to wait and see what happens when the cap comes in. Two of the dealers I deal with said plug and play was possible. LED tail lights make it harder to wire but a harness makes it easier from what I’m being told.

Bpgood1 · December 28, 2020

Hmm I hope I can utilize the plug n play, but not looking likely. The only available info seems to be a definite no for the short harness. I am hoping someone else steps in with a good answer that has already dealt with this. Thanks Blue5.3 for the insight and good luck with your cap install

Edited December 30, 2020 by Bpgood1

Bpgood1 · December 30, 2020

So I got a definitive answer. The harness is absolutely not a plug and play with Advanced Trailering option. Specifically it can not support the "pass through view" of the trailer, which is exclusive to the advanced package. If you plug the harness in and attempt to use it, you will supposedly get an error message in the DIC.

I received a diagram of where Leer recommends the dealers pick up the stop lamp signal. I personally intend to run my own wire for the brakes. I will also have wires ready direct from battery for ground and constant power to use the dome light on demand.

Blue5.3l · January 30, 2021

On 12/29/2020 at 6:38 PM, Bpgood1 said:

So I got a definitive answer. The harness is absolutely not a plug and play with Advanced Trailering option. Specifically it can not support the "pass through view" of the trailer, which is exclusive to the advanced package. If you plug the harness in and attempt to use it, you will supposedly get an error message in the DIC.

I received a diagram of where Leer recommends the dealers pick up the stop lamp signal. I personally intend to run my own wire for the brakes. I will also have wires ready direct from battery for ground and constant power to use the dome light on demand.

Did you ever get your cap and get the wiring straightened out? My last cap had the option of the factory key unlocking the glass. Did you get that option?

Bpgood1 · January 30, 2021

I did not get the keyless entry on the cap. I did figure out my wiring and could offer a detailed description to anyone in need

Blue5.3l · January 30, 2021

16 minutes ago, Bpgood1 said:

I did not get the keyless entry on the cap. I did figure out my wiring and could offer a detailed description to anyone in need

Could you post what your dealer gave you?

Bpgood1 · January 30, 2021

I could do that no problem. They simply sent a pic of the plug on the BCM that houses the 3rd brake wire. I found a much more favorable location to splice the wire (in my opinion anyway)

redwngr · January 30, 2021

They can likely make the 3rd stop light work, but perhaps the problem is the camera(s) in the CHMSL.....?

Edited January 30, 2021 by redwngr

Bpgood1 · January 30, 2021

28 minutes ago, redwngr said:

They can likely make the 3rd stop light work, but perhaps the problem is the camera(s) in the CHMSL.....?

No sir, my truck doesnt have that camera option. The problem lies specifically with the trailering app. More specifically it only affects the advanced trailering package.

I picked up the CHMSL wire under the glove box. That is where the connector for the whole headliner plugs in at. I cut the CHMSL wire at that location and spliced a new one on, I tied another wire in to a existing ground about 10 inches away and used a body grommet that was in the floor.

I ran those 2 wires ( in loom) to the rear of the truck. Dropped the spare tire and picked up a B+ wire off the 7 pin trailer connector. From there i took all 3 wires up through the left tail lamp pocket and up through an existing hole in the bedside.

It works perfectly. No issues at all, and a very clean neat looking job

Bpgood1 · February 4, 2021

Bpgood1 · February 4, 2021

BigdaddyoCan · April 3, 2021

I just bought a 2021 1500 LT so this is very interesting to me too as I am going cap shopping. I do not ahve advanced trailering so do I need to be concerned on wiring still? Kinda nervous as it a big leap from my 2006 to 2021 and I hear all these wiring issues that can pop up. The above seems to be for a 2019 but what should I be asking to make sure they know what they are doing? Testing y trailer hookups before I get the cap this weekend so really want to make sure they wire it right once I get one.