Added LED rear strip defeats parking sensor

[H20ENG]

 I added an LED strip under the tailgate with tail/brake/turn/reverse lights. I ordered the truck with the 5th wheel wiring prep so wired the strip directly to the 5th wheel wiring, where the 7 pin plug would go. It popped up as a "Trailer Connected" on the DIC so I chose "Accessory Only" on the trailering app.  Then no issues.

 

 Since my Covid-build truck delivered without a few things, I didn't have rear parking sensors for a while. After the dealer installed the rear sensors, the DIC says "Rear parking sensors disabled" (or similar, its not in front of me) whenever I go into reverse. 

 

 I have taken it in to the dealer twice, and they can only tell me the truck thinks there is a trailer connected so defeats the sensors, though it is set to accessory only and does not show a trailer on the app. I keep insisting that this is why there is an "Accessory Only" item on the menu and it should work as such. Seems to me a software issue. When they unplug the 5th wheel harness the sensors work fine so they refuse to do anything further.

 

 The only way I can see to remedy at this point is to tap into the taillight wires, which is a PITA vs where I wired it originally.

Anybody else run into this or have any ideas?

 Thanks!

[Another JR]

Yes I discovered this behavior on my 2021 3500 SLT when i first connected to the trailer connector for the marker lights on my bed-length camper. I only needed the markers to come on when the truck’s marker lights are on, and did not need any other connections via the trailer connector. It quickly became clear that there was no fooling the trailer connection computer.
 

I just tied into the left rear fender marker lamp wire for the camper marker lights and the truck doesn’t know the camper is there, so all the safety features remain operative.  I chose that location because it was easy to access and I can replace that spliced two-foot-long single wire section with an OEM part and put it back to original easily. 
 

Your setup sounds like you would need most of the light connections to make all of your light bar features work. That is a bunch of splicing that may not be easily reversed. 
 

Parking assist is nice, but I especially like the cross traffic alert in reverse and would not want to give that up. 
 

If it was me I would get rid of the light bar, but you’ll have to decide how important it is to you. 

[gemarsh]

You don't mention what brand of light bar, but the putco comes with a gm specific wiring harness that tee's into the 7way for power and then tee's into the left and right tail lights, so it doesn't wonk out the bcm.

 

That harness is available separately. 

[newdude]

36 minutes ago, gemarsh said:

You don't mention what brand of light bar, but the putco comes with a gm specific wiring harness that tee's into the 7way for power and then tee's into the left and right tail lights, so it doesn't wonk out the bcm.

 

That harness is available separately. 

 

 

Bingo.  

[Crazy Canuck]

No help with the problem but I sometimes wonder if the 'trailer computer' among other things has made life easier for anyone...

[gemarsh]

11 hours ago, Crazy Canuck said:

No help with the problem but I sometimes wonder if the 'trailer computer' among other things has made life easier for anyone...

It does make checking the trailer lights easier. 

[carkhz316]

On 12/31/2024 at 8:01 PM, gemarsh said:

It does make checking the trailer lights easier. 

I'm all for added convenience for things that bolster safety, but heck its as simple as: turn headlights on, press hazard button. Now walk to the back of trailer. What I've done for years.