Work Around For trailer disconnect

[Tomski12]

I have a 2022 sierra with the Duramax 3.0 and the max tow package. I have a brand new boat with a brand new boat mate trailer.  I took my truck in a few weeks ago to have this issue checked out. They told me the trailer light module had a short so they had to replace it.  They ordered it. It took a week to come in and another week to get me set for an appointment. Today the tech says that he didn’t really understand how the trailer system worked so he thought there was a short in the system. But since my truck worked with a box trailer at the dealership he concluded that the truck is fine and did not replace the trailer light module. Well, the trailer that works perfectly fine with my wife’s forerunner and my sons Tacoma does not work with my $70,000 truck with the max tow package. I’m going out on trip tomorrow  over some major mountain passes so the forerunner or the Tacoma will not work. I need my truck to be able to tow this trailer. Does anybody know of a workaround that will allow my truck to see the trailer so that the brake lights work and the surge brakes work. I’m not so concerned about it showing up in the driver information center or the blinker showing up I’m really just concerned with the safety aspect of us right now, thanks in advance. As you might be able to tell from the tenor of this post I am extremely disappointed and upset. My understanding is there is a flaw in the system when it tries to recognize a trailer with LED lights. But my dealership had the foresight or lack there of to put a technician on the truck who has minimal understanding of the tow system.

[PhilB]

Frustrating, I understand.  Have you tried setting up a trailer profile?  I have a bass boat with surge brakes and a horse trailer with electric brakes that I tow.  The last time I towed the horse trailer, I got the message that no trailer was detected.  I ran the trailer light test function and all lights on the horse trailer worked.  I started driving and tested the trailer brake by using the manual trailer brake button and the brake gain would work.  When I got to where I was going and restarted the truck, it recognized the trailer was connected.  Go figure.    

 

Since your trailer has surge brakes, you should be good to go.  Surge brakes will work when you are applying the brakes on the truck.  They do not need an electrical connection to work.  Do the lights work on the trailer when you have it hooked up?  Have you tried using the trailer light test to see if they work?  On my '14 Silverado, I was trying to test the lights on the bass boat during the day and they didn't seem to work.  This was before GM had the brake light test.  Then I realized the sensor on the dash was preventing the lights from coming on.  LOL  I had to put a dark towel over the sensor so I could check the lights.  Don't have to do that now with the trailer light test function.

[Rob Mugs]

Let me guess.... 

 

The trailer is 100% LEDs.

 

First of all, not sure how in the world this would affect surge brakes which are mechanical

Secondly, the LEDs are likely not drawing enough power to trip the system which uses resistance to detect the trailer.

Add a resistor or incandescent bulb inline and test.

Edited July 26, 2023 by Rob Mugs

[MrMagloo]

15 hours ago, Rob Mugs said:

Let me guess.... 

 

The trailer is 100% LEDs.

 

First of all, not sure how in the world this would affect surge brakes which are mechanical

Secondly, the LEDs are likely not drawing enough power to trip the system which uses resistance to detect the trailer.

Add a resistor or incandescent bulb inline and test.

 

While I agree adding some resistance might help - as a quick bandaid, Imho, in this day and age, GM should have the common sense to recognize that more current trailers may very well be all LED.  I would urge that the appropriate route would be to push GM for an update for the appropriate module programming to reduce the base line draw to resolve this glaring issue.

 

 

 

[newdude]

On 7/20/2023 at 10:47 PM, Tomski12 said:

I have a 2022 sierra with the Duramax 3.0 and the max tow package. I have a brand new boat with a brand new boat mate trailer.  I took my truck in a few weeks ago to have this issue checked out. They told me the trailer light module had a short so they had to replace it.  They ordered it. It took a week to come in and another week to get me set for an appointment. Today the tech says that he didn’t really understand how the trailer system worked so he thought there was a short in the system. But since my truck worked with a box trailer at the dealership he concluded that the truck is fine and did not replace the trailer light module. Well, the trailer that works perfectly fine with my wife’s forerunner and my sons Tacoma does not work with my $70,000 truck with the max tow package. I’m going out on trip tomorrow  over some major mountain passes so the forerunner or the Tacoma will not work. I need my truck to be able to tow this trailer. Does anybody know of a workaround that will allow my truck to see the trailer so that the brake lights work and the surge brakes work. I’m not so concerned about it showing up in the driver information center or the blinker showing up I’m really just concerned with the safety aspect of us right now, thanks in advance. As you might be able to tell from the tenor of this post I am extremely disappointed and upset. My understanding is there is a flaw in the system when it tries to recognize a trailer with LED lights. But my dealership had the foresight or lack there of to put a technician on the truck who has minimal understanding of the tow system.

 

 

Assuming the trailer lighting control module is working fine, if your trailer is all LED you may need more load.

 

GM says to use the Curt 57003 load adapter in line with the trailer.  

 

PIT5747B: Diagnostic Tip - Trailer Lighting Complaints With Trailering App RPO U1D

1. Some trailers utilize a trailer mounted control module to operate some or all of the trailer lights. These trailers may use the B+ circuit from the trailer connector to power the trailer lighting circuits. These trailers may not always be detected by the Trailer Lighting Control Module and may set faults. Possible ways to remedy this:

   A. Load resistors could be added in parallel to the detectable lighting circuits of the trailer, which will increase current draw.  One known source is the Curt brand Trailer Wiring Adaptor P/N 57003, which can be plugged inline with the 7 way trailer connector.  This adaptor can be used to simulate additional lighting load, allowing the K68 Trailer Lighting Control Module to detect the trailer, however some circuit diagnostics and bulb outage detection will not be possible.  The addition of a load resistor/adaptor will be at the customer's/trailer manufacture's discretion.

2. B. The customer's trailer will need to be rewired to eliminate the trailer mounted control module and have the circuits wired directly to the trailer lamps.  This option would allow for the K68 Trailer Lighting Control Module to properly detect the trailer and provide full system features such as, trailer detection,  trailer theft, trailer lighting circuit diagnostics, and trailer bulb outage detection. This repair will be at the customer's/trailer manufacture's discretion. 

3. Some non–DOT approved LED lamps may not draw enough current for the K68 Trailer Lighting Control Module to detect a trailer when connected, and the K68 Trailer Lighting Control Module will not enable the lighting circuits to the trailer. Possible ways to remedy this:

   A. Change one or more trailer lamps on the detectable circuits to incandescent bulbs/ DOT-approved LED lamps to increase the current draw which will maintain full functionality of the K68 Trailer Lighting Control Module.  The addition of incandescent bulbs/ DOT-approved LED lamps will be at the customer's/trailer manufacture's discretion.

   B. A load resistor could be added in parallel to the detectable lighting circuits of the trailer, which will increase current draw. One known source is the Curt brand Trailer Wiring Adaptor P/N 57003, which can be plugged inline with the 7 way trailer connector. This adaptor can be used to simulate additional lighting load allowing the K68 Trailer Lighting Control Module to detect the trailer, however some circuit diagnostics and bulb outage detection will not be possible. The addition of a load resistor/adaptor will be at the customer's/trailer manufacture's discretion.

[MrMagloo]

18 minutes ago, newdude said:

 

 

Assuming the trailer lighting control module is working fine, if your trailer is all LED you may need more load.

 

GM says to use the Curt 57003 load adapter in line with the trailer.  

 

PIT5747B: Diagnostic Tip - Trailer Lighting Complaints With Trailering App RPO U1D

1. Some trailers utilize a trailer mounted control module to operate some or all of the trailer lights. These trailers may use the B+ circuit from the trailer connector to power the trailer lighting circuits. These trailers may not always be detected by the Trailer Lighting Control Module and may set faults. Possible ways to remedy this:

   A. Load resistors could be added in parallel to the detectable lighting circuits of the trailer, which will increase current draw.  One known source is the Curt brand Trailer Wiring Adaptor P/N 57003, which can be plugged inline with the 7 way trailer connector.  This adaptor can be used to simulate additional lighting load, allowing the K68 Trailer Lighting Control Module to detect the trailer, however some circuit diagnostics and bulb outage detection will not be possible.  The addition of a load resistor/adaptor will be at the customer's/trailer manufacture's discretion.

2. B. The customer's trailer will need to be rewired to eliminate the trailer mounted control module and have the circuits wired directly to the trailer lamps.  This option would allow for the K68 Trailer Lighting Control Module to properly detect the trailer and provide full system features such as, trailer detection,  trailer theft, trailer lighting circuit diagnostics, and trailer bulb outage detection. This repair will be at the customer's/trailer manufacture's discretion. 

3. Some non–DOT approved LED lamps may not draw enough current for the K68 Trailer Lighting Control Module to detect a trailer when connected, and the K68 Trailer Lighting Control Module will not enable the lighting circuits to the trailer. Possible ways to remedy this:

   A. Change one or more trailer lamps on the detectable circuits to incandescent bulbs/ DOT-approved LED lamps to increase the current draw which will maintain full functionality of the K68 Trailer Lighting Control Module.  The addition of incandescent bulbs/ DOT-approved LED lamps will be at the customer's/trailer manufacture's discretion.

   B. A load resistor could be added in parallel to the detectable lighting circuits of the trailer, which will increase current draw. One known source is the Curt brand Trailer Wiring Adaptor P/N 57003, which can be plugged inline with the 7 way trailer connector. This adaptor can be used to simulate additional lighting load allowing the K68 Trailer Lighting Control Module to detect the trailer, however some circuit diagnostics and bulb outage detection will not be possible. The addition of a load resistor/adaptor will be at the customer's/trailer manufacture's discretion.

 

Thank you for sharing.  While it's nice that GM is recognizing THEIR problem, seeing the entire automotive industry is going LED makes a bandaid solution, especially at the owners expense a questionable response.  I'm not sure myself if the BCM controls the K68, or if that is individually programmable, but the appropriate response is to reprogram the sensitivity to account for all LEDs and the inherent lighter resistance load.  To suggest it's the customers fault is a little off base, imho.

 

Alternatively, they can source the 57003 and cover the install for those affected during the 3 year warranty period.  If you purchase a trailing package, it should be updated enough to handle the modern trailers made during the last 4-5 years.  Silly position.

Edited July 26, 2023 by MrMagloo

[newdude]

25 minutes ago, MrMagloo said:

 

Thank you for sharing.  While it's nice that GM is recognizing THEIR problem, seeing the entire automotive industry is going LED makes a bandaid solution, especially at the owners expense a questionable response.  I'm not sure myself if the BCM controls the K68, or if that is individually programmable, but the appropriate response is to reprogram the sensitivity to account for all LEDs and the inherent lighter resistance load.  To suggest it's the customers fault is a little off base, imho.

 

Alternatively, they can source the 57003 and cover the install for those affected during the 3 year warranty period.  If you purchase a trailing package, it should be updated enough to handle the modern trailers made during the last 4-5 years.  Silly position.

 

 

Notice however they talk about non DOT approved lighting.  If the trailer companies are just slapping on LEDs as cheap as possible, then its on the trailer companies not GM.  Not everyone runs out and buys new trailers either.  

[MrMagloo]

Just now, newdude said:

 

 

Notice however they talk about non DOT approved lighting.  If the trailer companies are just slapping on LEDs as cheap as possible, then its on the trailer companies not GM.  Not everyone runs out and buys new trailers either.  

 

Agreed - that is a very important distinction.  GM shouldn't be held responsible for any non approved lighting, especially aftermarket retrofits.  But, any newer trailer that came stock from the OEM with DOT lighting should be compatible.

 

I will mention that I recently rented a virtually new tandem U-Haul with 100% LED's and they worked fine.  But, there was a weird glitch where after I parked the truck, the LED's blinked all night long.  Not being parked in the best part of this town, it did concern me that it was drawing attention.  As we know, that is part of the anti-theft feature, but still irritating nonetheless.

 

 

 

[gemarsh]

1 hour ago, MrMagloo said:

 

Agreed - that is a very important distinction.  GM shouldn't be held responsible for any non approved lighting, especially aftermarket retrofits.  But, any newer trailer that came stock from the OEM with DOT lighting should be compatible.

 

I will mention that I recently rented a virtually new tandem U-Haul with 100% LED's and they worked fine.  But, there was a weird glitch where after I parked the truck, the LED's blinked all night long.  Not being parked in the best part of this town, it did concern me that it was drawing attention.  As we know, that is part of the anti-theft feature, but still irritating nonetheless.

 

 

 

The blinking anti-theft feature can be turned off in the trucks trailering app.

[MrMagloo]

10 minutes ago, gemarsh said:

The blinking anti-theft feature can be turned off in the trucks trailering app.

 

I think you mean the Anti-Theft feature itself can be turned off.  But the blinking while engaged is a flaw.  You certainly do not want to be drawing attention to an unprotected trailer with flashing lights all night long.  You shouldn't have to disengage the feature to avoid the attention getting flashing.

 

 

[gemarsh]

3 hours ago, MrMagloo said:

 

I think you mean the Anti-Theft feature itself can be turned off.  But the blinking while engaged is a flaw.  You certainly do not want to be drawing attention to an unprotected trailer with flashing lights all night long.  You shouldn't have to disengage the feature to avoid the attention getting flashing.

 

 

True.

 

I don't know how gm could do it differently though. They could cycle the electric brakes, but not all trailers have brakes.

 

gm flashes the lights to get a current draw reading, allowing the truck to "see" if the trailer is still attached.

[GETGONE]

I had a 2017 Wells Cargo 6x12 enclosed cargo trailer with all LED lighting and had no issues with my 21 Trail Boss Custom. It was a flat 4 trailer plug though. Is your boat trailer a 7 way plug? I have yet to tow a trailer with a 7 way connector.

[MrMagloo]

13 hours ago, gemarsh said:

True.

 

I don't know how gm could do it differently though. They could cycle the electric brakes, but not all trailers have brakes.

 

gm flashes the lights to get a current draw reading, allowing the truck to "see" if the trailer is still attached.

 

Yeah, I'm not sure what the lowest possible current is that will allow an accurate read, but it certainly can use some downward adjustment testing. Clearly they are using a pulse width and voltage that is fine for incandescent, but is far too slow, too high of voltage not to trigger LED's.  GM is smart enough to figure this out. 

Edited July 27, 2023 by MrMagloo

[Rob Mugs]

On 7/27/2023 at 9:34 AM, MrMagloo said:

 

GM is smart enough to figure this out. 

I agreed until this line.

 

This has been a "thing" for many years on these trucks.  My early 2020 had it and my 23 has it.  I believe it goes back even further.

 

I drove a Ford the other day and honestly, the technology is like comparing a flip phone to a modern day smart phone.  It's much more refined.  From the trailering functions to the lane keep assist.  It all just blends into the background.  Once I have built a little equity in this truck, there's a very real possibility I'll be making the move

[MrMagloo]

On 7/29/2023 at 9:11 PM, Rob Mugs said:

I agreed until this line.

 

This has been a "thing" for many years on these trucks.  My early 2020 had it and my 23 has it.  I believe it goes back even further.

 

I drove a Ford the other day and honestly, the technology is like comparing a flip phone to a modern day smart phone.  It's much more refined.  From the trailering functions to the lane keep assist.  It all just blends into the background.  Once I have built a little equity in this truck, there's a very real possibility I'll be making the move

 

Well, maybe not?  Perhaps one of the friendly GM Support folks that drift around the forum can take this up?