No power to trailer lights

[littlethorn]

It crossed my mind that I may have too much draw on my running lights circuit because of the I sec flash then they go out, like the truck is sensing a large draw and shutting down. I have a lot of lights 19 small lights plus 2 tail lights. most forums talk about too little draw because of led's but maybe I have too much. Maybe I'll try disconnecting some lights if that works I'll go to dealer for reprogram. maybe I can mix led's although I think its not recommended. thanks for all the help.

[littlethorn]

29 minutes ago, littlethorn said:

It crossed my mind that I may have too much draw on my running lights circuit because of the I sec flash then they go out, like the truck is sensing a large draw and shutting down. I have a lot of lights 19 small lights plus 2 tail lights. most forums talk about too little draw because of led's but maybe I have too much. Maybe I'll try disconnecting some lights if that works I'll go to dealer for reprogram. maybe I can mix led's although I think its not recommended. thanks for all the help.

 

[littlethorn]

It crossed my mine that I might have too much draw because lights flash on for a sec. like the truck senses the draw and shuts off power. maybe I'll try disconnecting some lights. If that works I'll bring to dealer for module reprogram. thanks for all the help.

[Broccoli Rob]

I had the same issue on both 4 and 7 pin connectors. I tried two trailers, a set of tow lights and put a meter on it but I was getting no juice.  Connectors were good and fuses were good so I took it in to the dealer.  Four hours later, I had a "new harness" as apparently some wiring harness that that fed power to the trailer lights had a grounding issue.  A PITA, but all fixed now.

[littlethorn]

my problem is different apparently in new gmc's too little draw from led lights  or too much from incandescent causes truck computer to not send power to tail light connection. my trailer has about 20 running lights, I disconnected about 10 connected truck and the rest lit up, so I plugged in one at a time and they lit until I got to 16 then they all went off. tried switching different lights in case it was I short but would light at 16 but no more no matter where they were. ordered some led's to substitute about 10 incandescents, hoping they draw soo little it will work. hope they will work together.

[littlethorn]

rsktm300xcw you were right. I tried disconnecting 10 running lights and the rest lit up. I plugged in one at a time and they lite until I had 4 left then they all went out, unplugged  different lights will work with any 4 unplugged so I ordered some led's to substitute incandescents hope this will work.

[Rsktm300xcw]

I believe the reprogram of the trailer light module widens the acceptable amperage draw and may help with this problem. Not positive though. I know that after changing all running lights to led problem was solved. Then I changed brake / tail lights to led problems arose due to too little draw. I added the resistors and all working at this time. Reprogram also helped with trailer disconnected issue.

[Christopher Murphy]

2020 Chevy 2500HD at the dealer for none of my trailer lights working. Brake controller works fine.

I just tested amp draw from RV trailer at right around 4amps. 
13-192 marker lights 

1- license plate light 

2- 3457 brake stop tail lights
seems this should be more than under any programming safety limit. Should know shortly what they come up with. 
worked fine with three trailers with LED lights so I can’t imagine the new trucks only allow new led lights that draw less amps.

 

Edited December 11, 2019 by Christopher Murphy

[Stan Fister]

Has anyone solved the problem with running lights not working but all other trailer lights work dealership and trailer repair can’t solve. Trailer lights work fine when connected to other trucks. My truck is a 2019 Silverado. Please help. Email at [email protected]

or text me 859-361-9531. I need my trailer for work and it’s killing me. Thank you

 

[Stan Fister]

Has anyone solved the problem with running lights not working but all other trailer lights work dealership and trailer repair can’t solve. Trailer lights work fine when connected to other trucks. My truck is a 2019 Silverado. Please help. Email at [email protected]

or text me 859-361-9531. I need my trailer for work and it’s killing me. Thank you

 

[D-Rob]

I had the same problem with my 2018 Silverado. I hooked up my trailer lights to my wife’s car and they worked fine, when I plug them into my truck they wouldn’t work and even blew three fuses under the hood. I finally figured out that a ground wire needs to be connected to the each light fixture at the back of the trailer.  I just spliced into the white wire at the plug and then ran two wires down both sides of the trailer, then connected to the nuts that hold the lights onto the trailer.
 

Once I did that, they worked! Hope this helps!

[jeff osborne]

I bought my Denali in December and it's been in service about 70 days. Service manager called me Friday to say it's fixed. I went to pick it up and he said not fixed because nothing wrong. They had it a month and did nothing at all. I plugged in a trailer light tester and showed him that non of the lights were working. He said, so what. Because of the virus,  engineering said it's a non issue and not fixable. Wtf? Now my 5 month old truck with 1500 miles on it is home and still cannot pull a trailer because there are no lights. Thanks GMC for the greasy$70k truck

[goosehunter]

3 hours ago, jeff osborne said:

I bought my Denali in December and it's been in service about 70 days. Service manager called me Friday to say it's fixed. I went to pick it up and he said not fixed because nothing wrong. They had it a month and did nothing at all. I plugged in a trailer light tester and showed him that non of the lights were working. He said, so what. Because of the virus,  engineering said it's a non issue and not fixable. Wtf? Now my 5 month old truck with 1500 miles on it is home and still cannot pull a trailer because there are no lights. Thanks GMC for the greasy$70k truck

 Jeff please try this,  connect truck with lights on (parks) and let hooked up for five minutes.....it seems like it takes a  minute for the truck to recognize trailer.....mine was the same way and now everthing is great! It even blinks trailer lights( 1 flash per +- 45seconds) because of theft feature.....nothing to lose!

[davester]

Sounds like you need to find another dealer, or maybe escalate the problem to gm?

[jeff osborne]

I escalated this to gm in February. They began the buy back process but because the idiot service manager told them that nothing was wrong, it was closed. Now I've escalated again and filed for lemon law protection. 

I keep getting errors and 'off' notifications on the dash. Things like Lane keeping off, parking aid off, cross traffic off and others. They are totally random. Sometimes 40 minutes until the first warning and sometimes 40 seconds until the first warning.The warning usually goes away after a minute or so. Who knows how many safety systems are offline. $70k truck and I can't even hook up a trailer or trust the safety systems.

Did I mention that the truck was damaged and repaired {new front fender} before I bought it and this was never disclosed! What a dealership.