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Trailer 7 Pin Recepticle Problem

jmp2204

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jmp2204 Enthusiast

jmp2204

Posted
Posted

have an 04 chev truck with a factory trailer harness (7 pin) i have flashers(signal/4 ways) but no brake light getting to the recepticle(on the truck)wondering if there is any known issues that are common on these?where does the brake light join the flashing lights in the circut? all the lights on the truck work fine. thanks

95Sierra2500 Senior Enthusiast

95Sierra2500

Posted
Posted

When you step on the brakes and light up the brake lights, the same circuits that carry the flashers should also carry the brake lights. At least that's how it's been on every trailer I've ever pulled.

 

If you're not getting power to the electric brakes on your trailer, that's a different story. You need a brake controller installed to get that.

jmp2204 Enthusiast

jmp2204

Posted
  • Author
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When you step on the brakes and light up the brake lights, the same circuits that carry the flashers should also carry the brake lights. At least that's how it's been on every trailer I've ever pulled.

 

If you're not getting power to the electric brakes on your trailer, that's a different story. You need a brake controller installed to get that.

yes flashers are working on the recepticle but not the brake lights
Draenor Senior Enthusiast

Draenor

Posted
Posted

One of two things..Incorrect wiring on the trailer or a grounding problem. I would lean towards a grounding problem, since your signal lights are working. As Tim stated, these are the same lights as the brake lights on the trailer.

 

Check that the plug is seating correctly and is free of corossion or debris on the pins. Next check the grounds. There is usually on up front and one for each tail light.

 

Are you using the full 7pin or a conversion from a 7 to flat 4 pin adapter? Is this a boat trailer by any chance?

jmp2204 Enthusiast

jmp2204

Posted
  • Author
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One of two things..Incorrect wiring on the trailer or a grounding problem. I would lean towards a grounding problem, since your signal lights are working. As Tim stated, these are the same lights as the brake lights on the trailer.

 

Check that the plug is seating correctly and is free of corossion or debris on the pins. Next check the grounds. There is usually on up front and one for each tail light.

 

Are you using the full 7pin or a conversion from a 7 to flat 4 pin adapter? Is this a boat trailer by any chance?

.trailer is good(sled trailer).the wires going into the back of the truck recepticle is where i am testing them(so before the truck recepticlein the harness).signal lights are working fine going to the recepticle but not the brake lights and yes i am aware they are on the same circut ( and every light on the truck works fine)yes i am using a 7-4 adapter(but no power is getting to the 7 on the truck for the brake lights) i know there is a fuse for the left brake/ flasher and a fuse for the right brake /flasher ,but i have been told there is also another fuse for the trailer brake light only under the hood(doesn't make sense that there would be) but i look tonight...Thanks for your input guys!!! i'll also check for ground issues
c4cruiser Enthusiast

c4cruiser

Posted
Posted

There is a second fuse panel in the driver's door jamb at the dash Pull that cover off and you may find the trailer lighting fuses there.

 

Having separate fuses for the trailer harness and the truck's rear lamps keeps the circuits separate so that you will still have truck lights even if something goes bad in the wiring harness back to the trailer connector.

jmp2204 Enthusiast

jmp2204

Posted
  • Author
Posted
There is a second fuse panel in the driver's door jamb at the dash Pull that cover off and you may find the trailer lighting fuses there.

 

Having separate fuses for the trailer harness and the truck's rear lamps keeps the circuits separate so that you will still have truck lights even if something goes bad in the wiring harness back to the trailer connector.

i think you may have misunderstood me,fuses dedicated to the trailer harness are good,i know they are there ,someone told me that in addition to the trailer harness fuses (in the cab) for the leftf/brake, rightf/ brake there is an additional fuse for the trailer brake light only under the hood. that makes no sense but i'll check tommorrow(i just got home from work and it's 11:37 pm (i started work at 7:30 am )thanks for your input
  • 1 month later...
FOG New Member

FOG

Posted
Posted
have an 04 chev truck with a factory trailer harness (7 pin) i have flashers(signal/4 ways) but no brake light getting to the recepticle(on the truck)wondering if there is any known issues that are common on these?where does the brake light join the flashing lights in the circut? all the lights on the truck work fine. thanks

 

Found this site trying to determine why MY trailer stop lights were not working...no voltage at 7-pin when brake applied. Well, I remembered that my hazard switch didn't work either. Long story short...a bad hazard switch in the turn signal assembly was keeping my trailer brake lights from working. All other lights worked fine with bad switch. And I'd really like to have a 'talk' with the engineer that designed the two-wire plug with the keeper key on the shift linkage. Hemostats only way to get that back in.

 

Hope this helps those that find this thread.

 

Later,

Alex

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