Stock 2-wire connnector above bumper - for trailer brakes?

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Tucano396

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Mostly done fixing the butchered wiring across my [still somewhat new to me] 1994 Suburban.

At some point a 7 pin harness was installed. They spliced into the wires for the truck's 4 pin connector; and then it looks like they made it actually function as a 7 pin by running a loooooooooong wire from the firewall junction block for electric trailer brakes.

My question: I noticed a 2 pin connector (black with blue caps in my photo; I think C403 in the attached shop manual page) near the 4 pin one. What's it for? Was it intended to provide power for electric trailer brakes?

I know there are aftermarket 4 pin solutions that simply plug inline with the truck's 4 pin connector, so it would be awesome if this 2 pin provides a means to easily jump up to 7 pin capability.

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GMCTruck

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I don't think the two wire connector would be for trailer brakes. Wire gauge is too small. To me that looks more like wire for lights, maybe the license plate lights. (??). The pickups usually came with a blunt cut loooooooong blue wire from under the brake booster to the back end of the truck along the drivers side frame. It is a 10 or 12 gauge wire and used for trailer brakes. Not sure about the suburbans.
 

Caman96

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Mostly done fixing the butchered wiring across my [still somewhat new to me] 1994 Suburban.

At some point a 7 pin harness was installed. They spliced into the wires for the truck's 4 pin connector; and then it looks like they made it actually function as a 7 pin by running a loooooooooong wire from the firewall junction block for electric trailer brakes.

My question: I noticed a 2 pin connector (black with blue caps in my photo; I think C403 in the attached shop manual page) near the 4 pin one. What's it for? Was it intended to provide power for electric trailer brakes?

I know there are aftermarket 4 pin solutions that simply plug inline with the truck's 4 pin connector, so it would be awesome if this 2 pin provides a means to easily jump up to 7 pin capability.

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This???
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Tucano396

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I don't think the two wire connector would be for trailer brakes. Wire gauge is too small. To me that looks more like wire for lights, maybe the license plate lights. (??). The pickups usually came with a blunt cut loooooooong blue wire from under the brake booster to the back end of the truck along the drivers side frame. It is a 10 or 12 gauge wire and used for trailer brakes. Not sure about the suburbans.
Good point about the gauge. And thanks for the info, i'll check if such a wire exists in my case (for the quality of work I've been correcting, it wouldnt surprise me if they never noticed it)
 

Tucano396

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This???
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Yup that seems to be it. Shop manual says it's "rear lamp harness to end gate" -- gee, how vague.

A few wiring diagrams in the shop manual show SOME of the wires belonging to C401 and C403 but either the writers didn't care to show the other wires or my Where's Waldo searches thru the wiring diagrams have missed them.

Either way, I believe I've got enough info to know how to proceed.
 

GoToGuy

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You found the connectors and wire numbers in the routing illustration, did you go to the wiring diagram in service manual to identify what it is. It's in Section Eight electrical.
 
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