New guy with a ton of general questions...

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skipdup

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Spring Branch, TX
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Skip
Truck Year
1990
Truck Model
Suburban Silverado V2500
Engine Size
5.7
Hey guys. Hoping someone can offer some advice and counsel. Brand new to square bodies. Kinda know a little bit about wiring. But also kind of an idiot when it comes to mechanics in general. I've tinkered with new vehicles and vintage race cars for decades. But there are huge gaps in my knowledge compared to most you guys. I also tend to over-think and over-complicate stuff. Part of the rationale in buying this truck was educational-- I plan (hope) to learn all the stuff I wish knew. :)

The truck looks/seems remarkably original(ish) and in good/great shape. I can't find anything that doesn't work how it's supposed to (as far as I can tell). So far, it seems all the wiring is in good shape and hasn't been messed with much at all. But everything electrical seems slow and dim.

I have a growing list of things I want to do. But I think the first things are trailer lights & brake controller (asap), find and clean grounds (& do Big3), headlight relays, and backup lights (with auto/off/on switch) to get started. Also thinking about adding an additional fuse box or two (maybe engine compartment & inside cab?) for future use. In the past, I've always tried to leave factory wiring alone and add my own circuits on top - tapping into existing wires only when completely necessary (i.e. signals to trigger relays).

My biggest source of angst is how to best pass multiple wires in and out of the engine bay to the interior, without it looking like a complete rats nest/hack job. And having room to run additional wires in the future. I don't want to sneak a wire, then another, then another (if that makes sense).

Sorry for there length. And appreciate any advice on this or anything else in general...

Best,
Skip
 

RaisedK5

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First, figure out all the things you might want to add to the truck electrical wise to figure out how many circuits you'll need, then double it. I started out many years ago adding a pair of lights, then another pair of lights, then a cb (shows my age) then a backup lamp, then..........

Then I tore all that crap wiring I did out and started over. Because multiple wires running through the firewall and four or five individual relays screwed to the fender were a disaster waiting to happen.

So then I went to the junkyard ( this was early 2000s) and sourced a fuseblock and a whole bunch of weather pack relays and the mounting rails from some 90 something oldsmobuick and built a standalone wiring system for all my non stock items. Bought every color of wire delcity had and used every circuit in the block and every relay I had whether I needed it or not. Probably had 4-5 that I needed at the time. But now 20 years later. Pretty sure they're all used. Lights, battery isolater, York compressor, etc. At least 9-10 now.

Doing it this way I was able to pull all the trigger circuits through the firewall in one shot all nicely loomed and neat and tidy with a grommet.

Of course I pulled power directly from the battery so it's completely stand alone from the stock electrical system so I don't fry any 48 year old wiring.

Plan it out, leave some expansion room and don't cheap out on the components.
 

skipdup

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Suburban Silverado V2500
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I did not know such a thing existed. That might be perfect. Thank yoU!
 

skipdup

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On the trailer wiring...
Previous owner removed the hitch and trailer wiring. window sticker shows "3-SPEED AUTOMATIC TRANSMISSION HEAVY DUTY TRAILERING SPECIAL EQUIPMENT" and I have RPO code
UY7--TRAILER WIRING,7 WIRE,2 LEAD FRONT HARNESS,5 LEAD REAR HARNESS 7 WIRE TRLR HARN

Anyone know where the trailer wiring harness is located? Would be nice to re-do what the factory did instead of hacking into the tail lights...

Thanks,
Skip
 

Camar068

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I believe there is a "T" harness that you can buy at regular hardware stores. You disconnect the wiring behind the rear bumper, then plug both of those connectors into the "T" harness and done. You may have to convert the output of that "T" to something else depending on what connector your trailer has.
 

Bextreme04

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The two wires to the front will be a 10 gauge orange wire for the 30 amp switched ignition power and a 10AWG blue wire for the trailer brake power. 5 wires to the rear are the T-connector that camaro is talking about and will tie into your rear light harness to provide the stop light, running light, left turn, right turn, and ground wires. That accounts for all 7 wires in a 7-pin connector. If the PO wasn't a complete F-in idiot, you should have those two wires cut and taped onto the harness right under your power brake booster. The other end of that harness is usually just a cut and electrical taped bundle of wires under the rear bumper, since it is usually more work to remove it than it is to just cut it off at the back. You would usually just wire up the trailer brake controller up front with 4 wires; 12v ignition, ground, brake switch, brake power out(this goes to the blue brake line to the 7-pin).
 

skipdup

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5.7
Thanks guys. Really appreciate you guys taking the time.
Hoping next week (or this weekend) I can take a better look and see what's there and what's not.
Thanks again!!
 

75gmck25

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My camper wiring harness is a separate wire bundle (brake and turn signal wires, and ground) that runs from the engine compartment down along the drivers side frame rail to a point under the bed. At that point it would have been connected to the camper wiring. I assume that trailer wiring would also have a similar set of wires running all the way to the back bumper.
 

SquareRoot

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First, figure out all the things you might want to add to the truck electrical wise to figure out how many circuits you'll need, then double it. I started out many years ago adding a pair of lights, then another pair of lights, then a cb (shows my age) then a backup lamp, then..........

Then I tore all that crap wiring I did out and started over. Because multiple wires running through the firewall and four or five individual relays screwed to the fender were a disaster waiting to happen.

So then I went to the junkyard ( this was early 2000s) and sourced a fuseblock and a whole bunch of weather pack relays and the mounting rails from some 90 something oldsmobuick and built a standalone wiring system for all my non stock items. Bought every color of wire delcity had and used every circuit in the block and every relay I had whether I needed it or not. Probably had 4-5 that I needed at the time. But now 20 years later. Pretty sure they're all used. Lights, battery isolater, York compressor, etc. At least 9-10 now.

Doing it this way I was able to pull all the trigger circuits through the firewall in one shot all nicely loomed and neat and tidy with a grommet.

Of course I pulled power directly from the battery so it's completely stand alone from the stock electrical system so I don't fry any 48 year old wiring.

Plan it out, leave some expansion room and don't cheap out on the components.
^^^^^ This some good advice right here! Great job.
 

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