'90 K5 - Project Betty - LS3 Swap for a DD/Offroad/Utility Build

[cliles]

Wiring Harness

Following Y5MGISI's suggestion I have located a couple of wiring diagrams and it looks to me like all I need to keep is below. If you know of any more I should keep or if you can answer the maybes then please speak up.

A1 - Fuel Pump Relay
A6 - Power in (this is a maybe)
A8 - Diag Enable in
A9 - Diag Input
A12 - Ground
B1 - Battery
B2 - Fuel Pump Input
B3 - Fuel Pump Ground
B8 - A/C on
B10 - Park/Neut Input (thinking probably no, but didnt want to clip just yet)
C7 - High Gear Input (thinking probably no, but didnt want to clip just yet)
C9 - Crank Input to Starter
C16 - Battery (this is a maybe)
D1 - Ground (this is a maybe)
D2 - Sens return (this is a maybe)

 

[y5mgisi]

I'll check back in in the morning and see if i can recollect anything from my doings.

 

[cliles]

Wiring Delete

Well this is what I started off with. I cut some yesterday, hopefully can finish up today.

 

[Chevy305]

Take your time with the wiring and get it right and get it neat, a pet peeve of mine is messy wiring.

 

[Teck]

It's not that bad to do to make it clean and right. Plug in everything you need and then start pulling out what you don't hook up.

 

[cliles]

So I trying to order some wire loom/sleeve/braid etc. What is a realistic expectation of lengths and sizes needed?

 

[Chevy305]

Order 10ft of each size

 

[cliles]

From 1/8th to 1/2"?

 

[Teck]

You will need a few of bigger then that for your computer connection. I used a painless power braid kit and still had to get more. They have an LS swap kit you can order or look and see what sizes and lengths come in it to get an idea of what you will need

 

[Teck]

IF you would like to come see how I did mine just send me a pm. You are more then welcome to come to Arlington and see it.

 

[Chevy305]

From 1/8th to 1/2"?

1/4" to 3/4" should cover all your bases.

 

[y5mgisi]

Ditto. I did have to use piece of original stuff that was like 1-1/4" or something like that where my harness goes through the firewall. But yea, i would say 10ft of 1/4 - 1".

 

[45acpJr]

From 1/8th to 1/2"?

I recommend some 3/4" also depending on how much of the wiring you are doing. When I re-did my wiring I used an 1/8" larger than needed, I found that no matter how much I planned in advance I still ended up needing to route another wire or two thru. Oh and if you are interested Fastenal carries a good retaining clip for split tubing
http://www.fastenal.com/web/products/detail.ex?sku=11238981

 

[cliles]

Ok, I took a look at my wiring harness (been avoiding taking it out of the box as to not loose anything), and it comes completely wrapped with every plug labelled.

After taking a brief look at it, I wonder if I need any of my old harness. I mean if all I am keeping is AC crap and battery hook ups, the new PCM should have all of that. Right?

 

[Teck]

You will be able to remove some of the old wiring but if you want any of the original gauges and ac to work you cant just go removing it all.

 

[y5mgisi]

Exactly. THe harness you got with the motor will run the motor with no other wires from your truck involved. The wires from your truck that you need to "intigrate" (or at least hide nicely within) the wire harness are things like the oil pressure guage, water temp guage, original fuel pump wiring, starter actuator wire, a ground or two, etc.

 

[Teck]

Here is the sheet from the power braid I used.
Really need more 1/2" then came in the kit. (20 or 30')

Hope that helps.

 

[cliles]

How does the oil pressure and water temp come into play on the old harness?

 

[Teck]

You will need to add the old style sending units to your motor to make them work. You will need to drill and tap for them. Here is where I add them to my motor.



Some of the old style water pumps have a flat round spot on the front that is a good place also.

 

[cliles]

Thanks for the very detailed pics Teck. Also your build is the sweetest I have ever seen. Not sure if I will add those sensors or not. I am looking to go to aftermarket gauges.