Custom reroute for reworked harness
 

Any one have any pics of work they did to customize the harness, minimize it to tuck and hide wires?

I am working with a dirty reworked 5.3 DBC, NON FLEX-FUEL harness. It has transmission wires still in it and want them gone so I want to redo it, clean it, and maybe reroute wires to shorter paths. Just looking for tips and advice as I start the tear apart of loom.

Re: Custom reroute for reworked harness
 

I don't have any pics or advise yet. I haven't started modifying mine. Just keep in mind that your two statements above are likely impossible together. A hidden harness will be significantly longer. A shorter harness will be more visually intrusive.

Re: Custom reroute for reworked harness
 

I meant minimizing it in regards to elimimating wires not needed. I'm not so concerned with length...pcm will go inside cab. I think with all wires undone from loom and routing them in shortest paths will allow pcm connections to go inside cab without having to extend anything. Just wanted to see if anyone had done this with success.

One question i had is do guys need temp. Sensor plug to not turn on eng. Light?

Re: Custom reroute for reworked harness
 

Yes you will need the temp sensor or it won't run correct. Its very important.
Dave

Re: Custom reroute for reworked harness
 

If you want the PCM inside the cab, you'll have to lengthen a lot of wires in the truck harness (a car harness works a lot better from the standpoint of minimal mods to put the PCM inside).

I've reworked the harnesses on 2 C10s with the PCM inside the cab and 6 with the PCM in the engine bay.

Yes, you need the temp sender. You can eliminate the rear o2 sensors, the oil pressure sensor, the evap connections, the AC pressure senders and, in your case, the trans wiring. In the grand scheme of things, that's not a lot. The harness is pretty much "standalone" already.

Good luck with your project.

Re: Custom reroute for reworked harness
 

Can you verify if i have wires i need?
Running a th350
8 - injectors
2 - coil connector
2 - oxygen sensors
1 - maf
1 - map
1 - alternator
1 - idle air control
1 - tps
1 - crank. Pos. Sensor
1 - Cam pos. Sensor
1 - knock sensors
1 - temp. Sensor
3 - ground terminals

Re: Custom reroute for reworked harness
 

You need all those, but, off the top of my head, you're missing 1 knock sensor (there are 2 total), the cam sensor wiring, and the fuel pump control.

Depending on what you do for gauges and fans, you may want something for those as well.

Re: Custom reroute for reworked harness
 

Agreed...2 knock sensors but 1 plug for both of them...but big thank you. I almost forgot about cam sensor.

Re: Custom reroute for reworked harness
 

If you are planning on reworking your own harness, lt1swap.com is an immensely helpful resource.

As for mounting in the cab, the blue/red harnesses are significantly shorter than the blue/green ones. Though I have mounted the pcm in the cab of a 56 truck using a blue/red harness and only needed to lengthen a couple of wires, but it was tight. Though I do completely depin the PCm connectors and customize the routing of all the wires. Makes for a very clean harness.

Re: Custom reroute for reworked harness
 

When shortening wires, I assume you all are shortening the PCM end? I've figured out how to depin the PCM connector(google "mx123 molex connector manual," and look for a sizable PDF), but I'm not sure what comes next. What crimping tool, and what "bullet" ends are you using on the wires? Any google search terms or links would be appreciated. This will likely be a one-time project, so I don't want to get very spendy with crimping tools.

Re: Custom reroute for reworked harness
 

I have been looking at lt1swap some...along with videos from Rowdy...swap into a jeep. By far best video of how to do a harness. I took my already reworked harness completely apart and ready to eliminate wires not needed that the place I got it from didn't. Next step is place harness clips in place and wire tie the wires to my liking. Hopefully that leaves me enough slack to put PCM in cab. If not, I should be able to put it a safe place in engine bay.

Re: Custom reroute for reworked harness
 

X2 on UCANDOIT2 (Rowdy) from youtube. He almost had me convinced I could rework my own harness...ALMOST.

Re: Custom reroute for reworked harness
 

Mine was already done...but pretty poorly. They left cut wired in the greasy destroyed loom that was left...along with trans. wires. I think for next swap...I may do it all myself....MAYBE. :)

Re: Custom reroute for reworked harness
 

While you still need the temp sensor, you can move it to the back of the engine on the other bank where it is a lot less conspicuous.

Getting the ECM inside the cab helped a lot, but the coil packs are damned ugly. I shaved them and bought harness extensions so I could either put the coil packs on the inside of the firewall in the cab, or down on the frame rails. Here's a shot of the shaved valve covers painted in a wrinkle black finish-

https://talk.classicparts.com/media/...-lm4.4118/full

Getting rid of that gawd-awful black conduit and electrical tape is the next order of business. For everything I can't tuck or hide that can be seen when you open the hood, I'll de-pin the connectors and cover the wires with black Techflex, with the last inch or so to the connector covered with heat shrink - no tape allowed! Buy several sizes for a tight fit. I'll also heat shrink at every 'branch' of the harness to clean it up some. You can buy literally 100s of pieces of heat shrink in a kit off ebay for about $10.

If you're using any kind of crimp connector (other than the Packard crimper for connector pins) - Stop. Learn how to do a 'western union' or lineman's splice and solder and heat shrink all connections.

All the wiring from the front of the engine will run under the intake manifold to the back of the motor and on to the ECM

For other parts of the harness that will be out of view, I bought a product called "Roundit 2000" made by Federal Mogul. It looks like a mesh covering but is actually split down the middle to allows you to get at the harness if needed.

Well, that's my plan anyway.............

Re: Custom reroute for reworked harness
 

Great ideas...and impressive!! If I end up keeping this truck...I will definitely do this.

Re: Custom reroute for reworked harness
 

I will have to disagree about the western union splice, thats a great connection if you are doing it properly but for something that sees as much vibration as an engine harness you really need to imobilize it with rigid adhesive heatshrink to prevent the solder from cracking over time.

A good quality uninsulated butt connector crimped using a good set of ratcheting crimpers makes for a better splice than 90% of people can make with a soldering iron. Just cover with some flexible adhesive lined heatshrink for weather protection and be done.

Re: Custom reroute for reworked harness
 

I also wondered about soldering and it cracking with stress. I am going to use butt connector with heat shrink tubing. I'll post pics once I'm done...waiting on a couple pigtails.

Re: Custom reroute for reworked harness
 

"A good quality uninsulated butt connector crimped using a good set of ratcheting crimpers makes for a better splice"

Couldn't agree more.

The problem is that many don't use 'good quality' butt connectors and ratcheting crimpers and will use a Chinese splice kit bought at Autozone. Worse yet is two wires twisted together and wrapped with electrical tape. (or a wire nut from Home Depot)

Most guys have a soldering iron though, and with a little care can do a decent splice.

I'm about to do a chassis wiring harness on my truck and still a lot to do on my engine harness - any recommendations for crimper brands. It might be time to step up.

Re: Custom reroute for reworked harness
 

I've done quite a few soldered connections on off-road cars and never had a problem. I've heard of factory chassis and engine harnesses having to be replaced on trucks used in oil fields in Texas due to severe environments and lots of miles. (shops in Arizona do a fair amount of them due to pack rats eating the insulation off of cars parked outside)

But a soldered joint can crack and best practice on any wiring is to make sure it is properly bundled and supported so as not to transmit excess stress or vibration into the wires.

Re: Custom reroute for reworked harness
 

Or just buy a painless bar was with the extended length and be done. Or buy a proper terminals for splicing wires

http://www.te.com/usa-en/product-963...-docs-features

And a open barrel crimper for that type and quality adhesive lined heatshrink.

If you have no experience and confidence in wiring repair, best bet, buy painless. Don't want to be left stranded due to a poor connection, or intermittent connection and even worse it doesn't run once you lengthened it.

Re: Custom reroute for reworked harness
 

Geez....so what do i do now....?
Don't touch any wires without my electrician buddy present? ...he does like to drink his craft beers when we get together....got it!....

Re: Custom reroute for reworked harness
 

I think this should read, ''if you have no experience or confidence.''
What to do now depends on you. I modified the above statement that seems to have given you second thoughts. Nobody was born knowing how to do this kind of thing, it takes practice, and there's no better way to learn to do it than by just doing it. Determine if you think you can do it or not, only you can answer that. Just take your time and double check your work and you should be fine. Do know that anything can happen, but if it does, having done it yourself will give you some knowledge on how it works and therefore more of an ability to fix it. A 'can do' attitude will go a long way. ;)

Re: Custom reroute for reworked harness
 

I don't know what you're going to do, but I think I'll go do that 'painless bar' thing. A couple drinks there should set things right!

Re: Custom reroute for reworked harness
 

Agreed!!

Re: Custom reroute for reworked harness
 

Been there, done that. Plan on spending a lot of time reworking each wire.