aftermarket wiring harness

[kglowacky]

doing a LS swap on my 78 c10. Need some thoughts on a complete aftermarket wiring harness. I need everything Fuse box a/c etc to install with my swap. Has anyone purchased a harness you are happy with? I will need it to be able to run AC and PW from my oem systems looking for a installation that covers all the headlights taillights and interior gauges etc. Does anyone even make a complete kit like this. Thanks

[LS short box]

For a chassis harness I've used a number of Painless universal kits over the years. American Auto Wire gets good reviews also.
For an engine/trans harness I've used Spear Tech and Howell Fuel injection. Both with good success. Howell is a little cheaper. I buy the computer and the harness from the same company so if there is an issue I have one place to call.

[mongocanfly]

for the truck side harness.i have American autowire...very good kit
for the engine side Ive used PSI ..I want to try BP engine harness on my next one..ive heard the main wiring is longer and would allow the ECM to be mounted under the seat

[kglowacky]

does American give me all the wiring for the dash cluster and gauges, tail lights, door jams, dome lights etc? Does their new fuse box fit in the firewall hole where the factory one did? all wiring except the engine harness??

[LS short box]

I don't know about American but the Painless fuse block would not fit in the stock firewall hole do to the larger number of fused connections. I suspect American would be the same. Both companies include wires and fuses for all basic stuff like lights, turn signals and such. Also both include wires for AC, power windows and radios.
The dash wiring the kits supply are fused wires for the gauges but not the sensors.

[sprint_9]

American Auto Wire needs a larger hole in the firewall as well.

I used the AAW chassis harness and was pretty happy with it. I used a BP engine harness but probably wouldn't again, I haven't been happy with it overall. I'd use a Speartech if I did it all over.

[derotoreut]

I would use the American Autowire Classic Update. It's no big deal to enlarge the hole. You have to remove the old fuse box anyway. They give you a pattern to use. I've used both AAW and Painless. I prefer the AAW. IMO Painless is anything but painless.

[nsb29]

I used aaw classic up grade nice kit, but doesn’t come with grommets you have to bye them separately. Don’t understand about enlarging any holes because it uses all original grommets! But you will have to You integrate the to together. I used bp automotive and liked it and it is long enough to go under the seat

[LS short box]

I don't know what level of project you are doing but on my project I filled the original fuse block hole and then moved the Painless fuse block back a bit from the firewall using a "L" bracket I fabbed. Then I ran all the chassis wiring over the top of the steering column and then made hole it trans tunnel for the wires. Ran the wires forward and back as needed. On my truck you can't any of the chassis wires.

[kglowacky]

has anyone used the painless harness 10201 or #10206. Just talked with painless they are trying to sell me the 10206 and say the 10201 would work. the 01 I think a universal harness and really have no reason to think it cant work. Neither has the gauge cluster plug so I would need to use my old one LOL I don't have an old one. Please let me know if anyone can shead some light on this. Thanks

[skyphix]

I can't comment on the chassis harness yet - when it comes time I'll be doing a very stripped out chassis harness (not running the factory dash, eliminating a bunch of unneeded wiring for my stripped out truck) so I plan on using the AAW universal wiring kit.

For my engine harness and PCM, I used PSI. Their support and the quality of their product, in my experience, has been top notch. Truck runs awesome and besides the MAF wiring being too short (I used the factory intake tract... if you used an aftermarket and kept the battery on the passenger side, it would be perfect) which they told me it would be, I didn't have to do anything. I just grabbed an extension for the MAF so I didnt have to cut the harness. I'll be ordering their universal truck pedal soon as well.

[LS short box]

I've used the 21 circuit universal Painless on a number projects. Most were LS swapped projects. I saved all the connectors off the original car/truck harness and the mated them to the Painless harness as needed. Get a wiring diagram for the original truck harness. These trucks are pretty simple. I think the direct Painless harness is configured to plug right in the truck components.

[MDPotter]

American Autowire classic update is my preferred route. I don't know of a harness that includes the complete chassis, LS, and fuel pump/fans. Autowire Has extra circuits for modern upgrades like power seats, power locks, etc. or you can use them to power your LS harness and clean things up. Either rework your LS harness yourself or have Speartech do it. Run a separate fuse/relay block for fuel pump and fans.

[kglowacky]

I have had my harness reworked and agree with you 100% on running separate systems. My questions are on what have people used. Painless sells a lot of different ones but I cant really see a lot of difference for the 300$ difference they are asking.

[Scott2]

For the vehicle wiring, I used Affordable Street Rods - great kit, awesome instructions!

For the engine, From my own experience I would say whatever you do don’t use LS1Swap Garage. My harness went in a black hole and had a heck of a time getting it back. When I did it was not done right. Sent it back and same fight to get it back. My one serious requirement was to leave the emissions connectors - and they’re gone!? He won’t respond to my messages. Guy’s a nightmare and I have to go buy a new harness.

[truckdude239]

I used the American auto wire classic update kit on my 71 I hate wiring but would use the aaw kit again in a heart beat and had the stock harness for ls engine modified

[ewoody625]

I did painless and had my stock harness modified for my 70. I don't think the painless kit was that bad but I have no experience with any other harnesses.

[68isgreat]

TTT.

I just completed a 350 TBI conversion on my 68 using a Painless harness for the engine side. For the chassis harness, wouldn't it be pretty easy to use one of the universal harnesses for $100 and graft the wires in from my original harness? Even if I spend $500 for another Painless or AAW harness, I'll still have to adapt it, so I'm not sure what the extra $400 gets me? Just curious what you guys are doing nowadays with modern drivetrains and your chassis harnesses. Thanks.

[biketopia]

Originally Posted by 68isgreat

TTT.

I just completed a 350 TBI conversion on my 68 using a Painless harness for the engine side. For the chassis harness, wouldn't it be pretty easy to use one of the universal harnesses for $100 and graft the wires in from my original harness? Even if I spend $500 for another Painless or AAW harness, I'll still have to adapt it, so I'm not sure what the extra $400 gets me? Just curious what you guys are doing nowadays with modern drivetrains and your chassis harnesses. Thanks.

Holy 4 year old thread bump. If you wanted to "graft" new wires into your old harness then yes I suppose a universal harness and fuse box would work. But why go through the trouble introducing new splices and using 50+ year old wiring and connectors? The idea of putting a whole new chassis harness in is to have your chassis wiring as modern and updated as your drivetrain harness. If you're happy with how your chassis harness is performing then just leave it alone.

[itsmike2k]

So since this Thread has already been bumped . Im getting started on my 72 C10 LT1 Gen V Swap.. Just picked up a 23 LT1 w/ 10L80. I originally I had a 96 Lt1 with a 4l60E in this truck and had it running good. I cut and splice on the factor C10 harness and the 96 wiring and ecm myself. But tore it down in 2007 to bag it, paint the frame and its been sitting ever since..

So 17+ years later going to start back up .. Anyway looking at a painless 10206 Chassis Harness and from there I'm not certain yet.. I have purchased a bunch of parts for the build.. Wilwood Big Brake Front and rear discs brakes, Aluminum Radiator, new front belt kit with PS pump, and new rear fuel cell.. I have the intact factory LT1 harness/ECM/TCM thinking maybe Swaptime to have the harness modded for my truck.. Anyone have any experience with them or any other suggestions? Thanks!!

[87chevy.com]

Lt1 swap is not much different than LS swap. I offer a connector kit for gen5 swaps on ebay.

https://www.ebay.com/itm/322431112275

[itsmike2k]

thanks ill check it out!!