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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => LS Swaps => Topic started by: Low82C10 on July 04, 2012, 10:21:13 PM

Title: another wiring question looking for VileZambonie
Post by: Low82C10 on July 04, 2012, 10:21:13 PM
Reason im asking for vilezambonie is i seen a post he helped out a lot about this topic. mine is a different as im doing a LS swap. My motor is ready to drop in the harness is ready to go, its a three wire hook up harness, which only needs 1) Constant 12 Volts.....2) Switched 12 Volts..Hot in RUN and START....3) Fuel pump 12 Volts. That being said, i started cleaning my engine bay tracing wires i willno longer need, alternator wire, etc. well here is my question about the junction box, what will feed my truck since these are the wires i had before.

The two top ones on this picture went to the bulkhead connector then clockwise it went alternator, starter, junction box.
(http://farm9.staticflickr.com/8431/7505298284_9abee01a69.jpg)

This set went from the junction box, alternator and the middle connection went to the bulkhead connector.
(http://farm9.staticflickr.com/8015/7505299854_612e7db887.jpg)

I know i heard you guys say its good to have the fusible links. are these them?
(http://farm9.staticflickr.com/8023/7505296974_6d08b442af.jpg)

what im trying to get at is, i want my engine bay to look as clean as possible with out so much unneeded wires, do i need to keep these wires around if i only need what i mentioned up top?
and do i have to keep some sort of fusible link? and last im assuming the truck go power from when the battery would connect to the starter and the starter had a wire going to the junction box, so that being how the truck got its power for lights etc when truck wasn't running, so i still would need something going from starter to box right?
Title: Re: another wiring question looking for VileZambonie
Post by: Captkaos on July 07, 2012, 10:56:47 PM
You are going to need a power distribution set of wires, and you are going to have to have wiring going to the alternator and the starter from the inside of the truck.  The LS harness won't generally have the starter and all the alternator wiring, so you need to keep what you can, and you defintiely want to keep the fusible link, unless you want to burn up all the wiring...

I should be starting on the underhood wiring on my LS conversion tomorrow.  The LS should need constant power, switch power, GROUND and Fuel pump and if you are using a Auto Tranny you need a brake switch.

Whose harness are you using?
Title: Re: another wiring question looking for VileZambonie
Post by: Low82C10 on July 10, 2012, 12:23:04 AM
the LS harness i have does have a wire going from the alt to the starter, what wiring will need to go to inside the cab, isnt there already wires that go inside at the bulk connector from the starter/alt?? Dave with foxlanders in arizona did the harness im picking the motor/harness up tomorrow.
Title: Re: another wiring question looking for VileZambonie
Post by: Captkaos on July 11, 2012, 03:36:50 PM
I meant separate wiring from the cab to the starter and also to the alternator. you need it from the truck.
Title: Re: another wiring question looking for VileZambonie
Post by: Low82C10 on July 14, 2012, 03:55:59 PM
so i can just connect my same wires that went to the alt and starter to the new alt and starter, well maybe just the starter since there already is a wire to starter from alt
Title: Re: another wiring question looking for VileZambonie
Post by: Captkaos on July 16, 2012, 11:07:28 PM
I don't know what harness you are using but if you are using a 99+ ECM it will need a wire coming from the ECM to the B terminal on the Alternator.  The normal 12V wire will go to the C terminal and provide 12V when the switch is in the run position and you will run the battery to the post on the side.

What year model Alternator are you using?  Donor engine year?  And PCM number?

It could be as simple as using one of these adapters (depending on if you are running a warning light or not).  Most 99+ don't need the resistors..
http://www.qualitydist.net/pico-5327pt.html (http://www.qualitydist.net/pico-5327pt.html)
http://www.qualitydist.net/pico-5328pt.html (http://www.qualitydist.net/pico-5328pt.html)




Just found this via google:
http://www.ls1tech.com/forums/conversions-hybrids/779728-thee-alternator-faq-thread.html (http://www.ls1tech.com/forums/conversions-hybrids/779728-thee-alternator-faq-thread.html)