Lsx swap with some electrical issues.. Help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

GOODYGOODS · 02-11-2014, 10:33 AM

I have a 79 silverado that i swaped an 04 4.8l into it and i'm having some electrical issues. I used the factory wiring harness from the 04 and modified it per the lt1swap.com website and i just spliced the factory alternator wire to the 4.8 factory alternator. Now my problem is the fusable link wire that goes to the junction on the firewall. Originally i think the wire was a fusible link but somewhere along the lines an inline fuse was put on it and now I keep poping the fuse. It seems to happen mainly when its raining or snowing. Any advice or help would be greatly appreciated.
thanks

Josh

ls1nova71 · 02-11-2014, 12:20 PM

Quote:

Originally Posted by GOODYGOODS

I have a 79 silverado that i swaped an 04 4.8l into it and i'm having some electrical issues. I used the factory wiring harness from the 04 and modified it per the lt1swap.com website and i just spliced the factory alternator wire to the 4.8 factory alternator. Now my problem is the fusable link wire that goes to the junction on the firewall. Originally i think the wire was a fusible link but somewhere along the lines an inline fuse was put on it and now I keep poping the fuse. It seems to happen mainly when its raining or snowing. Any advice or help would be greatly appreciated.
thanks

Josh

You spliced the 4.8 alternator wiring into the '79 wiring? Not to sound like a smart ass, but why? The factory 4.8 harness has the alternator wiring all contained, so you shouldn't have had to do anything to it. The wires go from the alternator straight to the PCM, and PCM will regulate it.

GOODYGOODS · 02-11-2014, 01:58 PM

Na, your good. I know the harness connects to the alt but the connection on the back of the alt for charging the battery. I followed some of the other swaps on here and that was what i thought was the way to wire it.

Andy4639 · 02-11-2014, 05:51 PM

No splicing into the wiring on mine. it's all done in the new wiring.

BR3W CITY · 02-11-2014, 09:19 PM

Which plug did you have, and which wires did you splice...

GOODYGOODS · 02-17-2014, 12:14 PM

I didn't splice any wires for the ls harness. I only spliced a wire to the back of the alternator into the 1979 factory wiring that use to go to the power teminal on the back of the factor 1979 alternator.

ls1nova71 · 02-17-2014, 01:57 PM

Ok, this is making more sense now. So you have the alternator wired like stock, controlled by the PCM, and it's charging correctly? This is what I'm getting, but the wire that powers up the rest of the trucks electrical system/fuse box has a fuse in it that keeps blowing? First off, how do you know what size of fuse to put in it? You say it does it mainly when it's raining or snowing, so have you checked your wiper motor? Maybe it's going out and pulling too many amps? Or could be that with the heater blower on, the headlights on, the wipers on, and the radio on it's just too much for what ever fuse you have powering up the fuse box.

GOODYGOODS · 02-17-2014, 04:08 PM

Yes it is wired like stock, controlled by the pcm, and its charginge correctly (13.3-14.1v). If i am not mistaken all of the other systems work when the fuse blows and the size i am using is the size that was in it when i found it blown. I do not think it should be a inline fuse but a fusable link but there was already an inline fuse there so i replaced it with one. And i thought the same thing about it pulling too much power when everything is on but it only kills the ignition when it blows, everything else works. I hate electrical and was curious if anyone else has had the same issue. I wouldn't think anything getting wet would do it since its in the engine compartment and i would assume that it has always gotten somewhat wet over the years. thanks for the comments

BR3W CITY · 02-18-2014, 02:34 AM

Do you have a radio or added electronic off the keyed 12v? That combined with the ignition draw could pop it if its undersized.

FWIW, mine doesn't use any modern breakers or anything, just normal fuses and relays divided out for the systems. I replaced my whole trucks interior harness with new, and used a universal 12 circuit breakout.

GOODYGOODS · 03-31-2014, 01:09 PM

No added electricals. Does anyone know what size fusible link the wire going from the alt to the starter needs to be?

littlevictories · 03-31-2014, 09:33 PM

i got a section on 12ga fusible on mine.

02-11-2014, 10:33 AM	#1
GOODYGOODS Registered User Join Date: Aug 2012 Location: FOUNTAIN INN, SC Posts: 8	Lsx swap with some electrical issues.. Help! I have a 79 silverado that i swaped an 04 4.8l into it and i'm having some electrical issues. I used the factory wiring harness from the 04 and modified it per the lt1swap.com website and i just spliced the factory alternator wire to the 4.8 factory alternator. Now my problem is the fusable link wire that goes to the junction on the firewall. Originally i think the wire was a fusible link but somewhere along the lines an inline fuse was put on it and now I keep poping the fuse. It seems to happen mainly when its raining or snowing. Any advice or help would be greatly appreciated. thanks Josh

02-11-2014, 01:58 PM	#3
GOODYGOODS Registered User Join Date: Aug 2012 Location: FOUNTAIN INN, SC Posts: 8	Re: Lsx swap with some electrical issues.. Help! Na, your good. I know the harness connects to the alt but the connection on the back of the alt for charging the battery. I followed some of the other swaps on here and that was what i thought was the way to wire it.

02-11-2014, 05:51 PM	#4
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Lsx swap with some electrical issues.. Help! No splicing into the wiring on mine. it's all done in the new wiring. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-11-2014, 09:19 PM	#5
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: Lsx swap with some electrical issues.. Help! Which plug did you have, and which wires did you splice... __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

02-17-2014, 12:14 PM	#6
GOODYGOODS Registered User Join Date: Aug 2012 Location: FOUNTAIN INN, SC Posts: 8	Re: Lsx swap with some electrical issues.. Help! I didn't splice any wires for the ls harness. I only spliced a wire to the back of the alternator into the 1979 factory wiring that use to go to the power teminal on the back of the factor 1979 alternator.

02-17-2014, 01:57 PM	#7
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,118	Re: Lsx swap with some electrical issues.. Help! Ok, this is making more sense now. So you have the alternator wired like stock, controlled by the PCM, and it's charging correctly? This is what I'm getting, but the wire that powers up the rest of the trucks electrical system/fuse box has a fuse in it that keeps blowing? First off, how do you know what size of fuse to put in it? You say it does it mainly when it's raining or snowing, so have you checked your wiper motor? Maybe it's going out and pulling too many amps? Or could be that with the heater blower on, the headlights on, the wipers on, and the radio on it's just too much for what ever fuse you have powering up the fuse box. __________________ My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html

02-17-2014, 04:08 PM	#8
GOODYGOODS Registered User Join Date: Aug 2012 Location: FOUNTAIN INN, SC Posts: 8	Re: Lsx swap with some electrical issues.. Help! Yes it is wired like stock, controlled by the pcm, and its charginge correctly (13.3-14.1v). If i am not mistaken all of the other systems work when the fuse blows and the size i am using is the size that was in it when i found it blown. I do not think it should be a inline fuse but a fusable link but there was already an inline fuse there so i replaced it with one. And i thought the same thing about it pulling too much power when everything is on but it only kills the ignition when it blows, everything else works. I hate electrical and was curious if anyone else has had the same issue. I wouldn't think anything getting wet would do it since its in the engine compartment and i would assume that it has always gotten somewhat wet over the years. thanks for the comments

02-18-2014, 02:34 AM	#9
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: Lsx swap with some electrical issues.. Help! Do you have a radio or added electronic off the keyed 12v? That combined with the ignition draw could pop it if its undersized. FWIW, mine doesn't use any modern breakers or anything, just normal fuses and relays divided out for the systems. I replaced my whole trucks interior harness with new, and used a universal 12 circuit breakout. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

03-31-2014, 01:09 PM	#10
GOODYGOODS Registered User Join Date: Aug 2012 Location: FOUNTAIN INN, SC Posts: 8	Re: Lsx swap with some electrical issues.. Help! No added electricals. Does anyone know what size fusible link the wire going from the alt to the starter needs to be?

03-31-2014, 09:33 PM	#11
littlevictories Registered User Join Date: Dec 2013 Location: Portland, Ore. Posts: 348	Re: Lsx swap with some electrical issues.. Help! i got a section on 12ga fusible on mine.

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