79 GMC Sierra LWB 6.0L swap

[glock35ipsc]

Get a different fuse block, I wouldn't run that one, Sorry, but they are kinds cheesy. I would get one like this:



Summit sells them for around $7. One of the terminal strips goes in each side. This way, you can cut one terminal off of each strip, and use that as the constant 12v in (at say, the top), then when the fuse is plugged in, it carries power to the opposing strip. There is the constant power source for the one wire.

For the three ignition wires, use the strip the has three terminals on it and run one power wire to it (* more on this wire later) and plug it in the same side that the constant 12v wire is in. One the other side, cut an separate the other three terminals so you have three individuals. The three ignition wires from the harness will go there. (Run short pig tails to the terminals before plugging them in to the block, THEN connect the harness wires to the pigtails.)

* For the ignition-on wire, use a relay for this. I ran a large gauge wire from the alternator to my fuseblock. I split it at the fuse block.... one to the 12v constant, one to the relay.

I'll find some pics to post up for you. I think I even drew a diagram somewhere. I'll be back in a bit.

[glock35ipsc]

Here you go. If I remember right, I have a 20A in the constant, and 10A in the ignition spots.

I wish I had more of these fuse blocks, I would set a few up for you guys. I got these off of old harnesses we used when I did van conversions. But I am being stingy with them. I anyone wants to send me a fuse block like these, I would be happy to set them up and send them back to you.

BTW, in the bottom pic, I don't have the fuses plugged in yet. The relay on the right side is for the ignition-on wires. The one below the fuse block is for the fuel pump.

[buckshot305]

I knew Bob would come through for you! I like his method much better than what I had in my head. The diagram makes perfect sense too. I'll be sure to bookmark this page.

[79gmc5.3]

Originally Posted by buckshot305

I knew Bob would come through for you! I like his method much better than what I had in my head. The diagram makes perfect sense too. I'll be sure to bookmark this page.

Thanks Bob I still have your diagram that's why I was confused with the fuse block I have. Ordered one like yours from Summit it's a Painless so it should be good, will be here today. Very fast shipping. Will try to get that done tonight after work. I really want to start this thing! Hey buckshot that beer is ICE cold! Come on by!

[glock35ipsc]

Excellent! Those connectors take a special crimper. You don't have to buy one, you could use some needle nose pliers to bend the tabs over though, but definitely solder them! I do have the crimper for them, but I still solder them always. The crimper runs about $35 from Mac Tools, but I would bet you can find them cheaper somewhere. They are called an "open barrel crimp tool" or "open barrel contact crimp tool". I've had mine since the early 90's.

[nlped]

^^^Another fancy tool....Show Off

[79gmc5.3]

Again thanks Bob, I think I have one of these but not sure and I will solder the connectors.

[Rav3n]

Great progress and love your truck, man! This is my inspiration for my next project cuz I've always wanted one with the color scheme ya chose!

[79gmc5.3]

Originally Posted by Rav3n

Great progress and love your truck, man! This is my inspiration for my next project cuz I've always wanted one with the color scheme ya chose!

Thanks man. I took the good advise of my wife when I chose the color scheme. I tried to pick colors from a book and she made the suggestion to go to car lots and see it in natural light and on a large surface, and when she saw a 2008 GMC Seirra with those colors she said that's it! So I have to give her all the credit for that and I love it also.

[79gmc5.3]

Ok guys I am knee deep into this wiring! I think with the wiring diagram from Bob and others on this forum I think I have the new harness figured out. My question is the old wiring from the starter and the alt, do I need to use these for my 12v switched and full time 12v leads to the fuse block or cut and block them off. I have 2 wires that go from the fuse block plug on the firewall to the starter and solenoid should I use these? If any of you have a wiring diagram of the old wiring that I could use I would appreciate it. Thanks in advance

[glock35ipsc]

Here is what I did.....

In the W4M harness, there should be a purple wire tagged "starter", it's original to the GenIII harness and runs to the starter solenoid. I took the purple wire (original to the truck) right off the firewall plug and tied those two together. There is one more wire in the engine's harness that also connects to the starter, but I am not 100% certain on where it goes. But other than the battery cable, this is all you should have to do for the starter.

I also ran a large gauge wire from the positive cable at the battery to the alternator.

For power to the new fuse block, I ran a large gauge wire from the alternator to the fuse block, and split it like I drew in my sketch above; one to the battery side of the fuse block, and one to the relay used for the ignition-on.

For the ignition wire that triggers the relay for the fuse block ignition-on side, I just probed wires coming out of the firewall plug until I found an ignition wire. **IMPORTANT NOTE** Be sure this wire has juice when the key is in the ignition position, AND in the crank position. When mine would turn over but not start, I found that I didn't have any spark at the spark plugs. I started probing the coils and found that I had power until the engine turned over, then I lost power while the engine was cranking. I figured out pretty quickly that I had picked the wrong wire. Once I changed wires, it fired right up.

Hopefully that answers your question, and more importantly, made sense!

[glock35ipsc]

Also, I think the only wires I left coming out of the firewall, other than the light harness wires front and rear; was temp sender, oil psi sender, A/C..... and I think that's it. It seems like there might be one more, but it's not coming to me right now.

[79gmc5.3]

Thanks again Bob. I,m a little confused after reading it but when I get home I will start tracking down these wires and I am sure I will se what you are talking about. The last thing I want to do is turn the key on and fry the whole electrical system.

[glock35ipsc]

LOL, it can get confusing. Then again, I probably go into too much detail sometimes making it worse! I sent you a PM.

[79gmc5.3]

Originally Posted by glock35ipsc

LOL, it can get confusing. Then again, I probably go into too much detail sometimes making it worse! I sent you a PM.

Got it! PM right back to ya! Thanks again! Guys this is what make this the best forum on the net.

[D.FENS]

Originally Posted by 79gmc5.3

Just a couple of pics because I know how much you guy like them. D/S battery tray and test fit on factory filter box. Fits great just like soule64 said it would.

I'd like to go this route and use a factory air box to make the swap look more....factory, lol.

Trouble is, my crewcab has the HD package and there's a big damn battery on both sides. I'm guessing an LSx swap kinda does away with the need for the dual battery system, correct? I think my truck currently has about a 65 or 75 amp system and most GenIII and IV motors I've seen are at least 125amp.

[79gmc5.3]

Originally Posted by D.FENS

I'd like to go this route and use a factory air box to make the swap look more....factory, lol.

Trouble is, my crewcab has the HD package and there's a big damn battery on both sides. I'm guessing an LSx swap kinda does away with the need for the dual battery system, correct? I think my truck currently has about a 65 or 75 amp system and most GenIII and IV motors I've seen are at least 125amp.

Yea I'm not sure what amp the LSx is but you should only need one battery. My goal has always been to look as stock as possible. I really look the look of the stock airbox. Although I have seen a lot of squarebodys that are lowered and it looks great just not sure if I would like it on a long bed. Maybe someone can photoshop my truck lowered with a 3 5 drop

[79gmc5.3]

IT's ALIVE!!!!!!!!!!!!! Holy Crap it fired up within 3 revolutions! Scared the crap out of me! Need to install radiator and clean up the new wiring with wiring loom and it will be ready for the exhaust shop for the new Y pipe and it will be ready to roll! Thanks Bob for the wiring help. Everything was just like you said it would be.

[glock35ipsc]

AWESOME!!!!! So glad to hear that it fired on the first try! That's makes all the hard work worth while.

Great job man, congratulations!!

[bigdnew]

congratulations, now post a video.

[buckshot305]

Awesome!!!! You have done a great job with your truck. I can't wait to get to the same point with mine.

[69face]

great job and congrats!

[STOCKISH]

Good job buddy! Congrats. Glad it fired right up for ya.

[79gmc5.3]

Originally Posted by bigdnew

congratulations, now post a video.

Yea I have to do a few more things like the radiator, trans cooler lines, and just tidy up the engine bay. Honestly last night I had no intention on starting it I was just turning the key to the on position to let the fuel pump run and prime the system and check for fuel leaks and after a couple of times of doing that I thought "I wonder if it will turn over" And 3 revolutions later it fired up! It happened so fast it scared me! Knowing that the trans cooler lines weren't hooked up I just knew trans fluid would be everywhere. It also has open exhaust and was very loud. Scared the wife, she came running out of the kitchen and I was grinning ear to ear. She just said please tell me it is not going to be that loud! But I will try to post a video as soon as I get thing buttoned up. Now I am really pumped

[mcbassin]

AWESOME! to hear it's that close and running! The more I see you guys finishing your conversion, the more it makes me want to get back on our project. Keep the pics coming!