72 GMC Longbed Duramax Swap

[NathenMyers]

Edit for clarification

this plug in the picture will plug directly into the ignition switch, which then plugs into the 2005 key assembly.
so: picture-ignition switch-key assembly


what i'm looking for is what each of those wires do, because i'm going to splice them into my actual 72 ignition switch


thanks!!

[gerfunken]

Not sure if this is exactly what you're looking for.. but I was able to find this for you:

http://www.bulldogsecurity.com/diagr...eID=54&link=DW

https://www.gmupfitter.com/publicat/...lectric_CK.pdf

[NathenMyers]

thank you so much!
i'm trying to decipher these now!

[6BT 56]

Hey I may be late for the party but I can shed some lite on your wheel question.

I had 16 inch gm steel wheels all ready for my 56 with Dana 60 rear . My wife's 02 burb 2500 4x4 , likely same rear , or actually maybe even smaller than yours rear needed rubber for the winter .

My great plan was to buy nice new bfg at for the 80's gm 16 inch steel wheels , run em on the burb for the winter and then put them on the 56 in the spring and retire the burb. Got them all mounted up and ready to go and the dam rears won't fit over the calliper on the aam rear . Both rears are 16 inch but the gm aluminum wheel are cut out huge on the inside vs. the old 16 inch gm steel wheels . Hope I'm not being a party pooper . Just hoping to save you the poop I went thru .

[NathenMyers]

oh man i didnt even think about that. thank you!

[NathenMyers]

OK guys, I'm having a little panic, and i need someone to talk me off of a ledge

first: when i have the 2005 ignition switch connected to all the wiring (like it should be) the truck cranked, started, and ran just fine.

second: i took apart the ignition switch (which was kinda neat) to see how it worked. Looking at the switch, and the bulldogsecurity diagram that gerfunen so kindly helped me with, it LOOKS like at the ON position: pink(ign1) red(always hot) and brown(acc2) are switched together; also orange(acc1), white(ign2), red(always hot) were all switched together.

third: when you flip the switch to START the Yellow switches on with the orange, white red, and it cranks and starts.

so, in an effort to make sure this theory was correct, i fixed myself up two switches, and engaged them. crank no start.

put the stock switch back in place, crank no start.

i'm having a moment of panic, worried that because i had them all switched "on" while it was cranking that i blew something....

i found a blown 20A fuse in the (i think) Aux PWR slot in the underhood fuse box. But, i don't know why that would be connected to my problem.

if anyone has any insight it would be great! ... you can also tell me i'm dumb if you have to...

thanks!

[6BT 56]

Glad I could help with the wheels . I saw your post when I was catching up and saw the comment abt the wheels and thot I needed to chime in to prevent you from having the trouble and expense I did. I just put similar vintage caps on my 56 . They look period correct for a lot of old trucks Maby look into some steel wheels for a 2002 and newer truck . They must fit over the callipers and maby ??? Can fit a hub cap???

With your wiring issue dosent the eng have multiple relays for ecm crank fuel pump and so on ? Isn't the key switch just triggering the relays with no direct path to the ecm? If that's the case not to likely to Make the ecm take a dump. Just my thoughts , come on in of the ledge pls . Lol

[NathenMyers]

thank you for that!
i was thinking to myself that surely there was someplace for the electricity to dump out before it hit the ecm. but really, all of those wires are connected through the stock switch, i just engaged them in the wrong order. so i wouldnt THINK it would blow anything. but. i went from cranking and starting, to just cranking. so i'm not sure.

[BigRed76]

Have you checked for any codes in the ecm? Maybe trying to start the engine without the proper circuits powered caused a code to set preventing starting.

[NathenMyers]

thank you for that idea! i haven't checked for codes! i dont know why that hadn't come to mind....

[NathenMyers]

alright!
Figured it out!
i'm dumb! haha!

basically what happend, the day all of this started showing up, i had ALSO installed my twin kennedy lift pumps. To do that, i drained my fuel lines, and never re primed anything. so, the reason the truck wouldn't start was: i was sucking air!

thank god!

now that i have that hunted down, i'm good to keep rollin'!

thanks for the suggestions and help you guys!

[NathenMyers]

Joyous news!

I finally started the truck with the 72 switches! It looks like we have everything worked out!

so, i don't have an actual diagram, but i'll give the lowdown here, for anyone that is looking for the info... the way that i've spent the last few weeks trying to figure it out!

2005 Duramax LLY Ignition Wiring

full disclosure, i have the full "in cab" 2005 harness AND the full 72 harness in my truck also. I'm sure some of you more experienced fellas could have done this more elegantly, and with less wiring but i'm still learning!

I took the 2005 Ignition switch apart, and it looks like in

Position 1(accessory): Pink (ignition1) and Red (always hot) are engaged

Position 2(run): Pink(ignition1), Red(alwayshot), White(ignition2), Orange(accessory/Heaterblower1),Brown, Red(a second alwayshot)

Position 3(start): red(always hot) Yellow(Starter) Pink(ignition1) White(ignition2)

So, while i was testing to figure out what actually needed to be hooked up to make it start and run. I fashioned 2 switches.
One toggle: Red(always hot) and on the other post i had Pink(ignition1) and White(ignition2)
Pushbutton switch:Red(always hot) Yellow(starter)

It started and ran! So, bare bones start and run works!

Now, to marry it to my 72 switch and harness!

Basically, i wired the 2005 ignition wires (Ignition1, and Ignition 2) to the 1972 Ignition Coil Wires (i had to run them back through the firewall). and the 2005 Yellow(starter) wire to the 1972 Purple(starter) wires.

finally started right up! If you guys have any questions about it, or i've been unclear ( super possible ) Let me know and i'll try to streamline this some!

[PowerdbyChevy79]

any updates ??

[feller]

He's driving it now, he drove it to my house a couple of weeks ago, about 40miles one way. This thing is awesome and it looks and sounds amazing.

[NathenMyers]

Sorry Guys! long time no talk!

You know how it goes....

so, It's been up and running, i've put about 10 tanks of fuel through it. Like feller said, i drove it to his place.

I've been trying to get my steering situated, then my fueling... and now three glow plugs that are broken off in the head....

it's been a rough year!

however, fueling is fixed, and running again. Working on steering, i started a new thread over in the suspension forum trying to figure it out.

First start from about a year ago: https://www.youtube.com/watch?v=_1CjK6QTifI

first 20 seconds of the first drive: https://www.youtube.com/watch?v=SHf3r4qWMhU

[Dieselwrencher]

Very nice! Stinks about the glow plugs but you'll get it handled!

[Dan Castilleja]

Originally Posted by NathenMyers

You'll have to excuse the Horrid Quality pictures, my phone is a tad scratched up. However, next weekend when we work, i'm taking my actual camera.

Dude in the ball cap is my dad, holding my nephew.
The guy in the black shirt is one of our best friends that realistically is going to be doing most of the work while i hold the flashlight. That dude is Charlie Daniels of the torque wrench.

What engine mounts did you use?