02 lb7 into 01 burban 2500

LaytonBarnwell

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Jan 5, 2022
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Hey y’all new guy here. I’m embarking on a swap from my (wrecked) 02 lb7 4wd into my new to me 01 suburban 2500 4wd. I have read all over about “stepped” body lifts, from .32”-2” but cannot find them anywhere. I also can’t find a detailed instruction on what wiring needs to be done to run my glow plugs with the suburbans wiring harness. Y’alls help would be appreciated!
 

Mikey52

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Sep 20, 2018
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You will need to use your harness. From the lb7. Modifications will need to be made. Never done the swap, but a few on here and other forums have. I've seen it recommended to use same year model for swap as it's easier.
 

TheBac

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Apr 19, 2008
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Duramax core support/radiator is 2" taller than the gas counterparts, hence the need for the body lift pucks. Being you're using a 2500 Sub, though....it might all fit without the lift. You'll just have to deal with it when the time comes. This thread has the puck heights: https://www.dieselplace.com/threads/where-to-buy-progressive-lift-pucks-for-suburban.770609/

Found this write up. It may help you: https://www.dieselplace.com/threads/yukon-duramax.148819/page-6#post-2134993
The 2500 Sub is like the 1500hd/2500 pickup as far as frame and body height. You either need a 2" body lift or the staggered lift blocks to fit the Duramax core support into a 2500 Suburban.

You will use the Duramax engine/trans harness but use the Suburban body and other harnesses. You have to run a wire to the cluster for the wait to start light to work. You also have to rewire the ECM relay so that the ECM controls it instead of it being switched on by the ignition switch like gassers do so you don't get the P0612 code.

Getting your fuel gauge to work with the factory dual tanks and the fuel transfer pump is 1 of the biggest jobs to do. You have to take the gas fuel pump out of the front tank and put in a Duramax pickup assembly. The rear tank unit can be kept, but I highly recommend putting a check valve in the line going from the rear tank pump to the front tank so fuel cannot transfer via gravity. The Duramax ECM freaks out if the levels don't move how it thinks they should, and defaults the gauge to empty. It is also recommended to modify your fuel filler so that each tank has a hose going up to the filler to prevent fuel from sloshing from 1 tank to the other.

You have to modify the wiring so the ECM powers the rear transfer pump instead of the front tanks fuel pump. The pump relay in your fuse panel ran the front tanks pump and there is an auxiliary relay mounted outside your fuse panel that runs the rear transfer pump. When you hook the Dmax harness into your Suburban harness, it's fuel pump trigger wire will command the pump relay in the fuse panel that originally powered the front tanks pump. And the final step is to get a cab & chassis dual tank OS in the ECM, correct the tank sizes, and setup the level unit values.

I'm sure I'm overlooking alot of stuff, but this is a basic rundown. If you're on fakebook there is a duramax swap group with alot of info in it.
 

markmx6

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Jul 17, 2021
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If anyone is curious, I found an easy solution for the rear fuel pump issue on my 03. If you take the primary fuel pump relay out of the suburban fuse box and short the 2 pins that activate the pump (since there is no longer a pump there it doesn't do anything) it will provide power to the secondary pump relay. The wiring was already connected in the wiring harness from the new ECM to the vehicle. So nothing else needed to be done.