I know I am doing this backwards. I had a 2wd 2001 lb7 that had 468000 miles on. My nephew totaled the truck so I pulled it and did a complete rebuild. I picked up a 4x4 2004.5 with a lly. I pulled that engine and installed the lb7. I thought it was plug and play. The connectors are different on a few things. I have changed engine harness transmission harness to lb7. Ecm tcm fuse block. I just need to figure out the harness coming from the dash. The plugs are different.
LLY to LB7
- Thread starter FCmills
- Start date
01-02 is a COMPLETELY different wiring architecture than 03-07. They do NOT just interchange. You won't find much info for putting an 01 into an 04 as most pull LB7's yo put in LLY's. You have opened up pandora's box to be honest. This will be alot of custom wiring. And do NOT assume that just because it plug's in, it us right. 02 to 03 was a MASSIVE wiring change.
You’re in the right spot, it’s just like FERM said, not many people have gone this way and there isn’t much info to be shared since that’s the case. You may be better off getting the electronics from an 03-04 lb7 to use. I would imagine you will have countless hours tracing and making new harnesses to make the truck function properly. The 01-02 use a standard style of harness whereas 03 and up use a canbus system and they aren’t compatible in the least bit. You will essentially have to rewire the entire truck to make an 01-02 harness and brain work in a newer truck, basically turning it into an 01-02 truck. As far as I know, everything will be different, from window switches to the BCM to your lighting circuits. I could be wrong on those, but I do know they communicate differently. It’s the same concept as the differences in 95-99 and 99-02 trucks. Nothing will be plug and play. A stand-alone harness might be an option but I don’t know that for sure. In theory it would work but not sure if you’d lose functionality in other parts of the truck.
I’m not 100% sure what all is different from 01-02 to 03 and up. If I’m not mistaken some of the engine sensors are different on the early engines as well. Not sure if there’s a difference in ECM, TCM, FICM, things like that. Basically what you need to do is search some of the LLY swaps on here. I know James did the swap on his 02. You’ll have to reverse engineer it based on the things he had to change to make the LLY platform communicate with his early truck.
If you're going to put an LLY into an 01-02 LB7 truck, you're probably going to have to convert all the truck electrical over to 03-06 to match the engine. That means cluster, hvac control, bcm, etc.
Now, saying that.....wasn't there a thread on here years past about seeing an LLY in an early truck? Title was something like, "Now I've seen it all...." or like that???
Now, saying that.....wasn't there a thread on here years past about seeing an LLY in an early truck? Title was something like, "Now I've seen it all...." or like that???
I remember that thread Tom. I tried searching for that title and it didn’t bring anything up and “lb7 in LLY” came back with an error message.
Bingo!
www.duramaxdiesels.com
I have seen the impossible!
First I will start saying I dont have pics. So if you dont belieive me I understand. At the truck pull this weekend It was a 2001 GMC with a LLY motor in it. At first I did not beleive the guy when he said it. He then popped his hood and proved me wrong. He claim that he was able to use...
www.duramaxdiesels.com
The thread you're thinking about was using an LLY top end on an LB7 short block with LB7 electronics. The OP is trying to do the OPPOSITE, he is trying to put an EARLY LB7 into an LLY truck. That involves swapping EVERYTHING over to 01-02 wiring, and even swapping the fuel tank.
To the OP, if you switch your 01 over to an 03-04 LB7 harness and ECM, it is all plug & play. 01-02 is a different animal from 03-07 classic.
To the OP, if you switch your 01 over to an 03-04 LB7 harness and ECM, it is all plug & play. 01-02 is a different animal from 03-07 classic.
Thank you all for the help. I think I am going to take the engine back out and get the lly heads ready to swap over to my lb7. I hate to but it seems the best route. I had new injectors and new everything. If some reason I do keep it in. Your saying if I buy a 2003-4 lb7 engine harness it will plug up to the lly wiring from the dash?
I just read through all 13 pages of the thread Tom posted. Very good read that may have some info you could use. If I’m not mistaken, yes. You should be able to get an 03-04 lb7 harness and ecm and make it work.
Yes, the 03-04 harness will plug right in. There are a few changes you will have to make like swapping out the 1 wire oil pressure sender for the 3 wire pressure sensor, and since yours is an 01 I believe you will have to alter the boost sensor wiring as GM moved it and slightly changed the intake for 02-04 vs 01. GM wiring can be looked at as 95-02 and 03-07 classic. From 95-02 most everything was hardwired, in 03 they went to control modules everywhere that greatly reduced the amount of wire that went into the vehicles. And yes, I said 95-02 even though they are 2 different trucks. That is how it was so easy for me to wire my 01 Duramax into my 95 Suburban, the wiring color codex and architecture were very similar.