LB7 to LB7 swap

knagel

weakest link finder
Jun 4, 2007
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Central, Iowa
I tried searching but didn't really find the answer i was looking for. I am in Iowa and have a great running 2002 LB7 but the truck needs to be retired due to rust. I have been searching down south for used LB7 trucks and there doesn't seem to be very many 2001/02 trucks. There are more 03-04 LB7 trucks available. This is a work/plow truck so it doesn't have to be fancy, just looking for one that you can't throw a cat thru.

I have read that 01-02 does not play well with 03-04 LB7. Like its not plug and play. I am ok with that. My question is what needs to be changed on the 02 I have to make it drop in to an 03-04 body? Surely an LB7 is an LB7, its just the sensors and wiring that makes them different so they dont play well. So is it possible to just make the 02 LB7 say an 04 LB7 by putting the sensors off the 04 on to the 02 and then drop it in?

Ultimately I am looking for a truck with a blown engine or trans so I can use mine as a donor.

Thanks in advance,

Kevin
 

2004LB7

Well-known member
Dec 15, 2010
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Norcal
if you swap over the 03/4 harness to the 02 engine, there are a few things you'll need to change too. off the top of my head, oil pressure sensor. can't remember what else but others will chime in.
 

knagel

weakest link finder
Jun 4, 2007
219
1
16
Central, Iowa
That's what I was wondering. Basically take all the engine harness and sensors off the 04 and put them on the 02 and should be good to go?

Any info you guys can put up is greatly appreciated! I have been told to just stay with an 02 body because it will be easier. But there has to be a simple way to do it if I have a chassis that is an 04 LB7 to just take out the motor, swap harness and sensors to make the 02 an 04 LB7 and put it back in. Unless they changed like crank or cam timing on them and the internals will not work with 04 sensors/harness.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
That's what I was wondering. Basically take all the engine harness and sensors off the 04 and put them on the 02 and should be good to go?

Any info you guys can put up is greatly appreciated! I have been told to just stay with an 02 body because it will be easier. But there has to be a simple way to do it if I have a chassis that is an 04 LB7 to just take out the motor, swap harness and sensors to make the 02 an 04 LB7 and put it back in. Unless they changed like crank or cam timing on them and the internals will not work with 04 sensors/harness.
Yes.
 

knagel

weakest link finder
Jun 4, 2007
219
1
16
Central, Iowa
So no internal or external differences in the 01/02 to 03/04 engine. Just use everything (harnesses and sensors) off the 04 and put the 02 engine in the 04 correct?
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,312
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Mid Michigan
Well, there are differences in the 01 to the 02, and then to the 03-04.
01 does have different sensor locations,such as MAP (the intake piping is different), and the oil pressure sender is in a different location.
02 is similar to 03-04 in sensor locations, but the wiring architecture is different on 03-04, like James said.
One can tell GM was changing things as they went back then.
 
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knagel

weakest link finder
Jun 4, 2007
219
1
16
Central, Iowa
Thanks for the info! I might have found a rust free 02 with bad cups i can get fairly cheap so I may go that route.
 

rfletes79

Active member
Mar 5, 2010
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Galt, Ca 95632
01 & 02 have the same eop sensor. Y bridge is different in those as well.

03 and up have the same eop sensor. These sensors and harnesses are not interchangeable with the 01/02 engine harness.

Federal engine harnesses vary slightly depending on year, map location, jumper harness, eop/oil level harness

Federal 02-04 all share the same ybridge and ic plumbing. Cali lb7’s exist for 02-04, if your truck is federal stay away from the cali lb7. Too many differences.

As far as the chassis harness (ecm/tcm side) surprisingly they all interchange and will run regardless of the year or emissions. Only real difference is the ac connector and wiring for it. 01/02 same 2 pin connector. 03/04 same 3 pin connector.

Essentially regardless of the year you purchase, it will work. Just use parts from the right year to make all the connections like it needs to be for that specific truck.

Rick


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