L83 -> lm7 can it be done?
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L83 -> lm7 can it be done? sooo i have a 2014 Silverado i recently hydro-locked and have found a LM7 drastically cheaper than a replacement L83 my question here is it interchangable and if so how much hassle will it be? from what ive seen the older engine doesnt have the afm/dod which im fine with because i shut it off on the current engine. so all in all should i bite the bullet or go the cheaper route?
Joined: Apr 2006
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From: Grand Rapids, Michigan
There is ZERO chance the "cheaper route" will be cheaper. Find an exact replacement engine. Your ECM will not run an older engine, the entire exhaust system from the cats forward will have to be changed, and likely numerous other things that will cause the cheap initial price of the LM7 to be a moot point. I've seen 2014+ 5.3's for $1500 or less. Keep looking, you'll find one.
TECH Resident
Joined: Jun 2011
Posts: 936
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You're trying to from a GENV with 6-speed (which has a built in TCM) to a GENIII engine.
For everything on the truck to work properly the ECM has to be able to talk to both the TCM and the BCM. If the TCM and/or BCM are missing any signals could cause erratic driving behavior, gauges not working, and other functionality problems.
The GENIV ECM from 2009 to 2013 also use a 6L80e, so there's an outside chance it could talk to the TCM properly (no idea for certain), but even if so, you still have the BCM compatibility between truck generations to worry about (and the VINs of the BCM has to match the ECM requiring reflash with a Tech 2). For argument's sake, let's say you manage to get all that sorted out and can succesffully use a GENIV ECM in a 2014... the LM7 (GENIII) still isn't setup to run on a GENIV ECM! So now you have to change some hardware as well (wiring harness, modify the block to relocate knock sensors, 24x to 58x crank sensor setup, etc. etc.).
Big gamble on whether you'd get it all to work properly, and by the time you do all the necessary changes, it'd be way more expensive than a replacing with the correct engine.
For everything on the truck to work properly the ECM has to be able to talk to both the TCM and the BCM. If the TCM and/or BCM are missing any signals could cause erratic driving behavior, gauges not working, and other functionality problems.
The GENIV ECM from 2009 to 2013 also use a 6L80e, so there's an outside chance it could talk to the TCM properly (no idea for certain), but even if so, you still have the BCM compatibility between truck generations to worry about (and the VINs of the BCM has to match the ECM requiring reflash with a Tech 2). For argument's sake, let's say you manage to get all that sorted out and can succesffully use a GENIV ECM in a 2014... the LM7 (GENIII) still isn't setup to run on a GENIV ECM! So now you have to change some hardware as well (wiring harness, modify the block to relocate knock sensors, 24x to 58x crank sensor setup, etc. etc.).
Big gamble on whether you'd get it all to work properly, and by the time you do all the necessary changes, it'd be way more expensive than a replacing with the correct engine.
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I appreciate the input from the both of you! In my area a low mile L83 is around $4500 so I was looking into other options im used to imports and there interchangeability so I figured 5.3 g3 v 5.3 g5 may be compatible. Thanks for the info!
