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Rawze · 10-27-2025, **(Subject: Ecm issue )**

(10-27-2025 )JTX Wrote: Old engine 80020974 cpl4343
New engine # 80477559 cpl 5880

old esn 80020974 comes back to an X15, CM2350 BGT engine.

new ESN comes back to an X15, CM2450 BKR engine.

These 2 engines are nothing similar whatsoever.

(medaphor)-Just because they both might say 'Ice Cream' on the outside of the carton,.. does not mean they are the same. One might be chocolate... and the other might be lemon or bacon flavored inside it.

Those 2 engines are not even in the same technology with each other /.., and especially so for the the engine control modules.

The older BGT Cm2350 ECM will run that newer BKR engine model internals with no problems ... so ... What needs to happen is that you need to use the wiring harness and ecm from the old engine on the new long-block and not use the newer wiring or ecm. Then a custom program needs to be written for the older ecm that will properly run that ewer model engine. The older ecm will also already be set up correctly for the truck, oem harness wiring, dash, J1939, etc. and everything else.

I typically end up writing custom programs for those type of 'completely different model engine' swaps many times a year for people, even sometimes for stealers$its because they just don't know any better and end up putting in an engine that is not even remotely compatible with the one they took out,.. simply because they both had the letters 'ISX' on the side off them, not knowing any better. They think that they are mostly the same somehow, but this is a as far from the truth as it gets.

Also the emissions systems are NOT going to be compatible at all.. and it is just as illegal to try to run the old emissions systems on the new engine as doing s delete.. so a de-mandate will also have to be done to get it running right as well (can be done when new program is made for older ecm). This means that If you wanted to keep it 100% legal.. then you needed to source a replacement engine that is the same make/model era (a BGT engine) as the old one instead of trying to put a completely different model engine in the truck.