Help identify this part
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From: San Antonio
Help identify this part 
I'm trying to figure out if this harness has a PCM. I see two boxes in this pic, but I'm not sure if one is the PCM. Is the box in the center the PCM? This supposedly came off a 2009 Silverado with a 5.3l
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From: San Antonio
Oh, so it is a PCM. It looks different from mine. I guess the gen4 stuff is different.
Can this PCM be used on a gen 4 engine in my LS1 Camaro? I'd really like to put an L76 in my car.
Can it be used on any vehicle that came with a gen3 motor?
Can this PCM be used on a gen 4 engine in my LS1 Camaro? I'd really like to put an L76 in my car.
Can it be used on any vehicle that came with a gen3 motor?
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From: Shlumpt, TX
That is how my pcm looks on my 99 Silverado.
No a 4th gen PCM cannot be used with a gen3 engine, not without a lot of extra work. It is much easier to do it vice versa with a gen 3 pcm and gen 4 motor.
You can easily stick an L76 in your Camaro with your current PCM. There is 0 need to swap PCMs
No a 4th gen PCM cannot be used with a gen3 engine, not without a lot of extra work. It is much easier to do it vice versa with a gen 3 pcm and gen 4 motor.
You can easily stick an L76 in your Camaro with your current PCM. There is 0 need to swap PCMs
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Well, I would like to the have option of flex-fuel. My PCM doesn't have that table in it. I also figured that I wouldn't need the knock sensor harness or cam/crank sensor switch box. Those "conversion" parts are several hundred dollars. I can get this Gen-4 harness for $65.
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From: Shlumpt, TX
If you could use the gen 4 pcm there wouldn’t be a need for conversion parts 
But on trucks you can upgrade the OS to support flex fuel and do the required hardware mods. My 99 OS doesn’t but an 02 does from what I remember. I would look around at getting a newer OS or get a gen 3 computer which I just so happen to have and have flex fuel put on it
But on trucks you can upgrade the OS to support flex fuel and do the required hardware mods. My 99 OS doesn’t but an 02 does from what I remember. I would look around at getting a newer OS or get a gen 3 computer which I just so happen to have and have flex fuel put on it
I read were people have been able to install a flex fuel sensor and set it up on the 411 ECM but I'm not certain if it really worked correctly which is why the P59 ECM was the one to try this with. Been doing some reading on the subject of flex fuel because I'm interested in running E85 and it would be nice to be able to run the car from the local pumps regardless of what time of the season it is but I've been told if with a 411 ECM just tune it for C85.
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I thought people were just getting the conversion parts because the Gen-4 harness/PCM is harder to come by. A lot of people just cut the harness when they pull the engine from the wrecking yard.
I understand why a Gen-3 engine PCM won't work on a Gen-4 engine without the conversion stuff. I guess I still don't understand why a Gen-4 harness won't work on a Gen-4 engine in a "Gen-3" vehicle. That engine/PCM are literally made for each other. Does it have something to do with the instruments in the vehicle? I think they still had the same transmission options at that time.
I understand why a Gen-3 engine PCM won't work on a Gen-4 engine without the conversion stuff. I guess I still don't understand why a Gen-4 harness won't work on a Gen-4 engine in a "Gen-3" vehicle. That engine/PCM are literally made for each other. Does it have something to do with the instruments in the vehicle? I think they still had the same transmission options at that time.
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From: Shlumpt, TX
because the harness won't match up to the gen 3 PCM. You realize the PCM does not care about what engine is attached to it right? That is why we are able to do stuff like 408s. There is no 408 PCM but we can modify the PCM to understand. That's why you can use a V6 PCM to work on a V8.
Nowadays most wrecking yards include the harness and PCM with the engine, that is how I received my last one and that is how most of them are marketed.
I mean you might be able to put in a harness a pcm and engine from a Gen-4 but it would take some work to get the gauge cluster to work properly, to get the AC to work, to get a lot of stuff to work together. It is something that is just not worth doing. You would be spending more money and time on that then you would on just tuning the Gen 3 PCM.
Engine does not care what is attached to it, PCM does care what vehicle it is in but not the attached engine. That is the rule.
Nowadays most wrecking yards include the harness and PCM with the engine, that is how I received my last one and that is how most of them are marketed.
I mean you might be able to put in a harness a pcm and engine from a Gen-4 but it would take some work to get the gauge cluster to work properly, to get the AC to work, to get a lot of stuff to work together. It is something that is just not worth doing. You would be spending more money and time on that then you would on just tuning the Gen 3 PCM.
Engine does not care what is attached to it, PCM does care what vehicle it is in but not the attached engine. That is the rule.
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I suppose this harness could be used for testing/running engines on a test stand in a shop. In that scenario, a laptop would be connected to it in order to monitor the "gauges".
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From: Shlumpt, TX
If we could use the Gen 4 harness there would be no need for conversion parts. You are not going to be able to use the Gen-4 harness and PCM it just will not work. The PCM function is much different than the Gen 3 function. So no you cannot.
Yes you could use this harness to test engines on a test stand though and that is probably the best part of it if you have an older engine. Well at least if you have all the conversion parts to hook it up to afterward.
Yes you could use this harness to test engines on a test stand though and that is probably the best part of it if you have an older engine. Well at least if you have all the conversion parts to hook it up to afterward.
