PCM or ECM? - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 10-04-2008, 12:35 PM
onip28's Avatar
onip28 onip28 is offline
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2003 Chevy TrailBlazer LS
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PCM or ECM?

What's the difference between a PCM and an ECM? From what I understand the PCM is the module under the hood or is that the ECM???

I just took my vehicle to a certified GM dealer here in Germany; said I need a new PCM, but when I go to order on GM parts direct, the PCM looks like the module that goes under the back seat and the ECM is what looks like goes under the hood...

Just need verification on what I need before ordering...thanks.

Steven
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  #2  
Old 10-04-2008, 01:12 PM
PulledOverAgain PulledOverAgain is offline
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2005 Chevy TrailBlazer LS
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I've always thought ECM was for Emissions Control Module and PCM was for Powertrain Control Module meaning that is had a transmission controller built into it. I'd almost thing that the one under the rear seat is a BCM (body control module) but i'm not gonna say that since i'm new and don't really know how they are set up. GM seems to do different things on different vehicles and different years.
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  #3  
Old 10-04-2008, 04:16 PM
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onip28 onip28 is offline
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Hmmm...I have the part number in my shopping cart.

Part #: 12574976
Category: Emission Control System Hardware
Description: PCM

http://www.gmpartsdirect.com/cart.cf...TOKEN=22863885

and this from rock auto:

ACDELCO Part # 12574976
MODULE,PWRT CONT(W/O CALN) REQUIRES REPROGRAMMING
* Non-stock item--shipping delayed up to 3 business days

Can anyone else verify the PCM versus ECM...I'm sure that this is the correct part, but to clarify, I need the part that goes under the hood...and from what I understand, that is a PCM.

Any inputs?

Steven
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  #4  
Old 10-04-2008, 04:45 PM
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nateb21 nateb21 is offline
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just a thought but get a hold of Alvin at PCMforless.com and see if he can ship one to you programmed a little better for your application. Just my
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Old 10-04-2008, 04:51 PM
91RS 91RS is offline
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PCM is Powertrain Control Module and ECM is Engine Control Module. There's usually only an ECM if there is a TCM (Transmission Control Module). The PCM combines the two as well as a few other things depending on the vehicle. The module under the back seat is the BCM or Body Control Module. Something like a PCM, you REALLY should order from the dealer so you have the warranty on it in case it is damaged in shipping or for any other reason.
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  #6  
Old 09-01-2013, 05:00 PM
Predateli Predateli is offline
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Thanks for the nice article. It is very useful.
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