Wrong ECM

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Twithers

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Just bought an '04 Tahoe that has had a number of smaller problems I've been trying to figure out:
-The pedal position doesn't read past 57%
-The fuel gauge reads backwards, E when it's full and F when it's empty.
-No oil pressure reading on the gauge.
-None of the "many" A/C blend doors work. All are full cold and won't move to hot at all.
-The driver's seat fwd/rev motion control is backwards. Forward on the button makes the seat move backwards.
-OBD codes are constantly set for fan control relays, when the truck has mechanical fans.
-And others.

I did an ECM scan and, as you can see in the pic I attached, the ECM looks like it's originally from a 2006 Chevy truck. Different VIN also. My Tahoe "runs" fine. No misfire, all things considered has good power, etc. I'm wondering if it's actually a problem that the ECU doesn't match the vehicle 100%. Could that be the actual cause of some of these wierd problems that I've been chasing my tail on? If I wanted to correct the problem, is it just a matter of having the computer reprogrammed with the correct info, or would I need to get a different ECU and have that programmed to the vehicle, since the one in my Tahoe now appears to be from a different year vehicle?
 

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Tonyrodz

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I don't have a helpful answer for you-- when the pcm went bad in my Express van, it needed a new one, which cost around $200 to program to my vin. So I assume that isn't your vin that's displayed. Have you inquired how much it would cost to reprogram it to your vin? You should be able to reuse the existing pcm(ecm). Does the passlock work, or light up on your dash at all? Before starting or while driving? If not, that could be a sign that it's disabled.
 

Fless

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Maybe if you can get the numbers that are on the ECU stickers, you could compare those with a stock one for your year -- see if they're the same. An alternative is to grab a junkyard one from a 2004 and program it to your truck. That way you'd keep the 2006 one for a spare that you know works to make the truck run.

Perhaps you're around someone who has a Tech 2 and can program a different ECU for you. What part of the country?
 

Joseph Garcia

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Should be able to re-program the ECM to the truck's VIN with a Tech 2 and ACDelco TDS / Tech Line Connect.
 

Scottydoggs

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if the vin in the scanner dont match the truck someone swapped the pcm, or its tune.

thing that gets me is, the bcm controls the seats and actuators. so maybe it was flooded out and they just replaced parts from a newer truck. or the body got swapped onto a newer frame? idk, its odd for sure.
 

Mudsport96

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The 06-07 trucks have a different pedal and TAC module wiring setup so that is the problem with that. If you have an 06 computer in a pre-06 vehile you will have tps codes. As for the rest... i would assume the same. There are a few hardware differences in ecms, but that typically affects drive by cable vehicles. So of you can get to a dealership or reputable garage with a tech2 have them reprogram the ecm to your vin and you SHOULD be fine.
 
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Twithers

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It's strange that I don't have any codes in any of the systems relating to the throttle position system. Just the position not reading higher than 50-something percent. As I've said in my posts in other sections, I've decided that I need to get a correct ECU before I go any further on all the wierd problems with this truck. Who knows what all will clear up when I go from an ECM for a 2006 6.0l truck to a 2004 5.3l Tahoe. I'm surprised it currently runs at all.
 

Mudsport96

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It's strange that I don't have any codes in any of the systems relating to the throttle position system. Just the position not reading higher than 50-something percent. As I've said in my posts in other sections, I've decided that I need to get a correct ECU before I go any further on all the wierd problems with this truck. Who knows what all will clear up when I go from an ECM for a 2006 6.0l truck to a 2004 5.3l Tahoe. I'm surprised it currently runs at all.
PART of the reason you dont have codes is being the wrong operating system it doesnt know there is a problem.
As for the other stuff that may be a body control module like stated above. If it has one wrong computer who is to say the other isnt wrong as well?
 
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Twithers

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So, I found an ECU from an '04 Suburban with the 5.3l. It has the same part number as what I "think" my Tahoe is supposed to have, 12586242. Hopefully, other than having the wrong VIN, it will clear up some of the wierd stuff going on, so I can focus on what really needs my attention. I'll try to remember to come back and close the loop on this after I get it. If
 
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