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2005 CTS
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Discussion Starter #1
2005 CTS 3.6l, 130,000mi. ran perfect until a few months ago. now it has been shifting rough, running rough, all gauges quit working, and my high beam indicator blue light constantly flashes. I have looked through several hundred threads and I think I may want to get a refurbishhed ECM that is programmed for my car for 345.00, from www.acrautos.com.
Any thoughts?

Thanks,
Doug
 

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'05 CTS-V
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8,047 Posts
All the fuses are good? Grounds OK everywhere? I would be more inclined to think those sorts of problems would be signs of a bad BCM (body control module) rather than ECM.

I'll try to remember to take a look in my 2005 FSM this evening to see if I can find those symptoms somewhere. Are you getting any codes (CEL on?)?
 

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2005 CTS
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13 Posts
Discussion Starter #3
thanks for the response.
fuses are good . no check engine light.
I havent really looked too hard for ground wires. I can start looking for those and make sure they are good. Any particular areas to hone in on?
If I don't find any obvious grounding issues, would it make sense to purchase a BCM first?
Then, if that didn't help, go for the more expensive ECM?

Thanks again,
Doug
 

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Super Moderator
'05 CTS-V
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8,047 Posts
I took a look in the FSM, but everything basically tells you to hook up a diagnostic tool (presumably the dealer's TechII) to see how the various modules are communicating.

My suggestion that it could be a bad BCM isn't much more than a guess. The ECM definitely doesn't input to the high beam indicator, for instance, and although the ECM provides input to the various gauges, it doesn't really control them, so I wouldn't expect a bad ECM to cause the instrument cluster to just completely shut down.

Is your Check Engine Light on (I would think it must be based on your description of the car's behavior), and if so, have you gotten the codes scanned anywhere?
 

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2005 CTS
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Discussion Starter #5
thanks for the reply. I am finally ready to start working on this car again. More than likely, there is more than one problem so Id like to tackle one at a time.

the check engine light is not on. and there are no codes that I can see.

so if I purchase a new BCU and install it, I will still need to take it to a dealer to program it to my car - correct? if so, will I not be able to see any changes until they program it? or should the gauges start working right away?

hopefully this will clear up the dash lights and gauges. then I can work on the crazy shifting and missing.

thanks again,Doug
 
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