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· Registered
2006 CTS 2.8L V6
2 Posts
Discussion Starter · #1 ·
Hi new here, so thanks for any help!

My 2006 CTs v6 2.8l with 133k is acting odd to say the least. I recently self swapped out the head unit (non bose system) using this PAC Audio wiring harness designed for CTS
"PAC Audio OS-2C-CTS "

Link to product here: ( i mention this b/c i thought it might be the cause for reasons i will get into later)

all was running fine for two weeks then suddenly one day I got home, turned off the car and couldn't get the key out of ignition. i soon realized the anti-theft light was on.
In every other anti theft issue ive heard of and researched so far however- the car is unable to start. however with my car- I can start, drive, shift, use the stock radio, go wherever I want.
The only issue is the windows won't roll down, and the driver's side door only- will automatically unlock itself when i use the button to lock all the doors. (they all lock, then driver door will unlock).

i took it back to the small dealership i got the car from, they checked it up and down, even swapped the door control module around with another one and tested my old one in another CTS and found no issues with it.
They claim they had an issue communicating with the ECM and that the PAC audio was the culprit because it smelled burny. they put the stock radio back in.

I am not sure they have the right tools to know that it is in fact an ECM issue, they didn't seem to understand auto-electrical too well. (NOT A CADDY/GM DEALER).
i was under the impression that an ECM controls all sorts of things including mechanical operations of the car- wouldn't a TON of stuff not be working including shift timings, fuel injection, etc if the ECM were fried?

Anywho, I've researched a ton of stuff, tried a few solutions nothing seems to work. Now it seems like my battery might be the culprit - OR I have some kind of parasitic draw on the battery b/c it runs out of charge and I have to jump it every other day.
i also read that a battery running inefficiently can cause weird issues with the anti theft.

-i don't think its the alternator, b/c if the car gets started with a jump, I can take it from here to china ON THE WATER on magic car skis and it' be fine- if its turned off its hit or miss if it turns back on
-the "hit or miss" turn back on has gotten progressively worse. To the point where i had my friend jump my car to start it, let it run for 15 min, shut it off, wouldn't start again without a jump.
-the 30 minute relearn isn't an option because the theft light NEVER disengages even after the car starts and becomes drivable.
- the dealer removed my solenoid so that i can always take my key out of the ignition, anti theft or not.
- if the car starts strong radio will come on with the car, however if the battery is "lower" my radio will not turn on with the car, if i drive it for a minute, then crank the key briefly while driving- the radio will pop on.
-the radio does say "service theft system" but i think it just says that by default when the antitheft light is on.
- i do not even own, and never had with the car the remote key entry, just a regular key.

Another thing that bothers me is all the replacement batteries i see for this car are like 600 CCA minimum but mine is 550 cca and doesn't seem to take up the whole battery cage. Could they have stuck me with a weak battery to begin with, doomed to eventually die off in this car?

ANY suggestions would be helpful, TYVM!!!!!

· Registered
2006 CTS 2.8L V6
2 Posts
Discussion Starter · #2 ·
Update: new battery today.
found out my ex battery- the size 75- wasn't even the correct size. should have been 101. the dealership i bought the car from had that 75 size battery in there. found out i guess this can cause a multitude of issues.

wondering if any1 knows anything about this specifically. anti theft stuff still acting funny and cant do the relearn.

car runs and drives, radio is good too.


^amendment, the old battery had also gone bad, Auto zone charge dit for 1 hr and it maintained nothing.
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