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2007 Cadillac CTS 2.8L
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New here ... Service Theft & key stuck even AFTER replacing ECU/ECM and key relearn

Have a 2007 Cadillac CTS 2.8L Base

I've literally read all the forums and replies based on the problem I am having, so if anyone can help me from here out I'd really apprecaite it. :highfive:

The car gave me the service anti-theft system error, and the security light and TC light on dash came on, with key stuck in ignition, no gas gauge work or temp gauge. Car starts normally and runs perfectly fine, I just have to release the key manually through the pin hole.

After hours of research and diagnostic, I pulled the trigger on a ECU/ECM, replaced it and did the key relearn, but still the same symptoms.

Here is what I've done:

-checked all fuses -- OK
-checked battery -- OK 15 + volts consistently
-replaced ECU/ECM and relearned key - OK
-No engine light
-no error codes when scanned with latest scanner except u1000
-key is OEM not aftermarket
-did battery reset/fuse resets...locked door with car remote and re-open with key...all the little things and still no luck...

Only code still showing is u1000.

At this point what can it be?

-key ignition issues?
-ground ? (where the hell do i start with this one?)

Anyone with any suggestions please help!
 

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2007 Cadillac CTS 2.8L
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Discussion Starter #2
Re: New here ... Service Theft & key stuck even AFTER replacing ECU/ECM and key relea

bump...


damn wheres the love in these threads....
 

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2003 CTS
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147 Posts
I'd say the first thing is to have your battery tested. U1000 is a communication error ( a weak battery can cause this) stating that the battery puts out 15+ amps... Is another sign of a bad battery. Should be only low 14's when running. Key stuck...another bad battery sign. So thats where I would start. I had a 14 month old battery when this happened to me. Long story short... Battery had a bad cell. New battery fixed that problem. Have your battery tested, if it's good take it to a dealership for diagnosis. Hope this was some help.
 

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2007 Cadillac CTS 2.8L
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Discussion Starter #4
Re: New here ... Service Theft & key stuck even AFTER replacing ECU/ECM and key relea

appreciate your help...dearly...i know this is an older vehicle so not much support for it online other than previous posts...and i know i am new here and don't have much clout but i appreciate your response and time, and anyone elses for that matter.

it would be amazing if it was my battery after spending so much money into it...its less than 10 months old, is it possible for a battery to go bad that fast?

some more updates:

-changed the brake switch relay...this was to make sure the computer knew what gear the car was...some said that the car may not realize it is in PARK and the key would not release...which was true, because when i connected the TECH 2 scanner, it would show 5th gear, however the car would be in park, i thought it would almost certainly fix it cause it made too much sense...

but it did not...however it did fix the computers knowledge of which gear the car was....also checked the linkage underneath for the tranny and gear box, everything looked fine...

I am just going to go over to Canadian tire and exercise my 3 year warranty on the battery....

next step is ignition lock cylinder? and key replacement?
 

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05 CTS
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38 Posts
Re: New here ... Service Theft & key stuck even AFTER replacing ECU/ECM and key relea

It sounds like it could be the Internal Mode Switch in the trans. Is the indicator light on the trans lit up next to Park when the key is on and the car is in park? When my internal mode switch went bad, I did not have the key issue, but the ECM/TCM would indicate that the selector was in between gears instead of in drive and it caused all sorts of crazy issues.

The trans would not shift at WOT, because the ECM would kick in the rev limiter thinking the car was not in drive when it was actually in drive.

Have you checked the TCM for codes or just the ECM?
 

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2007 Cadillac CTS 2.8L
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Discussion Starter #6
Re: New here ... Service Theft & key stuck even AFTER replacing ECU/ECM and key relea

UPDATE: AUGUST 20TH 2015

Just want to update those who been having the same issue...

so i ordered the ECM from allcomputerresources on ebay...

since january i've been losing my head going back and forth with this thing...took the whole car apart and checked literally everything..

in the end my mechanic came across a junk CTS and tried the ECM off that...it released the key and then had it reprogrammed to my vin while on the vehicle..


so it was a faulty ECM AGAIN from those guys on eBay...be careful when buying from them...
 
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