2005 Cadillac CTS theft system

Asked by GuruV9MGY Aug 01, 2018 at 10:33 PM about the 2005 Cadillac CTS 3.6L RWD

Question type: Maintenance & Repair

Hello,  I have a 2005 Cadillac CTS, and the key is
stuck in the ignition, the engine won’t crank, there is
a red light in the mirror. After the key is turned to
“on” for about a minute, the “ service theft system “
shows up on the screen. I am able to remove the
key with the release button under the steering wheel
though. We were in the middle of installing new
door speakers, when our n ugh or walked over and
asked for a ride to pick up vehicle, the car had
turned into theft mode once we started it. But on
the way back, we realized the fuel pump had been
turned off as well, later on now after several
attempts to fixing it, it won’t even start. Please help,
and thank you

7 Answers


Our Cadillac is also a 2005 CTS and had the same problem besides all of the gauges stopped working when the service theft system came on and the key got locked. We took it to the shop who charged us 389.00 to remove the key and fix the anti-theft and got told the Brain box went bad and it will cost over 1,200 to fix to get the gauges working. BTW our car has only got 90k miles. so this sucks pretty bad.

11 people found this helpful.

your brain box is a ecm i have a 05 cts 3.6 second keys r not hard to get out there is a release. under the steering wheel, only way fix the theft is to pull the fuse for it unless you fix the bad module ie brain=ecm

4 people found this helpful.

got my ecm on ebay programmed for 200 but u can pay 359 for a lifetime warranty takes 15 mins to put in 2 connectors and 4 bolts dealers scam u and shops scam you on ecm install only thing either is good for is diagnosis

7 people found this helpful.

I can fix it, it's too hard to walk u thru it. I worked for Cadillac for years. I can reprogram it! How far away r u?

8 people found this helpful.

I am having the same problem with my 05 caddy cts can you please tell me what to do? Thanks so much Melissa

3 people found this helpful.

Im having the same issue with my 05 CTS theft mode went off after I pulled the fuse but car still wont start its not reading that it is in park the only way it starts is if my gear shift is illuminated on park?! smh dont know how to fix that any help??

2 people found this helpful.

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