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Service Theft & key stuck even AFTER replacing ECU/ECM and key relearn

31K views 51 replies 9 participants last post by  sonic1000 
#1 · (Edited by Moderator)
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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#3 ·
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.
 
#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?
 
#5 ·
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?
 
#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...
 
#7 ·
Hi guys,

I've searched the forum to find out why my 06 CTS won't start, and it seems that replacing the ECM works for everyone else.

I replaced the ECM with one programmed for my VIN, performed the 30-minute key relearn, and the car cranked right up.

However, the next day, it wouldn't start, and I had to jump it at the Starter Relay with a paperclip. It started fine the next time. Is there something else causing this that I'm missing?

Thanks in advance.
 
#35 ·
Hi guys,

I've searched the forum to find out why my 06 CTS won't start, and it seems that replacing the ECM works for everyone else.

I replaced the ECM with one programmed for my VIN, performed the 30-minute key relearn, and the car cranked right up.

However, the next day, it wouldn't start, and I had to jump it at the Starter Relay with a paperclip. It started fine the next time. Is there something else causing this that I'm missing?

Thanks in advance.
I've got a 2007 CTS that I had to replace the ECM on. After the swap, I couldn't relearn the key no matter how many times I tried. Is your 2006 CTS using the Passkey 2 or 3+ security system? I'm so desperate to figure out how to start the engine.
 
#9 ·
"I've searched the forum to find out why my 06 CTS won't start, and it seems that replacing the ECM works for everyone else.

I replaced the ECM with one programmed for my VIN, performed the 30-minute key relearn, and the car cranked right up. "

This is an excellent cautionary tale that reaffirms the herd mentality rarely works when it comes to troubleshooting a car remotely.

Your problem may be as simple as a starter relay, starter, battery, etc. Throwing parts at a problem blindly usually results in the same symptoms, with the only change being an empty wallet. If you don't know how to troubleshoot, pay someone who does. You'll be money and time ahead.

CCC
 
#10 ·
And you are an excellent example of someone who doesn't read posts thoroughly, trolling the board, waiting to chastize someone you don't know who is just looking for some help.

The car starts when the starter relay (which is in working order) is bypassed, so it follows that neither the starter relay, the starter, nor the battery are the problem. Rather, most likely one of the control modules has picked up an error that is preventing the activation of the starter relay.

Clarence9777, on my 3.6L the ECM is located on the front passenger side of the engine, next to the throttle body. It's very easy to swap.
 
#13 ·
It needs to be an enhanced OBDII code reader that can the read other codes besides "P" codes, specifically "U" codes in this case would be helpful. If you're not in Cali, you can go to a parts store like Autozone and they can read them. Just be sure to ask them to use a scanner that can read P, B, C, and U codes. I'm betting you have a U code or two at least and maybe others. Be sure to write them down.

Bill
 
#14 ·
Thanks Bill. I will do that today.

I do keep getting "Service Vehicle Soon" on my display. Is this something I can take care of without having to go to the Dealership or is a Tech II the only thing that will take care of it?

On a side note, I stopped using my 10-year old master key and have been using brand-new keys. The problem has not reoccurred. Is it possible for the RFID transponder in a key to begin to fail intermittently?

Thanks again.

----------

It needs to be an enhanced OBDII code reader that can the read other codes besides "P" codes, specifically "U" codes
Bill, could you point me to such a code reader? I'm searching Enhanced OBDII readers, but the descriptions aren't explicit enough for me to tell if they read everything (P, B, C, U). I'd like to get the best short of a Tech II.

Thanks!
 
#17 · (Edited)
You'll want to get a scanner that can read OBDII/ABS/SRS(Airbag) codes. That should have you covered.

I have a Tech2 but here is one that is made by SPX, the company that makes the Tech2: https://actron.com/content/autoscanner-plus-codeconnect-abs-and-airbag-coverage Amazon has a pretty good price on it: http://www.amazon.com/Actron-CP9680...ie=UTF8&qid=1456360006&sr=1-1&keywords=CP9680 This scanner will work with cars at least through 2013.

B0100 refers to an air bag sensor that didn't ID itself quick enough after power up. The other two are likely the result of the B0100. This very well could be just a communication glitch. Best bet at this point is to reset the codes and see if they come back. If they do come back I would try repeating clearing the codes a few more times. Usually it clears up on it's own as the codes all have a communication theme. If that doesn't work then we'll have to track down exactly where communication is breaking down.

The place that read your codes can also clear them, if they're nice people.

Bill
 
#19 ·
The place that read your codes can also clear them, if they're nice people.

Bill
The girl at O'Reilley's read my codes but I had to show her how to delete them. Does this device you liked to have similar functionality as the Tech II? I ask because I need a Tech II (or equivalent) to tell my radio that it is in a CTS to restore the option for me to program my steering wheel keys. I'm considering buying a Chinese-made one.
 
#20 ·
The device I mentioned does not have programming functionality, if you want that it's available with many different units but it's gonna cost ya ...a bunch. A Chinese clone of a Tech2 is a crap shoot at best. Better off having a dealer doing the programming then paying the extra money for the functionality unless it's something you feel you'll be doing routinely, in my view.

Also, while with your 2006, there are modules that have the info for the Tech2 to function, for my 2014 CTS and some of my other cars, I have to buy a subscription that allows me to connect to TIS2Web for it to function...not cheap either modules or subscription. Bottom line is that the Tech2 is great but it's a lot of money new(I got lucky and picked mine up for $1500 used from a Corvette guy I knew that needed the money) and the modules set you back close to a grand each new. Over the 15 years I've had it, I like to think it's paid for itself but that may be wishful thinking.

Bill
 
#21 ·
Thanks for the insight. Do you think it's strange that this remanufactured ECM suddenly allowed me to crank without having to learn the keys?

----------

Got a new code today, P0615 Starter Relay Control Circuit, and had to jump start at the relay. GM tells me that I need a new Passlock Sensor (Ignition Cylinder) for $550. What do you think?

Also, what are your thoughts on this product: http://www.vxdiag.com/wholesale/vxdiag-vcx-nano-for-gm-opel-wifi-version.html

Supposedly, for $119, this device will let me communicate with my car through the Tech2Win interface, although I would still have to purchase a subscription to the software.

Thanks!
 
#23 ·
Has the dealer done any diagnostic work that led them to think it's the ignition switch? Do they know you have a recently programmed ECM?

In view of the fact that you replaced the ECM, I think the problem likely lies in the ECM security programming. It's not unheard of for the ECM needing the security programming repeated. I heard of some instances where it took three time to finally succeed.

As far as the vxdiag goes, I know nothing about it.

Bill
 
#26 ·
trying to relearn keys on a new computer and nothing is working! it was supposedly reprogrammed to my VIN as well. it will crank, start for 1 second then die. key is stuck in ignition and needs manually released.


things ive tried:

10 mins on "on" 10 seconds off x3 .

10mins 30 seconds on, 10 off x3 .

cranked then to on for 10 mins and 10 sec off

i have also tried hitting key release all the way back to full off where you can release the key, still no dice.


i want to get this damm thing up and running! help is much appreciated.


every time i do the relearn process is the security light supposed to flash off? when i start the security light goes away quick, but after 30 seconds of on it lights up. after 10 mins the light does not go off either like ive seen in other videos and posts.
 
#27 ·
mine runs fine, but my spare key isn't completely programmed. Sometimes it will start and display the service theft system message. Sometimes starting is disabled. I recently purchased a Tech 2 scanner but I am not clear on how to delete a key and add another. My car only came with one key and no remotes.


Did you call your local Stealership to get their input?
 
#28 ·
It would seem that the instructions weren’t followed exactly... here they are from this link. https://www.cadillacforums.com/foru...-2003/171547-thread-diy-mods.html#post1901882

The following should help both of y’all.
IF NO OTHER WORKING KEY FOR THE CAR IS AVAILABLE:

1. Put the newly cut Master key into the ignition and turn it to the ON (RUN) position. A "Security" indicator light on the dashboard will stay on for 10 minutes.

2. Within 1 minute after the indicator light goes off, turn the ignition to "OFF" then return to the ON (RUN) position. The indicator light again will stay on for 10 minutes. (DO NOT REMOVE THE KEY)

3. Again, within 1 minute after the indicator light goes off, turn the ignition to "OFF", then return to the ON (RUN) position. The indicator light again will stay on for 10 minutes. (DO NOT REMOVE THE KEY)

4. When the light goes off for the third time, the new key is programmed into the computer and will start the car. Remove the key and then re-insert it into the ignition lock and start the car.

All previously stored codes will be erased. To stop the process at any time, simply remove the key and use an existing key to start the car.

:: HOW TO PROGRAM THIS KEY IF YOU HAVE ATLEAST ONE WORKING KEY ::


FOR CARS WHERE YOU WANT TO JUST CREATE A SPARE KEY:

1. Place an already programmed key in the ignition.

2. Cycle the ignition from OFF to ON (RUN) to OFF.

3. Within 15 seconds, insert the new, properly cut Transponder key in the ignition. Turn the key to ON (RUN) or START. The "Security" indicator light will go on and off. Turn the key "OFF".

The key will now start the car. Repeat the second step for each new key to be programmed.


KOT
 
#31 ·
my car has the exact same problem. Did you manage to start the car after replacing the ECU that the Dealership called "bad"? Much appreciated.

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

UPDATE: AUGUST 20TH 2015

...

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...
I ordered my replacement ECM online and it came pre-programmed with the VIN of the vehicle. I've tried many times the key relearn procedure without any success. Does the replacement ECM have to be programmed while on the vehicle for it to work?
 
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