Chrysler Repair: Anti theft alarm: 04 Crossfire, drb iii, body control module

Question
QUESTION: Hi,

I had been getting the alarm on my 04 crossfire going off falsely for a month.  Took it into the dealership and they checked the door and hatch sensors, and then disconnected the siren.  After which, the car would not start.  They tried to communicate with the PCM, but could not connect with it.  They claim the PCM is broken, and they need a new one, at $2500.  When installed, they may not even know if the alarm is fixed or not.

My question is, do you feel they possibly bungled the repair, could the PCM just go like that (car was running fine when I brought it into dealership). When checking the door and hatch sensors for the alarm, what do they plug their tester into to see if they are working?

Thanks for any help

Steve

ANSWER: Hi Steve,
Fortunately I do have the Crossfire manual on a CD. Without knowing what they did I can't say whether they bungled the repair. The vehicle has a theft security module located in the trunk which is connected to the door sensors. That module is then connected by a digital communication circuit to the body control module which in turn is connected digitally to the pcm which has to get the OK from the bcm to operate the engine electronic (spark and fuel pump).
They should have used a Diagnostic Readout Box III to evaluate these systems to tell them what is wrong and that should in no way damage the pcm.
I would question that the pcm is the problem if they used the DRB III only. I would ask them to show you the that they have a code number showing on the DRB III that says the pcm is damaged and must be replaced (ask to see that "live", so that you can verify the specific code number(s) that shows up on the screen of the reader). Then let me know that number and we'll see what the possible reasons for it are as shown in the manual.
By disconnecting the siren they probably have modified the security system by putting it into a  'hard lockdown' (a built-in self-defense against thieves who try to defeat the system by tinkering with it) and so they now need to clear that situation using the DRB III so that the bcm will then give the OK to the pcm to start the engine again. They may well be mistaking this hard lockdown situation for a failed pcm!
I would not pay them anything until you get this information and have an opportunity to check it out. You may have to contact Chrysler Corp regional service for help in dealing with the dealership. I wonder if they are just lost and are trying to throw parts at the problem at your expense. It has the 'smell' of a bungled job.
Please let me know how this works out.

Please read the PS below and respond.
Thanks,
Roland

---------- FOLLOW-UP ----------

QUESTION: thanks very much for the response.i have not had a chance to ask the dealership these questions yet.  but i have a follow up question.  where does the drbIII plug into?  does it plug into the PCM.  they are saying the PCM will not communicate with their equipment and thus is not re programable (cant get the car out of lock down mode is my guess)and thus not working. when testing for the door and hatch sensors, are they pluging the tester into the pcm, or the trunk mounted module? i ask, because they claim they checked the sensors, and thus knew the door sensors were ok.  but if they got that info from the pcm, then i know it was working before they fooled around with the car.
they claim the pcm can go at anytime, and it just went while at the dealership.

PS: i called chrysler, and they claim they do not get involved in workmanship issues.

Answer
Hi Steve,
The DRB III plugs into the data link connector under the dash and the link commector is supposed to power the DRB III on its pin 16 that comes from fuse 14 in underhood accessory fuse block.
The PCM gets power two ways: all the time from engine control fuse 1 located in the relay control module,  and when the ignition is 'on' from fuse 9 in the underhood accesory fuse block.
I would suggest that all three fuses be checked to be sure that the DRB and pcm are powered up appropriately.
I think you are correct that the pcm was probably working if the DRB worked to tell them about the door sensors to begin with. It could be that one of the two data wires from the data link to the pcm may have been become broken.
Does the DRB work now? If so, what is it saying about the situation? Does it say the pcm will 'not communicate' (which it should say if that is true) and what code number is that?
I don't believe the pcm 'went' on its own accord while at the dealership.
Thanks for the rating/nomination. Up to 5 such nominations 'count' so keep going if you think I deserve it.
Roland