I just want to make sure I understand the SKREEM process. Ok , the key itself is just mechanical and turns the ignition switch. The RFD chip in the fob communicates with the SKREEM module behind the instrument panel through the antenna ring around the ignition. If the RFD chip has the same code as the chip in the SKREEM , it sends the code to the ECU. If the code is the same as on the chip in the ECU then it will allow the car to start. Is that about right, or am I missing something?

 

I do not think the ECU has a coded chip, it just receives the go ahead from the SKREEM.
But, as always, I could be mistaken.

 

Hi Maggy, I think you've got it right (and ala_xfire is also sort of right). The SKREEM module (or immobilizer) looks at a serial number coded into the ECU, and if it matches the one it has stored, it lets the ECU start the car. That is the immobilizer and the ECU are coded together, unless they match then the ECU will not start the car. All the other stuff about the key fob and SKREEM is correct.

I've included a screenshot of an ECU that doesn't match the immobilizer. As you can see the immobilizer is preventing the ECU from starting the car because the Serial Number (displayed) stored in the ECU does not match.




DAS Drive Authorization

 

My info (Student Reference Book) says the SKREEM checks the valid key info stored in the PCM and if it checks out the car will run.