Ok, when I talk about “rear ECM” I’m talking about the ECM that is in the trunk “boot” behind the fuel door. I’m just about to give up on this car, it’s a 2004 XJ8. I’ve had this problem since the beginning of the year when the cars rear ECM went bad and the reverse lights wouldn’t work as well as the power windows. I replaced the ECM and everything works except the car won’t start. I’ve been told that I have to program that ECM to work with this car since it needs to communicate with the other systems in the car and the immobilizer. Now, I purchased the Mongoose plugin and I’ve downloaded various versions of the SDD Programing starting with version 1.30. No matter what I do, I can’t get the SDD programing to read or write to the rear ECM, it just tells me that the rear ECM has blocked access to the program. Everywhere I’ve read that reprogramming this particular ECM is a piece of cake and super simple. I’ve worked on this every weekend for the past 3 months and still haven’t been able to do anything with the vehicle. I took it to a shop and they ended frying the ECM so I purchased 3 more ECM and all 3 give me the same results. It won’t grant the SDD software access. I’m pulling my hair here with this. I really need someone that has knowledge of this particular topic to please shine some light on this since I’m just about to give up and sell the car to a junkyard or something. With the passing of the days I grow angrier at the car and don’t want to do something I’ll later regret. I’ve attached a picture of the rear ECM so that the readers can know what ECM I’m talking about. I have an aftermarket radio in the car, I’m going to install the factory radio this weekend since I had a crazy dream that the factory radio needed to be installed for the SDD software to communicate with the ECM..... Dream.... more like a nightmare. At this point I’m willing to try anything.

 

Do you have a legit copy of IDS? Legit reader? (Mongoose) if you cannot answer yes to both then I'd find someone that has legit Jaguar diagnostics as you can do further damage.

Proceed cautiously!