Jaguar Repair Problems? Ask a Jaguar Repairs Expert.
Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.The problem you are describing is in most cases caused by a failing alternator but before you replace any parts the first thing you need to do is to have the system scanned to retrieve the fault code that should be setting when the battery light comes on. If you can get this done and post back with this I will direct you from there as to the correct repair.
The code P1146 indicates you have Low input from the Engine control module (ECM) on the voltage regulator request signal wire, in order to determine what is failing you are going to need to do some testing. I have enclosed the test in the link below. You will need to start your testing at pinpoint test B1.https://dl.dropboxusercontent.com/u/104923897/Pinpoint%20test%20B%20Jul%2018.pdf
If you sure it is the ECM you are going to need a dealer scan tool as well as access to there software to do this programming. In most cases this is done by the dealer.
The common cause for this code is usually a failed ECM as you suspect providing you dis your testing correctly and the wiring from the ECM to the new alternator check okay . There no need to redo the steps if you have done so already. Thank you as well. Please take a moment to rate my service so I can get credit for my time, the question remains open for follow up even after doing so, all you need to do is return to this question if need be.Thank you again.