99 XJ8 , I bought this car cheap as it would not start , Changed the Fuel pump and the car runs fine But I have : Fail safe engine mode , Check eng. ,Amber light on , ABS light on , Brake light on ,Incorrect part Fitted and Trans Fault , I have 3 Parts cars , engine runs good , Tranny in Fail safe mode

The Gauges do not work either , Codes are P1642 and P1647 I have read all I can find on those codes , Using Cheap Scanner that will clear the codes

I have tried changing the Trans Controller , Body module, Originals are back in , Inertia Switch ,Both Diodes in trunk swapped all the relays around and Instrument cluster with the wrong programming code re-setting the battery power on each change ,,, Nothing Changed

My buddy who was helping me turned on the ignition and was touching the battery cable to listen to the fuel pump , he did this several times so he told me I suspect this caused the Problem , I do not have the correct engine ECU to test that module

I feel something should have changed but Oblivious I am missing something
Please Help Me before I pull out what little hair I have left :-)

 

To more easily diagnose the CAN bus fault you really need to read the DTCs from ALL the modules on the network.

You might have a module that has lost communication or is faulty and preventing communication.

You will need a more complex diagnostic device than a simple OBDII reader.

DO NOT SWAP ECMs without performing an 'immobilization-setup' with an advanced diagnostic tool. The replacement ECM will probably not work until it has been configured to the network.

Network faults can be difficult to diagnose.

'Touching' the battery repeatedly is NOT a good thing. You should make a 'quick and sure' connection when the battery cable is attached. Many electronic things can be damaged by on-off-on-off-on battery cable attachment and sparks etc.

Jaguar recommends a 'QUICK AND CLEAN' connection.

This is from TSB 414-01am

"Always disconnect the battery negative cable before disconnecting or reconnecting any control
module. Disconnect the negative cable first and reconnect it last. After disconnecting either or
both of the vehicle battery cables, wait at least 30 seconds before reconnecting the last cable.
Always make a “clean” final connection. If the cable makes momentary contact only, wait
another 30 seconds before trying again."

You may have damaged some components.

bob gauff

 

I agree Completely about the Battery Connect But my Friend definitely did it several times , Thank You , I have no Idea where to go next , I can get another ECM with exact part # off ebay but would it help ? About to sell it for Parts as I am so Frustrated :-) my buddies 5k snap on tool would not read it , would not pull up the VIN it is the newest and the best reader snap on offers

 

If you replace the ECM (X308/X100) you will likely need it configured to the network. Whenever I swap out an ECM I have to perform an 'IMOBILIZATION-SETUP' or the engine just cranks and will not start.

bob gauff

 

Hi!
I had the same issues. I changed the battery earth (Ground) strap & the engine earth strap. Additionally, I changed the inertia switch (Under wing). So far, it's worked. The earth straps are cheap and worth a try.