I have a 2006 Jaguar XJR with 171XXX miles on it. I drove the car the previous day, but when I got in it next morning I had numerous codes and could not turn over the car to start. A 3 year old Exide battery was reading 11.90 vdc. Since the X350 cars are sensitive to voltage, I installed a Bosch battery reading 12.8 vdc.

I still had the problem. ECM was removed and inspected for water damage (7" of rain a few days before) but did not find any evidence of water staining. I sent the ECM to G7 Computers who found that a resister on the circuit board had failed. I reinstalled it after receiving it back, but still had the same problem. G7 agreed to look at it again, but did not find any new issues.

I have been looking for a used ECM, but consensus on the forum is that it would need to be flashed prior to installation.

My quwstion is whether the ECM can be flashed by a dealer or shop with appropriate software before I reinstall it in the car, or must flashing be done with the ECM inslalled in the car, which will require towing the car to the closest dealer an hour away.

 

Flashing must be done with the replacement ECM installed in the car and with legit Jaguar software/hardware.

I hope that's your issue but I still think your original ECM is not suspect. Sounds like a grounding issue somewhere on the vehicle.

Nonetheless, good luck.

PS - Make sure you find a replacement ECM from a XJR, no other vehicle line. (STR, XKR) and you may find the Jaguar dealer reluctant to reflash the ECM. They might want to install a new one, which would cost a small fortune! Plus labor

 

One of two modules in spare tire well on left side

Second module in spare tire well on left rear corner

Rear Electronic Module In Right side of trunk (boot) behind carpet. Note the two ground studs

Main Electrical Connector in front of ECM

Second half of Main Electrical Connector

One of two studs for negative battery cable

Ground stud for the two modules left rear of spare tire well
ECM received back on Friday. G7 says "A pin-out test was performed and there were no faults found with the computer you sent here to be repaired. It is possible that there is an intermittent fault occurring and could not be detected while it was here. Your computer …"

I installed it again and all the faults are still there. I located the Rear Electronic Module and cleaned the connectors and pins as well as cleaning all ground studs. I also cleaned the main connector in front of the ECM connectors and cleaned the ECM connectors again.

Jag-Bits has a used ECM and can sell a new ECM.

I checked around in the Lafayette Louisiana area, and there are no shops that can reflash a Jag ECM.

 

Not sure where to look next. What I may have to do is load the car on a tilt bed and have it brought to the dealer in Baton Rouge to have the ECM reflashed. But there has not been a consensus whether the original flashing dat has been lost of corrupted.

I am open to suggestions about where to look next.

 

Reflashing solved the problems.

I found a shop about a half hour away that could reprogram the ECM. So, I loaded the car on a tilt bed tow truck and had it delivered to the shop.

Here is what they did according to the invoice:

"C/S re flash computer
Ran Diagnostic check to find no communication to TCM, ABS, GSM, ICP, HVAC, Check power supply and wiring to each modules and reset PCM & Inertia Switch"

Car ran well with no codes or warnings displaced. Total cost was $284.41.

I spoke with the technician hoping to get more specifics, but he did not want to reveal much.

It was kind of hard to argue with him considering the total cost being so low.

 

How did you trip the inertia switch?

 

+1 how did the inertia switch trip??

 

I don't think I did. I drove the car home on the afternoon before this started and parked it without incident. When I tried to start the car next morning all the codes were now there and the engine would not turn over. If inertia switch was actually tripped, it may have been when loading or unloading onto the tilt bed tow truck (?) to bring it to the shop.

What the invoice says is that the technician checked the wiring to the Inertia Switch. It does not say if it was tripped or not. I had talked with the technician about what he found was the cause, but he was very evasive, so I think he solved a loose connection somewhere, but was not sure himself which thing he looked at was the cause. I think that when G7 replaced the burned resister, that somehow resulted in the need to reflash the ECM. I also have no idea when the resister burned out in the ECM. Was it when the engine was shut off, or before? Would the ECM have still functioned with the resister burned with the engine running before it was shut off? G7 never specified which circuit the burned resister was in.

The sole take away from this is that reflashing the ECM and checking all connections resolved the problem.