Someone connected battery in reverse polarity for a moment and blew my engine ECU for my '95 XJR.

Any advice on repair? Could I get a replacement XJ6 and swap the eprom's? Good ECU repair place I could send it?

Any advice would be greatly appreciated.

 

How do you know the ECU is damaged?

If you take the EPROMs out and fit them to another ECU from an XJRyou will have to orientate the lambda ensors and adapt the closed throttle voltage. This will require workshop diagnostic equipmewnt like WDS, IDS our a more generic tool like Autologic. The EPROMs contain multiple different calibrations. The correct one is selected during end-of-line programming in the factory. This step will be missed if you change the EPROMs in an ECU. The default calibration may not be the same as the one that was selected during the end of line programming, but the car will still probably run OK, as all the calibrations will be for the XJR6 model.

 

AS PER TSB 05.1-26am5 (T493) the 1995MY XJR PROMS were NOT replaced and only the throttle spring was to be replaced.

Note: On 1995 MY XJR vehicles not previously reworked under
R493, the only repair to be performed under T493 is to replace the
throttle spring.

ALL other ECMs were updated with new PROMS

Vehicle---------VIN RANGE-------- KIT #-----ECM part #--(PROM ID)
95 MY XJ------- 720120 - 754303 LNC 1411AB LNA 1410AL (9361)
96 MY XJ - SWB 754304 - 787953 LNC 1411CA LNA 1410VK (9357)
96 MY XJ - LWB 754304 - 787953 LNC 1411DA LNA 1410DF (9358)
96 MY XJR------ 754304 - 787953 LNC 1411EA LNA 1410SF(9359)
97 MY XJ - SWB 787954 - 812255 LNC 1411GA LNB 1410AE (9353)
97 MY XJ - LWB 787954 - 812255 LNC 1411HA LNB 1410FE (9354)
97 MY XJR------ 787954 - 812255 LNC 1411JA LNB 1410DD (9355)

Years ago a customer bought a 1995-1997 XJR at an auction and brought it to the dealer for poor running and I finally diagnosed it as having the wrong ECM installed. They bought a used one from a salvage yard and that cured the poor running.

You might just need to install the supercharged PROM set into a known good AJ16 ECM.

I don't know if this recall was JUST FOR THE U.S. or for more markets.

bob gauff

 

Main reason I suspected the ECU is that I can no longer use my ODBII tool.

Also, the car does not start. Turning ignition key, nothing happens, not even a click.

I found a 4.0 (N.A) ECU on Ebay, will try that and post results.

 

How about the interior lights?? Do they not come on either?? If that's the case, what you describe sounds like the Central Microprocessor, some call it the body computer. ECM replacement won't help you there.

Also need to do the basics, powers & grounds.

Good luck!

 

The radiator fan comes on when turning the key, as do the dash lights, and the seat works, usual noises etc. I don't recall if the other interior lights come on, I will have to check when this rain stops!

 

New ECM arrived, now have comm with my OBDII (Torque), which I didn't before. However, I think also, both the body processor and TCM got hit by the reverse polarity.

The break does not release the gear shifter, interior lights don't seem to work properly. Still no start, and transmission fault light stay on!

Any more thoughts?

 

Hmmmm! Sure sounds like the body processor took a hit. If so, that's the next thing to attack. See if the turn signals, flashers and wipers are also inoperative like the interior lights. If they are, that pretty well seals it the BPM is dead. Ouch! That item does so much, I don't think I'd worry about anything else 'till its fixed.

Don't forget the powers & grounds and check all fuses.

Good luck!

 

Replaced the body processor, now lights work, can move gear out of park, but still will not start. All fuses OK, grounds good so far as I can tell.

Pretty much ready to give up on the old girl...

 

Don't give up. I've got confidence in these guys.

 

Gave up and will part out the XJR. Purchased an '03 XJ8 today