Help! ECU problems!

(terence pattison) #1

Hi, guys,

A while ago, I had a problem with my '96 XK8 - it seemed to only be firing on 4 cylinders. My mechanic told me he thought it was the coils, so I bought a complete set of coils.
He fitted them, but the car still only barely moved in ‘limp’ mode. He then explored further, and now tells me that one of the ECU units has been damaged.
He has sent the unit off to somewhere in England to see if it can be repaired.
If the word comes back that it cannot be repaired, what are my options? I don’t even know what the ECU does!


Terry Pattison

(Neil Bennett. Patron) #2

Pretty much everything as it is the main brain of the car and it interacts with all the other Modules and their functions!
Hopefully your Indy has made a note of the Part No. and the Suffixes on yours, I’d check on Ebay or the like for a guarenteed used salvaged ECU with the same numbers on it.
It could be the quickest and cheapest route.

(Eric Capron) #3


The ECU (Jaguar calls it Engine Control Module , ECM) does exactly that. It takes inputs from many sensors and adjusts the fuelling and ignition timing dynamically so that the engine runs correctly under all operating conditions. If yours cannot be repaired (and there are several specialists in the US who seem to be able to repair these) you will have to find another one from a car that has been scrapped.
ECMs are programmed to match the update status of the car the other modules that it communicates with so it is important to get one with the same number. If you still have the module, the number is on the label and the last two letters are especially important because these describe the version. If you do not have it, if you look in the boot, on the inside of the back panel of the car, there should be a list of all the modules fitted to your car and the revision numbers.
The ECM itself is located under the bonnet on the passenger side of the vehicle towards the firewall. It is under a cover which is fixed with tamper proof screws. Also under this cover you’ll find the transmission control module.
Shropshire, UK

(terence pattison) #4

Thanks for the advice, guys!

(Eric Capron) #5

If you know someone who is good at electronics, before you buy another ECM get them to have a look at this thread.

As it happens, the problem with mine was something else but it is reported to be quite a common fault with the early Denso ECMs and provided not too much damage has been done, relatively cheaply fixable. It depends how badly damaged the printed circuit board is.