OK guys the other day in my 2001 xk8 I had some errors pop up like asc not available and incorrect part installed and the yellow and red light stay on above the message lcd screen. Brake light as well as check engine light and abs light are on. So I jump the car off and it started after I reset the inhibitor on the side of the dash. It was weird though the shift lever wouldn't move from park and the tach wasn't working. I researched and it said battery is no good. I changed it and now it wont start at all. It cranks but wont run. I'm getting fuel but no spark. I have swapped ecus and still no luck. All the relays and fuses work good. Here is the interesting part. Once the key is out the throttle body sounds like it is still engaged and I hear the fuel pump. If I unplug the relay for the ecu and plug it back in it clicks on and the ecu fan goes on and I can plug in my obd reader and read codes. THE KEY IS OUT THOUGH!! The codes are p1637, p1000, p1111, p1647, p1230, p1746. That is on both ecus that the codes pull up. I have a generic obd reader and once I clear the codes it comes right back on either ecu. I'm starting to think battery(even though its new!!) Or crank sensor. Car ecu stays on as well as tb engages and fuel pump on when key is out but no lights on dash pop up and it drains the battery. The car ran before I put the new battery when i jumped it. Any ideas???

 

There is a little flap that closes when the key is removed. That may be stuck. Try some lock lube or graphite to free that and see what happens.

Also note that it may not start because you swapped ECU's, and if you did so without disconnecting the battery first you may have damaged it

 

Battery was removed. It does it woth both ecus. And where is this flapped located? Any other ideas?

 

I'm thinking not just the flap as you have too much activity with the key out, but I'd be having a good look at the ignition switch to check it's working properly.
The flap covers the ignition key hole when you take the key out.
Also don't forget to post your intro in the new members section.

 

Yes but what else could it be! This all happened after the new battery was put in!

 

Was the other car running when you jumped the XK8? That is known to sometimes damage various electronic modules.

 

Yes but it ran when I jumped. Then I turned it off and cut it back on. Then I turned it off and swapped batteries from advance auto parts.

 

You could have more than one problem.

This thread might give some hints: https://www.jaguarforums.com/forum/x...ng-key-133276/

The relay that drives the ECU has a switched GROUND through the ignition switch. You could have a bad ignition switch, but perhaps more likely that wire is getting shorted to ground somewhere.

Have you had a lot of rain in your area lately? The short could also be through an electronic module that has failed due to the voltage regulation problems that occur when jump starting using a running car.

 

Car is garaged. And how can it ground out after the battery change? This wasn't and issue before battery change. And even if it is ground why won't it spark? It cranks all day and it ran before battery replacement? It getting fuel and all the other things except spark. I will say the codes that came up after the battery change are the same as before but u was told it was becuase of the voltage drop. All fuses check and relays check good.

 

This kind of problem is difficult to solve remotely, but if it was me I would unplug various modules one at a time as well as the ignition switch and see if the Ecu fan goes off. I would start with the BCM and the main instrument cluster as most likely to cause this kind of issue.

Your battery is draining rapidly so if you do this yourself you may need a charger or low battery will complicate the situation further.

 

Ok but the other issue is why won't it start? Even with the battery issue it should start? Shouldn't it?

 

The way it appears, the ignition is never really going off. This may be preventing the logic from invoking the starter. The starter is computer enabled on this car, so it needs to see the correct conditions to work.

 

The starter engages it cranks all day but won't run all the lights are on but no one is home so to speak.

 

OK, but even so, there is a short to ground somewhere in the ignition circuit if the car will not shut off. This is not just a case of a component drawing too much current with the ignition off. This may be affecting the logic circuits or may actually lead you to the cause of the no spark situation if there is a faulty module with an internal ground short.

You can better understand if you study the power and ignition circuitry here: http://jagrepair.com/images/AutoRepa.../jagxk2001.pdf , in particular how the relay which powers the ECU is switched by a ground switching that is part of the the ignition switch. Either a faulty ignition switch or another module connected to that same switched ground, or a chafed wire or excessive moisture somewhere is providing this ground path.

 

Car ran before new battery though nothing changed?

 

You jumped it from a running car....that damages electronics because the voltage does not regulate properly....possible even one time and even if it ran initially.

 

But after I jumped I let it run and I turned it off and cut it back on! With out cables..

 

It's pretty obvious that something is wrong now.
I doubt anybody on the the forum is going to put their finger right on it, so maybe it's time to start checking out some of the suggestions already made?

 

My best armchair guess based on the circumstances you described is a module fried (most likely the BCM or instrument cluster), or the ignition switch contacts were overloaded and damaged, or a wire melted and shorted to the chassis.

The advice is worth what you pay for it That is all I can say now....you are free to do what you want.

 

So swap out bcm?