Good luck with this but better get it checked out by sdd machine keep us updated

 

Back in 2016 I went over to Costa Rica for six weeks, leaving my car with a friend in Ft. Lauderdale who promised to give it a drive once a week or so. When I returned, I started the car without any problem and drove it for about 20 minutes just to top up the charge on the battery. The next day it was dead as a doornail. Jumped it with with my friend's biga$$ Cadillac, albeit with a bit of difficulty (had to rev the Caddy high and hold it for a couple minutes to build some charge on the Jag's battery before it would turn over), then drove it to the Jaguar dealership where a courteous and friendly service manager told me he could pull it in and check it out for $80, but more likely the battery needed replacing. He mentioned that the 2007 XK has a daily 3.7 amp draw which will discharge the battery if the car is left to sit for long periods. It might start okay one day and then be dead the next, just as I had experienced.
My friend owned up to only having driven the car once in the six weeks I was away. Battery was 6 mos. old and under warranty, so a visit to the local Auto Zone found the Pennsylvania purchase record. Modern batteries can suffer from subsequent cell failure problems if they are fully discharged, as mine was. A few minutes discussion yielded a no-questions-asked brand new replacement battery, which they installed for me straightaway. I was cautioned to drive it at about 40mph for a full half hour to ensure topping up the charge ... the first 15-20 minutes to replace the power draw from just a single start, the rest of the time to finish the topping up.
Moral is not to let the car sit for long periods, but drive it at speed weekly for 20-30 minutes to keep the battery in good charge. If you must let it sit, get a trickle charge device.
As a veteran of several decades driving a couple Austin Healey 3000s, I always enjoyed the simplicity of the battery turnoff switch in the trunk. I shut the Jaguar down for one winter storage period by simply disconnecting the battery cables, then reconnecting them several months later. All systems reset at that time, so it was a bit of a learning experience.

 

You either misheard him or he needs to go back and check his documentation because the sleeping draw is 30mA not 3700mA.

 

I wanted to update you on my saga. Sadly it's not cured yet. :-(

But a very nice member of this forum dropped by and spent several hours with me and an IDS system on my XK. (we even swapped batteries from his XJ as a desperate solution).

Bottom line is I appear to have 2 (unlinked?) issues:

According to IDS my ECM has communication errors (which do not clear)
I also appear to have a significant drain on the battery upon turning the ignition on (whether known good battery or my suspect battery - the drain is huge enough to knock a battery to less than 50% charge after having the ignition on a couple of times, and 2 failed attempts to start (don't even get to cranking at the moment)

I suspect that both issues are now related and have just taken the plunge into a replacement ECU and am working through all the basics, full earth check, underbody rodent damage inspection, revisiting anything i touched before and making sure all is good.

I'll keep you looped to my progress if i manage to nail the issue.

 

Could it be a locked up starter motor? If damaged internally, could cause a heavy qwik drain.

 

Potentially but this drain occurs as soon as the ignition button is pushed ie foot off the brake and before cranking initiated.

 

I'll defer to the written specs and plead guilty to having misheard him, though "3-point-7 amps" resounded at the time and continues to resonate in my memory. I parotted it back to him and he confirmed it at the time.

 

Sounds like the alternator.

 

IDS points to an ECM comm failure. I cannot even get to cranking where an alternator issue would be able to be diagnosed.

 

Okay, I had similar issue, probably not the same, where it started out with a mass of codes, hard to start. Put it on charger drove it and car died after I stopped for an errand. Got jump and drove it home, got codes again along with alert and warnings. On the charger overnight, same routine for several days. By the end of the week, It was dying after driving short distances, then refused jump, charge. went to the dealer, I had made appt earlier in the week. after a week of testing three things were found; alternator was not charging the battery, battery was aged and not holding any charge and there was a black cable with a box on it coming off the battery that needed replacement. New alternator, battery and cable. Has not happened since, 2 years. But you could be right about it being the ECM everything has to run through that. the black cable w/box goes to the ECM.

 

That black box off the battery, was it on the left-hand side of the battery cradle - the "mega fuse", by any chance?

 

I figure that Black Box is the Battery Monitor Unit. Dude's car is a 2014.

 

I wanted to keep the thread updated:

With the help of 6rotors and a JDS system we have confirmed ECM as the issue. Posting the JDS screens for insights/reference.

Next step is to remove the ECM and do the pin check diagnosis for the HS CAN bus...

 

I will have to look again, but I believe it was on the left side, the black negative cable.

 

.......... which is why I said it is probably the Battery Monitor box........

 

Further update:

Using SDD to guide diagnostics I have confirmed that all pin out voltages and resistances are where they should be. The wiring loom appears to be intact.

ECM has been removed and when the replacement arrives I’ll be reprogramming and will update.

Of note, with the old ECM disconnected, my battery drain is negligible over several hours - an indication of some component failure in the ECM I suspect.

I will update mid September as I go down the journey to replace and reprogram the ECM. It’s currently stuck in Erlanger, Kentucky on its way to Ontario :-)

 

Put your old ECM back in. When you change out modules using SDD you need to start/ follow the process with the original one in place.

 

I do believe his previous session said "Cannot connect to ECM" or something like that. I'm too lazy to look back right now.

 

Thanks CeeJay. I thought I read that too. Really just wanted to stop him from installing a replacement before firing up SDD. Best way to remember is to plug the old one in.

 

thanks guys, plan was to follow SDD through and through, pretty much as you’ve said. Always good to have a second and third set of eyes, though :-). Thanks!