I thought I posted but can’t find it. So, forgive me if this is a repeat post.

My new to me ‘15 XKR ‘vert with 38,000 miles, has a random start issue. Occasionally when I go to start it, the accessory stuff comes on, but when pressing brake, it’s in park, and pressing start button…all I get are some weird noises in the engine compartment. There is no cranking of starter, nor even clicking of the starter solenoid.

My first thought was the main battery. So, I took it out, and took it to Batterys Plus where they tested it, and it passed with flying colors: 12.6 vdc, and 700 CRANK amps.

So, I took it back home, and reinstalled it. By the way, and twisting my recently surgically repaired knee in the process. After getting the battery installed, I decided to give starting a try again, and it fired right up. A few days of starting and stopping it never happened again…until a few days later. Tried to fire up the kitty, and same issue. Just for yucks I tested the voltage at the engine area fuse panel and it was a strong 12.5 volts…so no voltage loss from the battery. I decided to try the disconnect battery thing. So, I disconnected the negative cable, and jumped the negative cable to the positive cable, reconnected the negative cable…and the kitty fired up and happily purred. We went for a drive that had multiple starts and stops, and she fired up each time.

So, I mixed my self a nice and appropriste vodka martini, to help with my thinking. The one thing that was different that preceded not starting, was that I had been running the kitty in accessory mode trying to pair it to my garage door opener. And had even gotten a warning of low voltage in the infotainment screen, even though it wasn’t lower than 12.2 or 12.4 at the battery. Then had a Battery Tender connected. The observation of following extended accessory mode is not statistically significant, and I’ll refrain from running it in accessory mode…until I figure this out.

I had a friend hook up his OBD tool and we did a brain scan of the kitty, and found the following:

Intermittent: after clearing did not come back
U0140-00 Lost Communication With Body Control Module
U0155-00 Lost Communication With instrument cluster control module
U0156-00 Lost Communication With information center A
U3000-55 Control Module
U3000-87 Control Module
U0199-00 Lost communication with the door control module A

Permanent: (but not likely related)
B1A56-13 Antenna Circuit
U300D-14 Control Module output power A

And these after getting new tires and TPMS installed…
C1A56-31 front left tire pressure sensor and transmitter assembly
C1A58-31 front right tire pressure sensor and transmitter assembly
C1A60-31 rear left tire pressure sensor and transmitter assembly
C1A62-31 front right tire pressure sensor and transmitter assembly
C1D29-87 External receiver data line (intermittent)

Intermittent- I’ll replace key fob batteries..but haven’t done yet
B1B01-67 Key transponder
B1B01-87 Key transponder

Historic:
B1B33-86 Target identification transfer

Soooo, for those patient enough to read through this…any suggestions?

in the interim, I’m carrying a socket wrench with 10mm socket and jumper, to do a reset if it happens on the road. And I’m considering installing a negative side master switch to facilitate resetting if necessary.

 

I hate to say this, but regardless of all the tests you have made on your battery status, the only way you will be 100% certain is changing it with a new fresh and recently manufactured battery. Yes, it's a pain, but look at how much effort you have made so far? So many quirky issues arise from a defective battery, it can't hurt to have it replaced. Regardless, having a new battery on an XK is always a positive thing! If the problem still exists, your investment won't be that big, and you'll have a good starting point. Good luck and let us know how you make out.

 

I agree with the battery replacement when ever there are weird issues. But, this battery is 1 year old, and does test well, so I’m going to stick with it and see what happens.

I did just replace the key fob batteries today.. And I’m not going to run it in accessory mode, to see if it ever goes nuts again without following accessory mode.


It seems to me one of the confusers (a.k.a computer modules) is losing its mind. But, I don’t want to just start replacing stuff until I find a reproducible set of circumstances.

 

It does sound like battery issues - my truck battery would do stuff like that - then next minuter it would be okay - eventually the battery died - I suspect some internal issues between cell.

 

Try Pressing the brake Pedal Harder. Sorry about your knee.
Before starting, and or bleed/change the brake fluid, incase of air in the system, or water in the brake fluid.
If we are still taking about the difficult start scenario.
I am nearly done now of what we are talking about!

We have done the battery to death.

 

Ok, I am lost here…what is meant here by “accessory mode” and how do you run the XK in accessory mode? Do you mean turning the key to ACCESSORY but not running the engine? Wouldn’t that be “placing the car in accessory mode” or….? Just trying to figure the situation correctly,

 

The true test for a battery is to allow it to rest a minimum of 6 hours, following charging to 100%.
It should read at least 12.6v.

Secondly, as per the workshop manual, it is standard procedure to clear all codes when so many unrelated codes present themselves.

Think of BMS as a simple monitoring of the discharging of the battery. Once a threshold is reached, the generator’s charge is enabled via the rectifier to provide the charging current.

Don’t worry about charging the battery and not resetting the bms… over a few running cycles it learns the behaviors and resets appropriately.

Cheers.

 

My '09 XK has done the same thing as XKDreams' car, but only twice since I bought it seven months ago. I replaced the battery immediately after I bought it. The first time it happened it wouldn't start after multiple attempts, so I know I was pressing the brake pedal down hard enough. The second time was just the other day and it started on the second attempt. Limited sample size, but at this point it's happening about once every 80 + or - starts.
Regarding brake fluid, it had a brake fluid change/flush in between the first and second time it's happened.
Strange.

 

I just replaced the FOB batteries, and i5 did it again. But, in my fuzzy brain, I can’t remember if it had been in accessory mode since stsrting it last. Drat..l

 

@XKDreams , I think your focus may be improved if to stick to the classic martini… with gin.
Vodka is for the kids ;-)

 

Try locking the XK every time that you walk away from it, even if the top is down.
Constant chatter on the CAN network prevents modules from going to sleep contributing to higher current draw.
You might also check the quiescent current draw per the attached document.
Note the time for modules to sleep is reduced significantly when the vehicle is locked.
Software updates on some early XKs addressed the issue.
You might also try one of those inexpensive volt meters that install in the cigarette lighter to easily monitor system voltage.
Let us know your results.

 

Age's completely irrelevant, brand new batteries can also fail. Have you actually done a proper load test of the main battery?

 

Yes…done at Battery Plus.


BTW…since I’m not using accessory mode, haven’t had the issue. (Fingers crossed)

 

Please keep us posted. Many seem to want to point the finger at the battery, yet mine has done it a couple of times with a brand-new battery (tested and good). Makes me wonder if it's really a battery issue or some other little odd gremlin.

 

And as suggested by @bydand , press the brake pedal HARDER to ensure the brake pedal switch is activated. There are times where I nearly seem to stand on the pedal. As a result, I (and all those who drive my cars) follow the following procedure:

1. without depressing brake, depress and release start button.
2. ensure all accessories are off. (We do this prior to shutdown)
3. wait for all dings, chimes, whirrs to cease
4. depress brake pedal, press and release start button.
5. wait for idle to “equalize” before taking off.

Reasons for my madness
1. allowing sufficient time and voltage to power up necessary modules without incurring a failure due to voltage drop across starter.
2. allowing time for fuel rail to pressurize before the start.
3. If only 1 “ding” and not 5?? there is an issue. Most probably a depleted battery.
4. It feels like a proper starting sequence for the starfighter or…

Cheers.

 

Seems like you’ve put too much thought into it.
Have you tried the reverse procedure? Originally posted by one of the good folks here:

1. Depress and hold the start button (you can wait as long as you want before the next step, I wait a couple seconds, remember you are still holding down the start button)

2. Step on the brake pedal
Car starts right up, every time. Never had this fail, never had to stand on the brake (with this sequence).

3. Release start button.

Try it, you’ll like it.

 

I won't... I did not include that between 1 and 4, I am taking a sip of coffee.

 

I adopted this idea as soon as I read it. Brilliant. Gives the modules a chance to boot up and stabilise before the cranking 'hit'. Thanks @kj07xk !

 

Mannnnn i hate to tell you this,but with those many error codes,you might need to just go ahead and get that thing serviced at your nearest Jaguar dealership.You shouldn't be having any error codes like that cause that seems pretty bad like a security function or something where it shuts the car down because of it

 

Well, I’m still on multiple days of no starting issues. It seems bizarre, but the only thing different is that I’m not letting the kitty sleep overnight after running her in accessory mode without starting her up after that. Crossing fingers…