Hey All,

Need some help

Car isn't starting - It's a 2013 XF 3.0 SC AWD.

Pretty weird what happened. Worked fine yesterday, no issues at all, started up perfectly with no hiccups.

Went to turn it on today, it did half a crank, and shut down. Got the sign on the nav, that battery is low, system will shut town.

Boosted the car... no luck. The battery sign went away, but won't crack at all anymore.

All audio systems, nav, lights work fine, EXCEPT for the back tail lights.

When I press the breaks, or lock the vehicle, all the lights flash, except for the tail lights. The soft close trunk also does not engage.

When I investigated further, I noticed some water around the back fuse box. I imagine it is from washing it yesterday, not sure how it got in, but looks to be some getting in.

Question I have for you all..... Is there a chance the starter (where there is ZERO crank) and back tail lights, and soft close trunk are all linked to the trunk/luggage fuse box?

I looked in the manuals, don't see any fuses in there that may be linked. Have waited about 8 hours for it to dry, no luck with it starting yet.

Please help! TIA!

 

With the ignition in the OFF position, use a voltmeter across the terminals to read the available battery voltage. There must be a minimum of 12.6 volts for all modules to fully function.

 

confirmed this. Getting 12.6 out of main battery

 

When you press the brakes to start the car, are the brakelights coming on? With loss of vacumn from the servo, sometimes you need to really stand on the brake pedal to start the car. Water in the rear fusebox could also effect the brakelights & therefore stopping the car from starting.

 

Very common for the sunroof to leak into the trunk and/or front footwell on these cars. The fasteners that adjust the sunroof may need attention. The weather strip may have shrunken a bit allowing more water into the cavity than can be drained properly. The drain tubes may also be unhappy, clogged or shrunken.

 

key recognized?

cjb replaced yet?

 

no break lights. Regardless of how hard I press them.
no flashing lights when locking/unlocking the vehicle.

Is there fuse in the back box for back taillights?

soft close on trunk isn’t working either.

 

key is recognized. Car goes into ACC, but nothing onwards.

I believe it does recognize me pressing the brakes. As when I press it without brakes car goes into ACC but gives message to press brakes. When I press them the message goes away, however still zero crank

 

The vents hidden behind the bumper, just below the rear lights are a well known culprit for water ingress.
Have you checked the wheel well ( under to boot/trunk floor ) for water too?
The rear lights, and soft close trunk are all controlled by that rear junction box, so it's worth suspecting water damage there.
If it were me I'd disconnect the battery ( make sure the car is unlocked, the drivers door has since been opened at least once ( so the alarm doesn't auto arm ), open the trunk, place the keys well away from the car and wait 30 mins for the modules to shut down without opening or closing any doors, before disconnecting the battery, - otherwise it can cause module corruption which may already be your problem due to the discharged battery) for safety reasons always disconnect negative first, and reconnect last.
Then I'd un-plug everything from the rear junction box, and take it indoors open it, up and leave is somewhere warm to dry out. ( but not hot - no trying to rush it by putting it in the oven! ) Check for corroded contacts too. Then refit, and reconnect the battery and see what happens.
Failing that, you should try and get someone with SDD to read your fault codes, and check the VIN numbers in your modules - scrambled VIN in the BCM, or BCMB ( that "fusebox" with the water in) generally indicate the emulated eeprom has got corrupted due to low battery, which can often be fixed with a BDM programmer like xprog-m provided there is no attempt to reflash the module using SDD first. But all bets are off with water damage.

 

thanks

took battery off, no luck

dried of junction box, no luck

tested all fuses. All are good.

no clue what it would be. I’d imagine if junction box went bad or shorted, I’d see a bad fuse somewhere.

 

The "junction box" ( Body control module B ), is actually a computer that just happens to have a few fuses in, most of the outputs are electronically overload protected and self reset once any shorts circuits are removed. If it's all dried out and still not working, then either it's physically damaged due to the water shorting stuff internally, or if you're lucky ( well kind of lucky if you can get it reflashed as they are very expensive to replace ) it could be the fault I mentioned last above. Which very commonly causes no-crank.

 

they are ridiculously expensive to replace. Asked for part cost, got over $5,000 CAD without programming.

would you happen to know if I source a used one (there’s few on eBay) can that be reprogrammed to my vin?

 

There's a junction box in the back that all the heavy red cables go to, inside that are some mega-fuses, worth a look in there!

 

My understanding is that the only way to program a used BCMB is to get the exact same revision you already have, and provided the SoC ( System on a Chip ) of your original one is not broken, clone from the old one to a new one with a BDM capable programmer ( usually Xprog-M seems to be the programmer of choice ) then use SDD to resynchronise the security codes. In theory if you had a flash memory dump of an unused BCMB that could be used, but I've never heard of anyone getting hold of such a dump. ( Though I'm sure I have seen one around the forums for one revision of BCM ( the junction box in the front footwell ) )
But before you go buying BCM or BCMB you should really get the fault codes, and data for the modules read with SDD, if the VIN is corrupt in BCM or BCMB ( as can happen just by disconnecting the battery / allowing it to get discharged too far ) it can often be fixed with a BDM programmer as the data that gets corrupted can be reconstructed from a dump of the d-flash - provided you don't try to fix it using SDD first ( which often seems to leave folk with a car that can be started, but none working windscreen wipers )

 

car is throwing current codes U0151-08 = Lost communication with restraints control module

B10A2-32 = Crash Input

U0447-00 = Invalid data received from gateway A

first two are airbag / crash related obviously. Doesn’t make sense. Car was in an accident 4 years ago, but minor - no airbags went off either.

not sure what Gateway A is however

any clue?

 

Thanks - checked every fuse in there... no issues...

Starting to think computer may need to be reprogrammed.

Damn these cars.

 

The immobilizer might think the car was in an accident and preventing the car from starting.

 

any way to get around that/reset it? Or only dealer can do that?

 

Occam’s razor: faced with a conundrum like this, the easiest answer is most likely the correct one. The combination of symptoms STRONGLY suggests a battery that fails under load ( i.e. the starter motor). Yes, it may register 12.6 across the terminals but the sudden load of the starter sends the battery into failure territory.
This is a fairly common failure pattern of modern batteries - fine one day, and useless the next day. I have had exactly this happen.

Before you spend both time on money in going down the rabbit hole, consider installing a new and FULLY CHARGED battery.

 

Test battery with Medtronic or similar. You could have a bad cell. Especially if it's a Duralast or Neverstart.