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Discussion Starter · #1 ·
Hi, first message, please be gentle :) I'm not a car expert, but I have a technical background.

I'm trying to learn about a 2008 XF Premium Luxury (RHD, UK), which I have recently bought privately. It tested fine, no warning lights etc. There was a problem with auto-locking the right two doors, and both right windows didn't open. I took it to a local garage to repair the driver's door lock and the window mechanism, and both are now fine. The rear right lock and window still don't work automatically, but that's not a priority. They also replaced the original Jaguar battery (13 years old) with a brand new Yuasa 3000. I would have preferred the 5000 but anyway.

This is where it starts.

About a week ago I went to start the car and the battery was totally flat - I must have left the boot or door slightly open or something, I think a light had totally drained the battery. After a jump start the car seemed fine - thought I've read a lot about electronics going wrong after battery changes/discharges. I drove it for about 12 hours last weekend with no problems until 2 days ago, when a red warning came on whilst braking on a main road: "Unable to apply parking brake" with a flashing red ( ! ) indicator and a solid amber ( ! ) indicator.

I have tried to reset it by disconnecting the battery for a minute, reconnecting, turning on the car and applying the EPB as instructed. The dashboard indicates that the EPB has applied (with a ( ! ) ) but it also displays ( ! ) and "Parking Brake Fault." Assuming it is applied, when I drive off the brake is released and the red light goes off, but then the original "Unable to apply parking brake" message comes up.

I've noticed, also, that when I press the footbrake - even lightly - there is a slight clicking noise beneath the EPB lever in the centre console. I haven't noticed it before. Can someone verify this? Could it be a problem with the switch rather than the EPB actuator and motor?

Is there anything else I can try before getting the EPB parts replaced? Also, could this issue be linked at all with cruise control? The speed selector seems to be "misbehaving" a little and I don't know if they're linked. Given that so much of the car is electronic, I wouldn't be surprised!

Thanks for reading this, any help and advice would be greatly appreciated.
 

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Hello & welcome, stay safe.

What is the specification for the new battery? It really needs to be at least 85ah, around 900 cca. These cars are extremely reliant on having electrics in good working order.
 

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Hello MitKat (we like first names). Welcome to the forum.
As Ian (@idrobbo ) has said, the XF is very sensitive to battery condition and I don't think the Yuasa 3000 is up to the job. At only 76A and 680A CC it really isn't beefy enough for the XF. I think your EPB warnings are linked to this. I'd take it back to the garage that fitted it and tell them to replace it with the CORRECT battery.
 
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Have to agree with John, they have fitted a battery that is totally unsuitable for the XF, the higher the Amp Hour the better, I only fit 100AH batteries to mine. Phil
 
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Discussion Starter · #5 ·
They battery they put in is a YBX3110 80Ah 760A CC. I was going to change it myself to a Yuasa 85A 800A CC battery, but given that they were working on it I decided I'd let them do it. I wish I'd done it myself now.

It was about 3 months ago and they will probably remember me - I have all the paperwork - but if they refuse I might just bite the bullet and buy a higher spec battery myself. If it saves me hundreds on an EPB module and motor it'll be worth it.

Thanks all! One day I may try and change the rear door's locking mechanism myself... I've seen it on YouTube, so it must be easy, right? 😄
 

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Don't forget to reset the BCM after changing the battery. Phil
 

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Discussion Starter · #7 ·
Don't forget to reset the BCM after changing the battery. Phil
Do you mean the battery monitoring system? I've read various things on this forum, and others, where some people say it's really important and some people say the BMS is self calibrating. I don't know enough to say which is right or when. I've been advised to get an ODBII reader (bluetooth, to connect to my phone) for diagnostics. Will I be able to reset the BCM/BMS with the right app on my phone, or do I need a handheld unit?

Or is the BCM something different entirely?
 

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I wouldn't worry about that. It's a bit more problematic in later models with the auto stop/start system. As you say, yours will self learn when the battery is in.
I never did it with my 2010 XF and had no issues whatsoever.
 
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Do you mean the battery monitoring system? I've read various things on this forum, and others, where some people say it's really important and some people say the BMS is self calibrating. I don't know enough to say which is right or when. I've been advised to get an ODBII reader (bluetooth, to connect to my phone) for diagnostics. Will I be able to reset the BCM/BMS with the right app on my phone, or do I need a handheld unit?

Or is the BCM something different entirely?
Look at the Autel AP200 only £45 & does everything you need!!
 

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Do you mean the battery monitoring system? I've read various things on this forum, and others, where some people say it's really important and some people say the BMS is self calibrating. I don't know enough to say which is right or when. I've been advised to get an ODBII reader (bluetooth, to connect to my phone) for diagnostics. Will I be able to reset the BCM/BMS with the right app on my phone, or do I need a handheld unit?

Or is the BCM something different entirely?
For the first three battery changes the BMS appeared to calibrate itself, but on the last batery change even after three months it would not calibrate and necessitated the use of the iCarsoft, so they do not always calibrate themselves in spite of what some people claim. Phil
 

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For the first three battery changes the BMS appeared to calibrate itself, but on the last batery change even after three months it would not calibrate and necessitated the use of the iCarsoft, so they do not always calibrate themselves in spite of what some people claim. Phil
But what problems/consequences resulted from the BMS not resetting itself?
 

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The battery never seemed to fully charge, and the radio cut out after 3 minutes without the engine running even after fully charging the battery, after I did a reset it immediately went to where I could have the radio on for over ten minutes with engine off. It definately made a difference to the cars ability to charge the battery. Phil
 

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Discussion Starter · #14 ·
That's interesting @Philayl . The dashboard indicates a low battery pretty much every time I switch the ignition on without starting it, so perhaps the BMS "thinks" the voltage is low. I have no idea if the garage reset it, and I don't generally sit in the car for long periods with just the ignition on. Having said that, it doesn't sound like a non-reset BMS would affect the normal running of the car while the engine is on - unless the BMS is so out of sync that the car stops charging the battery. Which sort of leads me to my next question - which may be a stupid one, but I'd be more stupid to not ask it.

Why would an 80Ah battery cause a problem while the engine is switched on, given that the alternator is running? The alternator seems to be fine, and the battery is charged so I have no reason to suspect that as a problem. If the car was struggling to start each time or certain electric functions worked slowly/poorly while the engine was off, wouldn't that be an indicator of an insufficient battery?
 

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Hi, it is difficult for me to explain, I'm not very good at it, but I will give it a go. The BMS thinks that the old battery is still connected and will only charge it to a certain point, so although you have a new battery it will not get fully charged unless the system is told that a new battery has been fitted, that's why they say the BMS is reset, it starts from scratch, it basically wipes the BMS memory. Someone else might be able to explain it better. Phil
 
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Good enough description Phil.. but we may never understand the JLR 'logic' of how it actually works... :)
 

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Discussion Starter · #17 ·
Hi, it is difficult for me to explain, I'm not very good at it, but I will give it a go. The BMS thinks that the old battery is still connected and will only charge it to a certain point, so although you have a new battery it will not get fully charged unless the system is told that a new battery has been fitted
Yes that makes sense, and it's what I was getting at when I said the BMS was out of sync. But I don't understand why it would cause a problem while the alternator is running. The EPB runs off a 5A fuse which isn't a great deal of power, especially for the short time it takes to apply/disengage the brake. So, depending on how much power is being used normally, the battery would have to be very low for it to cause problems while the engine is running... right?

If so, wouldn't that point to the inability of the battery to hold charge, either due to a fault with the battery, or a problem with charging such as the BMS requiring a reset or a faulty alternator (which I doubt)? Why would a greater capacity battery make a difference? FYI the original battery was 90Ah/800A so I intend to find out why the replacement battery is a lower spec.
 

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As I understand it the BMS controls the alternator output, so it will not just keep charging just because the engine is running. I would fit the correct battery with the highest amp hour you can and reset the BMS then work from there. Phil
 
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Here's what it says in the 2010 workshop manual . . .

When the ignition is off (power mode 0), the BMS control module records the primary battery state of charge and begins to monitor the battery condition from this point.
If the battery state of charge falls by 7%, the BMS control module will monitor the primary battery for 5 minutes. If after the 5 minute monitoring period, the primary battery charge has continued to fall due to the quiescent drain current being too high, the BMS control module will determine that some control modules are still 'awake'. The BMS control module sends a shutdown message on the LIN (local interconnect network) bus to the GWM (Gateway Module). The GWM sends a CAN (controller area network) bus message on both the medium and high speed networks to all control modules, requesting them to shutdown.
The BMS control module will monitor the primary battery state of charge for a further 5 minutes and determine if the primary battery state of charge is still dropping. If a quiescent drain current continues, the primary battery state of charge will continue to drop. If the state of charge falls to 12% of the initial monitoring value, the BMS control module determines that one or more control modules are still awake and a failure to respond to the shutdown request may indicate an error state within the control module(s).
 
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Also . . . .
BMS Control Module Self Calibration
Periodically the BMS control module will instigate a self-calibration routine. To self calibrate, the battery monitoring system first charges the battery to its full condition.
NOTE: If the vehicle is only driven for short periods the charging process could take a number of days to complete.
Once the battery is fully charged, the BMS control module will discharge the battery to approximately 75% of its full state of charge, but never lower than 12.2 V. The time taken to complete this part of the routine is dependent on the electrical load on the vehicle.
When the second part of the routine has been successfully completed, the BMS control module will return the battery to its optimum level of charge. The optimum level of charge will be between 12.6 V and 15 V, depending on battery condition, temperature and loading.
The BMS control module also monitors the primary battery condition with the engine switched off. If a low voltage condition is detected the BMS control module can request the infotainment system is switched off to protect battery voltage.
 
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