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When the engine is running the icarsoft will give you the alternator output voltage this should be 14.6 volts but this is controlled by the BMS and gateway unit, the gateway unit decides the small battery charge as well.
Do as Cutlea01 suggests. If the charge goes up to over 14 volts with the engine running the alternator will be fine.
When you changed the battery you will have reset all of the systems, which may have temporarily reset a faulty module on the CAN Bus which would through lots of fault codes.
 

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Looking again at the codes you put up It does look as if you may have fitted the brake switch incorrectly, probably worth looking at it again check that all of the cables are ok. The P0942 suggests low transmission fluid or blockage in the fluid cooler line. Having said all of that the battery voltage could do the same.
 

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Have you run the car or charged the new battery since you received it? Even though it is new, it may not be fully charged when delivered and if you haven't been on a longish run, it will soon discharge if you are leaving the car on and doors open and doing tests. As said above, charge it up and measure voltage after it has stabilised. Alternators can appear to charge but cause a parasitic drain on the battery when standing, so don't assume because it charges it isn't the problem.
 

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As antf say's above an alternator can discharge the battery but very rarely if it is charging correctly, this would be due to a diode going short circuit or regulator having a faulty component. Checking a parasitic drain on the battery is a good idea though, but easier said than done without correct gear. You may be able to tell by watching the icarsoft readings over say one or two hours disconnect it each time though. Whatever you do the next step is to make sure the battery is fully charged.
 

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As far as i can remember i upgraded number plate lights into led’s like couple of months ago and then a month ago i got new Xenon Headlight bulb, maybe these are draining out the battery.
I’ve been asked to self isolate today so can’t do anything much on it but theoretical solutions. i hope car starts after 10 days
 

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Looking again at the codes you put up It does look as if you may have fitted the brake switch incorrectly, probably worth looking at it again check that all of the cables are ok. The P0942 suggests low transmission fluid or blockage in the fluid cooler line. Having said all of that the battery voltage could do the same.
Transmission fluid seemed to be okay. if it was just a reset then the faults would’ve disappeared when i took both terminals out to reset but they did go after a new battery.
so it all comes down to parasitic drain. just need to figure out if it’s alternator or something else. on a side note i got new led number plate light and xenon bulbs light couple of months ago
 

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I’ve been asked to self isolate today so can’t do anything much on it but theoretical solutions. i hope car starts after 10 days
Oooh, that's not fun :rolleyes: Hope you stay negative and show no symptoms. I'd be very, very tempted to get a battery charger/conditioner connected up and leave it, such as a CTEK MXS 5.0 (I use Lidl equivalents!). Leaving the battery discharged and still connected for 10 days could well kill it or at least shorten it's life.
 

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I would charge the battery and check the voltage drop over a few days and repeat with the battery off the car. If it drops when not connected you know battery is faulty. You can measure a drain on the battery with a multimeter (YT can be useful) but would probably need to either lock the car or let it turn stuff off or you will be getting a reading that is normal for the car, but could look like a drain. Last time I did this it was on an older car with less electronics. But, if you do get a possible current draw you can then start to pull fuses to locate the circuit the drain is on. Unless the iCarsoft device can do this kind of thing?
 

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I ordered Exide batteries from Tyna both auxiliary and big battery, replaced them but the fault didn’t go this time. not sure what the problem is.
 

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I think that is the one they use at the factory to test the systems.Don't worry about it.
 

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Just took it on a motorway and the voltage won’t go up 12v with engine running . i think it’s the faulty alternator. Any suggestions?
184863
 

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In my car, the alternator got to the point where it couldn't even keep up with the load for regular usage and car was going into limp mode and couldn't start on battery which was having a voltage unusable for starting up.
 

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Hi all, After many years of hassle free driving, my XJ (2011 Diesel) has started doing the same thing. Random "Gearbox Fault, DSC not available, Park Brake Fault" - usually all together and a restart (or 2) clears it. My battery was original and 10 years old, so I replaced it and the problem seemed to go away for about a month. Errors came back. How do I locate the break switch and replace it? Where is the electrical junction box that someone found to be the fault?

Cheers
 

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Not sure what switch you are referring to, but it sounds like either the replacement battery is faulty or the alternator isn't charging. A cheap tester (around £10) will allow you to check the voltage when the car is running. It should be over 14v - if not you can look at the alternator as the issue. Most garages will be able to test this easily but will maybe cost more than buying a multimeter. The junction box issue is perhaps the water/washer pump/junction box problem found on most facelift XFs. Brake pedal switch problem usually results in not starting but the messages you have look like a battery voltage issue from what you describe.

Have you checked battery terminals are tight and clean?
 

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Not sure what switch you are referring to, but it sounds like either the replacement battery is faulty or the alternator isn't charging. A cheap tester (around £10) will allow you to check the voltage when the car is running. It should be over 14v - if not you can look at the alternator as the issue. Most garages will be able to test this easily but will maybe cost more than buying a multimeter. The junction box issue is perhaps the water/washer pump/junction box problem found on most facelift XFs. Brake pedal switch problem usually results in not starting but the messages you have look like a battery voltage issue from what you describe.

Have you checked battery terminals are tight and clean?
Hi,
Brake switch was mentioned on the first page of this thread - which described my issues..

"Cheapest option is the brake pedal switch. No more than £30.
Then the battery. I replaced the battery first and it made no difference."

Is a new Bosch battery and I think the terminals are clean and tight. I'll check it tomorrow though just to be sure.

Is an XJ rather than XF, but I did have a problem about a year ago with a leak from water reservoir at the front right where hose connects to headlamp wiper. If it is easy to get access, thought it might be worth checking if the junction box mentioned earlier was around that same area and it it was looking like there was evidence of corrosion. If anyone can give me a pointer on that - I'd appreciate it.

Cheers
 

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Yes all 3 issues together usually point to the brake pedal switch
 

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Just read a post on another forum with similar issues and the body control module was the problem. The guy was getting similar messages and occasional not starting and swapped the brake switch. Garage ended up reprogramming the body module, according to the owner.
 
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