Multiple faults... stressing me out!

[LunarGrape]

I am hoping all of these are related as I've got loads of life stuff going on, and this on top is stressing me out as well.

In recent weeks:

• I had the stereo screen getting stuck occasionally at the Jaguar logo
• The trip meter has reset
• The clock has reset
• A red fault on startup stating "Hold foot brake and park brake together"
• A yellow fault on startup stating "Gearbox fault"

The gearbox fault showed this morning but everything works fine.

Does this all sound very much battery related?  I hope its as simple as that?

[Jon Hyde]

Hi Paul,

I can't explain what's going on (these cars are too complex), but as you're in Sussex (as am I), I'd suggest a trip to Arun Automotive in Ashington. I've had two XFs from them, and the service guys are great.

Good luck!

J

 

[Jimbov8]

1 hour ago, LunarGrape said:

I am hoping all of these are related as I've got loads of life stuff going on, and this on top is stressing me out as well.

In recent weeks:

• I had the stereo screen getting stuck occasionally at the Jaguar logo
• The trip meter has reset
• The clock has reset
• A red fault on startup stating "Hold foot brake and park brake together"
• A yellow fault on startup stating "Gearbox fault"

The gearbox fault showed this morning but everything works fine.

Does this all sound very much battery related?  I hope its as simple as that?

The first thing to do is fully charge the battery and then see what happens. After that you’ll need to have the codes read to see what the car is saying is wrong.

[LunarGrape]

I have checked it with a voltmeter from off and the charge was 11.98 and I read its meant to be around 12.6V

[Jimbov8]

18 minutes ago, LunarGrape said:

I have checked it with a voltmeter from off and the charge was 11.98 and I read its meant to be around 12.6V

That’ll do it, far too low. Fully charged should read 12.8v.

[Carl Gibbs]

I agree with Jim.

I used to work from home regularly and I would need to plug in my C-Tek charger once a month for about 24hrs as the car wasn't being regularly used and several minor electrical faults would pop up.

Since starting the new job back in December, I am driving about 65 miles a day, predominantly on the motorway, and I have had no battery / electrical issues at all (touch wood).

I can only assess that this is due to the amount of driving I am doing and keeping the battery topped up.

[LunarGrape]

Well here’s a quandary, on the next morning there were no errors and all was well. I checked the battery at work again and it was 12.48.
So is it a duff battery still? I appreciate it’s still not high enough but 0.5 higher than the previous day

[Jimbov8]

21 minutes ago, LunarGrape said:

Well here’s a quandary, on the next morning there were no errors and all was well. I checked the battery at work again and it was 12.48.
So is it a duff battery still? I appreciate it’s still not high enough but 0.5 higher than the previous day

The more you drive it the more charge will go into the battery. The fact you now have no warnings is proof of low voltage. Before you go spending on a new battery, give your existing one a full charge. If it still loses voltage then by all means replace it.

[LairdScooby]

2 hours ago, LunarGrape said:

Well here’s a quandary, on the next morning there were no errors and all was well. I checked the battery at work again and it was 12.48.
So is it a duff battery still? I appreciate it’s still not high enough but 0.5 higher than the previous day

A fully charged battery is 12.7V :

Your alternator should put out in the region of 15.1-14.7V depending whether cold or hot, the voltage may go up slightly on the upper level due to certain things like load etc, especially at idle but the battery is almost certainly a calcium/silver-calcium type which refers to the doping on the plates to prevent sulphation."Normal" lead-acid batteries have lead-antimony doping and need 14.4-13.8V to charge, the calcium increases the charging voltage by 0.1V/cell and with 6 cells, each of 2.2V (total 13.2V) you can see where the extra 0.6V of charging voltage is needed.

With so much electronics on cars thse days and so many things referenced to a stabilised supply of 5V, 10V, 12V etc and a variable battery voltage, it's easy to see if the battery drops below a certain level of charge, strange things will happen. To put this into perspective, many sensors work on the potential divider principle where two resistors in series divide the battery voltage. One of those resistors will be the sensor but these derived voltages will be compared to a known voltage from one of the stabilised supplies. To make the figures easy, let's say one of the stabilised reference voltages is 6V. Let's make a sensor where the resistance is 6k and is fed by a 6k current limiting resistor which provides a total of 12k Ohms. Call the sensor R1 and the limiting resistor R2, the voltage developed across R1 = VR1 = Vb x (R1/(R1 + R2) so in this example, VR1 = 6/12 x Vb (Vb is battery voltage) so at 12V, VR1 will be 6V.

If the threshold for a fault is 5.9V compared to the stabilised 6V supply, no fault will be shown but if the battery voltage drops to 11.5V, VR1 will also drop to 5.75V and hence register a fault.

Bit long-winded for a simple explanation but hopefully gives an insight into how these things work!

[JOE-DOT-COM]

Hi

Low battery will cause this, especially if its a diesel on startup, short runs will not allow the battery to recharge

ideally above 12.5 volts with engine off, if battery goes below 10.8 while cranking, it will put modules in fault.

youve not said what car it is but on S-types, XJ's and early XF's the battery voltage with the engine running will vary between 13.6volts and 15.3volts on first startup

but as allready said put it on charge overnight and see if it cures it

but start up take so much out of the battery, especially on diesels and a 15 minute run wont put back in what was taken out on startup

can recomend a CTEK smart charger which can be left on when not in use to keep the battery fully charged, CTEK as used by jaguar oe chargers

cheers

Joe

[LunarGrape]

Maybe that’s it then as my drive to work was about 15 mins. 
 

It is a MY10 XF and Portfolio so has all the electrical extras. 

[JOE-DOT-COM]

is it a diesel

[LairdScooby]

Maybe once a fortnight or once a month, take it for a longer run to give it a bit of a concentrated charge to help get round this problem. I use a 1988 Volvo 760 as my "Dogmobile" so its use is predominantly very short runs, however every once in a while i'll take it for a longer run to recharge the battery and blow the cobwebs out.

[LunarGrape]

4 minutes ago, JOE-DOT-COM said:

is it a diesel

Yeah. 3.0. 

[JOE-DOT-COM]

Just now, LunarGrape said:

Yeah. 3.0. 

Hi

Its the glowplugs on a diesel they take so much out of the battery on startup in the cold weather

as the weather warms up, its not as bad as the glow plugs dont stay on as long.

 

[LunarGrape]

Any thoughts as to which one I need as Yuasa suggests two that are quite different. 

YBX5019 SMF (100 Ah / 900 amps) or YBX9019 AGM (95 Ah /850 amps)

The one in the car is a Merc one that matches the 9019 numbers but my car isn’t a start/stop car? 

[LairdScooby]

If the 100Ah/900CCA will physically fit, get that one. Alternatively, have a look here :

https://advancedbatterysupplies.co.uk/shop/?swoof=1&product_brand=diesel-all-models-2008-present

A good selection from £95 upwards to £240..........