Too many faults to be true. I hope.
Been watching my tpms low pressure messages for a while now. Yesterday got a tpms system failure message...today hooked up Foxwell 530 scanner and after 15 fault messages it froze. Tried checking several modules, either got a passed message or failed to communicate. So many times that I realized that either my 2008 Xk is about to quit running or the foxwell has issues or it's the battery. I've sent a message to Foxwell, will see what they say.
Thoughts anyone?
WJ

 

It's ALWAYS the battery.

 

One of the first things I learned from this forum was....if things get hinky with your electricals, TEST the battery first for volts over 12.6V at rest, then RESET the electricals by removing the battery cables and touching them together for 20 seconds, then re-connect them.

 

That is my 1st thought.
Is there any difference from a 'fault message prone battery' on a maintainer and at 12.6+v to a new fully charged one?
Ie can I determine it is the battery short of swapping them out?
I have, big chargers, little chargers, 4~5 amp maintainers.
wj

 

Just a thought with no offense intended, but maintainers pushing that much juice might be drying out the cells. Have you checked water levels?

 

Don't start engine. Put a load on (headlights etc), wait a while (er, not ages) & see how much the battery volts drop.

Not as easy with a spare (if you have one), though!

 

There's so many variables with batteries and these cars. I've gotten as much a six years with the factory fitted one, and 3 years on the perfectly good AGM replacement before converting to lithium but then I've always used CTEK maintainers. As everyone always says, get the battery properly tested either your self or by a specialist. Check the voltage after the car has been sitting overnight without a charger or maintainer and then apply a load with the engine not running, such as turning on the radio, headlamps etc and watch the voltage, if it starts dropping quickly below 12.6 volts it's likley the battery. A 4-5 amp maintainer'ss perfectly fine in fact that's what a CTEK does and a higher amperage charger's what you need to properly charge the battery (trickle chargers take forever and aren't the best for high amp hour AGM batteries.

 

Can we assume that only a maintainer that's automatically going to stop charging at 4-5A should be used? Cheap maintainers that keep charging will deplete the liquid if it's a wet-cell battery. I know nothing about how AGM batteries charge, if they're different from wet-cell.

 

Bamaboy473, you are probably correct as to lower water levels...checked it when I purchased the auto...time flies...that was 12 months ago, so I'll just assume it is low.
That probably isn't too important at this point, I know for a fact that the battery voltage in the morning with only the door open is @ 12.3v so a new battery is in store for me. I'll rely on the maintainer for another several weeks and then replace the battery.
I'll try to put the fault messages in the back of my mind until I replace the battery. The car seems fine and other than the tpms messages on the dash everything is good to my knowledge.
thanks everyone


wj

 

The good news is that you might have solved the mystery!