I need a favor from someone with a 2008 or 2009 XJ (X-358). I have a parasitic current draw that is draining the battery over 3-4 days. My mechanic (former JLR tech) claims it is a short in the air suspension circuit because it is drawing 60-100 milliamps when the car is off. This car has an Arnott coil spring conversion with the electronic bypass module (EBM) to fool the dash warning light to stay off and its worked fine for 5-6 years - the ASM is totally disconnected. If I unplug the EBM the drain goes away, plug it back in and the drain is back. The favor I am asking is for someone to pull the 20 amp #52 fuse in the boot and measure for a current draw across that socket. My goal is to determine if that 60-100 milliamp draw is normal. Would prefer this be done to a car that still has the stock air suspension in place. Appreciate any assistance you can provide.

 

Parked&Locked, my average current draw is 36mA (measured via trickle charger).
Unlock car, pull F52 and stick a meter across, I get 0.1 to 0.11 amps (and an initial funny noise). I don't think this is a valid test for quiescent current.
I think I'll delicately reconnect everything and go back to sleep.
(I have stock air suspension. "still". )

Incidentally, 100mA over 4 days is 9.6AH, nowhere near enough to drain a GOOD battery (that started off fully charged!).

 

Chris, thanks so much! That confirms what I thought - that small amount of drain in the Air Suspension circuit is normal so my mechanic needs to look for another parasitic drain someplace.

 

Sounds like the car is not able to put itself to sleep.
One of the subsystems is not satisfied it has reached its standby status, thus it is probably keeping other systems awake as they poll for updates.

Just putting it out there........
Oddly that was a problem that seemed to also pop up with the X400, and one of those members seemingly tracking it to a valve in the heater assembly not closing and keeping the CCM module from achieving a true rest state.
That if I recall was causing a persistent battery drain of around 130-150mA, but when resolved the battery drain was 30mA. That is for the x400 mind you, so it doesn't have as many subsystems as the x350 series.
Similar production years, so might have similar sub-components and architecture.

 

Thanks Mark - your comment about not reaching the car's shutdown stage is where I intend to have my mechanic focus. I have had a similar problem earlier this year traceable to the drivers door latch which is an integral part of the alarm system. Who would think a door 'latch' would cost close to US $700 in the box!

 

As a follow up to my little adventure with parasitic current drain, I want to express my gratitude to Marvin Noel, the Technical/Warranty Rep at Arnott Air Suspension Products. We can agree or agree to disagree about converting these cars from air suspension to coil overs, regardless, when I receive great customer service I believe in acknowledging it. Since my mechanic thinks the current draw has to do with the air suspension system I have had several phone conversations and emails with/from Marvin. He even sent me a new Electronic Bypass Module (EBM) for no charge in case mine had failed somehow - that's the little black box that fools the warning light and message to stay off after a change from air springs to coil overs - turns out mine was fine. Marvin and his engineers did decide to change one of my electrical connections from an "always on" circuit to one that turns off after the 40 minute wait time to remove the slight drain my mechanic was fixated on. Arnott's coil overs have been a decent solution to a failed air system on a high mileage car (180,000 miles) and their little EBM eliminates the warning like it is supposed to. If you are considering a coil over conversion I highly recommend Arnott for a good product at a fair price and excellent customer service.

 

Just another off hand suggestion.....check the ignition barrel key-way for the small shutter that gets pushed aside when you insert the Tibbe key.
That shutter movement operates a switch in the ignition assembly giving a "key in" signal to the security system.
If that little mechanism is occasionally binding, you might be getting some residual security computer activity thinking the key is still partially inserted (although transponder obviously won't be present, so the car won't necessarily bring up instrument displays).

A bit of dry graphite powder should free it up if it has become hesitant.