... This will be the heater speed, resistor playing up I should add.. 2008 L322 Vogue 3.6 TDV8 in Java Black with parchment and Navy interior. 125000mls.

I used to be indecisive and have a split personality... but we are ok now...I think?

None of the forum posts I've seen have said definitively whether you can have a fully functioning blower (ie: all the speeds appear to work, it responds normally to the controls) and it still be faulty.

Can this 0.2amp parasitic drain (which is intermittent) be because of the FSR?

Can I check this by disconnecting the FSR seeing if it helps?

Considering the car is quite new to me, I've no idea what a fully functioning blower looks/sounds like either... It seems a bit weedy on full power, but then maybe it's meant to be like that. Turning from off to fully-on indeed shows a steady progression in fan speed, so it "seems" normal to me.

As it stands right now I just went out for a longish drive (1 hour or so) and came back, locked up the car and I've 0 draw on the HVAC fuse (left the meter connected). Battery is fully charged and holding steady.

Hazard warning backlight and the screen backlight are both off - they go out "around" the same time the 0.2amp drain disappears, but not at the same second - so I think they're coincident/related but not the exact same issue.

To me, my issue looks like the BCM is staying awake, causing the cabin air temperature fan to be activated and that 0.2amp drain (probably coupled with the backlight draw for the screen and hazard warning switch) is flattening the battery.

It could be the FSR is the reason for the 0.2amp drain and this is in turn keeping the hazard warning switch backlight on and the dash backlight on, but this is just a guess.

It's certainly intermittent, which again suggests to me it's not the FSR as with the FSR being a big dumb lump of resistors they seem likely to either work or not, rather than being variable - though, this again could be wrong, could be due to temperature or something.

Pulling my hair out!

After a long drive yesterday (starting with a fully charged battery) I left the car overnight with the battery monitor logging the state of charge.



From 7pm yesterday (when I parked up) until approximately 4am this morning, the battery remained fairly constant, the current meter connected to the HVAC system showed 0 drain and the backlight on the hazard warning switch and the backlight on the instrument cluster were both off.

At approximately 4am, as you can see on the graph, something happened, there's two short dips which look like more than 200mA being drawn from the battery. Battery then seems to hold flat for a while before again something 5:30 causes it to dip quite drastically - there's then a constant drain from about 5:30 up until about 10am when things start to get a bit interchangeable again.

The longer slower dip between 12:30 and 13:30 I witnessed as a 0.2amp draw from the HVAC (though, there may have been other things drawing more current too).

I think I'm more confused than ever now tbh

13:30 I put the battery back on charge. I'll let it charge up again until this evening and then pull the fuse on the HVAC. My theory is that this will show if the current drain is *caused* by the HVAC or whether there's something else waking up which is in-turn, causing the HVAC to be woken.

My working theory is still that something else is waking the BCM, the car thinks it's about to be opened so it wakes up the HVAC to start checking the temperature etc.

I also tried (briefly) covering the sensors on the rear-view mirror, I wondered if sunlight hitting the windscreen was causing one of the sensors to wake the BCM or HVAC ECU's as the temperature in the car changes - that big drop in current at 5:30am is probably around the time it's starting to get light, just a hunch.

See if you can find any info on the suspension system checking itself for being level when the car has gone to sleep. I know I've read it somewhere.

Yes, it could definitely be that - I've seen it quoted as happening 1 hour and 24 hours after shutdown, which doesn't exactly coincide with this but it's a possible.

In theory, the suspension only *drops* to level itself, so the compressor doesn't kick in it'd presumably just be some valves opening. I would think that's what may be happening between 4:30am and 5am.

That kind of drain would be fine though, it's the rest of it that's the problem!

Todays update in our ongoing battery saga...

Pulled out fuse 62 (HVAC control) entirely and left the battery monitoring in place overnight again.



Looks to me like there's still a consistent draw. However, at 1am, you can see the graphs angle changes slightly - this is the point where I turned off the app on the iPhone I'm using to monitor the battery draw, it looks like the act of "live monitoring" it via Bluetooth uses a bit of juice.

I'll stick a multimeter on the car today to see how much the battery monitoring device uses, it *could* be it's now the only source of current draw and disabling the HVAC control has indeed cured my problem.

I think it's fair to say that there's no way a healthy battery should be completely clobbered by such a short period powering a small microcontroller, so it's pretty evident to me at this point that my battery is shot.

I have one on order already, just waiting for it to turn up (14th December!).

Next steps:
- Charge the battery back up, disconnected from car.
- Test battery monitor to see how much it draws, both in passive logging and active modes (before 1am was active, post 1am was passive)
- Start looking for other fuses causing current draw
- Think about how to deal with the issue on the HVAC ECU.

I'm still unsure if disabling Fuse 21 confirms the FSR is OK, or whether it suggests it isn't - feedback very welcome from anyone who can confirm!?

where is fuse 62 ? i only have fuses go up to 60 in glove box !!

Could be model year differences, mine's a MY2011 and this is the fusebox and the associated listing for it.

There's some definite quirks though, for example, as far as I can fathom, fuse 57 looks like the interior lights but pulling out that fuse leaves all the interior lights still on :\

hiya, where is this fusebox located!! under the bonnet, boot, , i think my layout is different

bob

Bob, On your Model Year Air Conditioning shows as fuse 12 in the fuse box behind the glove box. Try that to see if you get a result.

PS. Haven't seen you for a while trust you are well.  John
2008 Stornoway Grey 3.6 Tdv8 Vogue
2005 TD6 Java Black Vogue - Written off!!
GAP iiD BT
2003 Discovery TD5 Auto, Nanocom Evolution - gone to a new home!
MasseyFerguson 152 - No electronics!! - Sold

BOBCUSSEN wrote:

hiya, where is this fusebox located!! under the bonnet, boot, , i think my layout is different
bob

The one pictured above is the fusebox behind the glove box, on a MY2011 TDV8 4.4.

There's also a bunch of fuses just in front of the battery under the bonnet (on a LHD vehicle, I guess on a RHD vehicle it's also in front of the battery even though the battery is on the other side?)

Lastly, there's a fuse box in the right hand side rear of the boot. Which has some more fuses, including some relays and some larger 40amp fuses.

Again, all this on a MY2011 4.4 TDV8, others maybe a little different

Updates on the above saga...

I measure the current usage of the battery monitoring device and it was in the 20mA range and usually much less, so I've discounted it as being statistically significant and have left it connected.

I've swapped the battery for a new one, but I'm still seeing the same behaviour, if anything, on the first night I saw *more* voltage sag overnight than before!

I'm suspicious that the Naviplus I fitted is the source of the problem, in that it's potentially keeping the BCM awake - having emailed Naviplus they've suggested disconnecting the yellow (I think this is supposed to be an "accessory on" feed) and driving it direct from the fusebox on an ignition-on feed. I've not done this yet, I'm not convinced it's going to help tbh.

I'm still waiting for a clamp-type multimeter to arrive to I can non-invasively test the current draw around the alternator. Also still waiting for some new test leads to arrive for my multimeter, which have got destroyed

Lastly, I pulled the HVAC control board from the dash and took it apart to check for any signs of corrosion or possible reason for the fan staying on. It was immaculate inside, aside from a bit of dust where you'd imagine around the vent, but I see no reason to suspect it as being damaged by water or anything.

As an FYI, the way the temperature sensor and fan are mounted, there should be no issue in gently blowing dust out of that grille with an air duster, it vents to the back of the dash and I can't see how it'd do any harm to it.

So not much further, but I'll update the thread again when/if I find something more out!

Weegie wrote:

Bob, On your Model Year Air Conditioning shows as fuse 12 in the fuse box behind the glove box. Try that to see if you get a result.

PS. Haven't seen you for a while trust you are well.

In the front fuse box they only go up to 60 on yours. They then start at 71 on the rear fusebox. No 62. John
2008 Stornoway Grey 3.6 Tdv8 Vogue
2005 TD6 Java Black Vogue - Written off!!
GAP iiD BT
2003 Discovery TD5 Auto, Nanocom Evolution - gone to a new home!
MasseyFerguson 152 - No electronics!! - Sold

hi john,

thanks i will take a look



bob