Tracked down a Quiescent Current Drain today to the Climate Control F14 in the passenger fuse panel of my 2000 S-Type. Car stays ~800mA past the 45 minute mark, goes below 30mA with that fuse pulled.

Before I pull the dash apart, is there anything but a faulty module that can cause this? Wondering if it might be easier to check some of the sensors.

 

Are you positive about that fuse location? I’m looking at figure 01.4. Fuse F14 feeds switched ignition power to the module. Power to the fuse comes directly via the ignition switch.

When the ignition switch is off, there should be no power to that fuse. In that case, pulling the fuse should make no difference.

I would have to say you’ve either got the wrong location or that pole of the ignition switch is sticking on.

 

Maybe I screwed up prefixing it with F. I'm talking about Fuse #14 in the Primary Junction Box -- on Fig 01.4 (Ignition Switched Power Distribution) of my 1999.25 book. It's a 10a fuse.

 

That is the same fuse and diagram I mentioned. The fuse should not have power with the ignition switch in the off position.

Something doesn’t add up. Check for battery power at this fuse.

Key on = 12+ volts
Key off = 0 volts

 

Battery drained to ~9.6V overnight, so need to charge it up, but I now have 9.6V with the ignition on and 0.041V with the ignition off.

So it sounds like _some_ voltage is getting through when the ignition is turned off. Time to replace the ignition switch?

 

Key off, you measured 41 thousandths of a volt. That’s essentially zero and looks good. Digital meters often show an insignificant fraction at zero, as you have recorded.

I am still scratching my head over how pulling this fuse has any effect with the key off. Your latest reading shows power is not present when the car should be going to sleep.

We are talking about the panel inside the cabin, right? Down by the US passenger’s feet? Since you’d have to open the door for access, I wonder if that is waking up some modules and skewing the results.

 

I went through the process. I left the trunk open, closed the latch, and used duct tape to cover the button for the lights.

Have a current clamp meter between negative of the battery and ground. Tried each fuse and locked the car each time.

Stock drains, drain went away when I pulled the 40amp cabin fuse. By process of elimination, 14 was the fuse that made the difference.

But now I'm with you, this seems strange. I wonder if me toggling the key to test this made a difference? As in the ignition switch sometimes leaks and sometimes doesn't.

 

40A cabin fuse? Do you mean fuse #25 in the trunk? See figure 01.2. That fuse feeds NON-switched (constant) battery power to a portion of the primary junction box inside the cabin. Power from this fuse does NOT go to or through the ignition switch at all.

Fuse #14 (in the primary junction box) is NOT downstream of that 40A fuse in the trunk. Maybe you got lost switching between pages in the wiring diagrams?

 

Hi Brandon2,
I've seen this type of issue briefly mentioned in the X-type forum too.
https://www.jaguarforums.com/forum/x...-drain-243660/
In those it appears to be a CCM piston jamming and not letting the climate control systems hibernate....perhaps something physically similar for you too.

 

I’m not sure I buy that theory, whoever came up with it. AFAIK, there is no feedback for the position of the two valves in the DCCV. Each valve is just an electromagnet pushing the piston closed against a spring.

Full power on = valve closed
Power off = valve open (default position)

When less than full power is applied (pulse width modulation, a fancy term roughly equivalent to reduced voltage), the valve only opens part way proportionately.

The two valves each receive constant battery power and the module supplies a separate variable ground for each side. When the ignition is turned off, the control module switches off the two grounds and the valves relax to the open position.

You could test the theory by pulling the fuse that powers the DCCV, or undoing the connector.

Alas, this may all be a moot point. No follow-up from the OP going on five days now. This may end up as another unresolved phantom thread…

 

I'm back -- hard for me to find time to diagnose during the week.

I left Fuse #25 in the rear power distribution box out all week, and the battery was close to where I left it.

I pulled Fuse #14 today, and it no longer seemed to eliminate the drain. I'm not sure how to explain what I saw last time other than an ignition switch on the fritz, or I somehow goofed up.

In any case, I dug in again, I found that fuse #18 (20 amp) in the primary junction box, which I believe goes to the radio now seems to be the culprit of the drain. Does this make more sense?

 

Yes. This fuse is downstream of fuse #25 in the trunk, so that makes a LOT more sense.

Fuse 18 in the primary junction box does feed the radio, and possibly two other items.

With the standard sound system, it only feeds the radio head unit.

With the premium sound system, it feeds the head unit and a center fill amplifier. The amp location is “adjacent to steering column” with no other details.

If equipped with the nav system, the fuse also feeds the display unit.

Being cheap and lazy, I’d unplug the radio head unit first and see if that does it.

Does the car have any aftermarket equipment, such as a radar detector, fancy stereo, cell phone cradle, etc.? Installers often tap into the radio memory circuit, so maybe something like that is killing the battery.

 

One more thought on this theory. Strictly a guess, but there may be some INDIRECT feedback for the position of the valves.

The system has a temp sensor for each of the two discharge ducts. The temperature value MIGHT be used to see if the associated valve is responding properly. In other words, the control module may have a monitoring function and it knows if X value (percentage open) is commanded, coolant temperature is Y, and ambient temperature is Z, then the discharge sensor temperature should be within a certain range.

If out of range, a code would be set. The computer wouldn’t really know if the sensor was bad or the valve was acting up, so the pinpoint tests probably have you check both.

You’d never see such chassis fault codes unless using a dealer-level scan tool.

Once again, this is all conjecture on my part. And it’s definitely a moot point here, as the drain seems to be going through a different fuse.

 

I can't remember if I have the standard or premium sound system. Any way to tell? The system is stock. I do have a navigation system and an old school analog cell phone that came with the car new but service stopped years ago. Have an iPod radio adaptor I put in ~10 years back that I believe connected to the CD changer port. Is there a way to get to the radio wiring without taking the console off?

 

On my ‘02, the top of the face plate is labeled “Premium Sound”. If not present on a stock unit, that must be standard sound. That would also mean you don’t have to search for that second amplifier:





It’s been a while, but I don’t remember any trouble getting to the wiring. IIRC, the head unit and HVAC panel come out together, but it was easy. With a plastic pry bar (think cheap set from HF), pop off the two triangle pieces at the side and long piece across the bottom. This exposes some fasteners (Torx?) securing the whole shebang. There must have been some additional fasteners securing the head unit, but it was all easy to figure out with the trim removed.

 

Mine says Premium Sound too -- should have looked for that. I'll take the dash apart, but where would that second amplifier be?

 

The wiring diagram says “adjacent to steering column” and that’s it. Not extremely helpful.

I would suggest trying the head unit first. At least we know where that it. And it is much busier electronically, so is more likely to fall.