2015 D4 Blank infotainment screen PLUS battery drain

[BigSud]

Hi all,

This is my first "proper" post - seeking insight into a weird problem - although a couple of years back I sought advice on changing my SDV6 inlet manifolds. To the excellent advice I found for that job, I would add "buy crows-foot spanners".

This particular query is the first of three, the others of which I'll get to once I've solved the screen/battery issue, but in the interests of good storytelling they are:

1) Infotainment screen dead, 1.2A drain
2) Preventive maintenance main & big-end bearing replacement on the SDV6?
3) Which motor would be the best upgrade if there is a lot of towing in our future (there is) - a TDV8 (which one?) or should we wait and see about the "new" Ranger V6?

Some history of the car, which we intend to keep for another 10 years at least. Ours is a 2015 NZ-new Discovery 4 HSE SDV6 with the factory Safari and Winter packs fitted, meaning - as far as I can ascertain - it has the big alloy bash guard on the front, a snorkel and driving lights, plus heated steering wheel and side mirrors, plus the rear climate control. We're the second owners, having bought it in 2017 with 103 km on it, just out of warranty. It's now covered 233 km, until recently fairly reliably. The only issues have been the handbrake module (replaced under extended warranty) and the inlet manifolds. 103 km in 2 years is a LOT of driving, which we think were "hot miles" with relatively fewer cold starts than you'd need to see that mileage over five or ten years.

Last year, at about 130,000 km, the HP fuel pump let go. Because we were 500 km from home, we had little choice but for the AA to take it to a local European specialist. They did the diagnosis, lifted the body, and replaced the HPFP. The car fought them every step of the way, but eventually all was fixed and it was running well. In hindsight - such a useful thing - I would have had it freighted home and invested in a two-post hoist and did the job myself.

When I picked it up, the infotainment screen wasn't working - although the digitiser still was as it beeped when pressed. They checked the fuses and nothing was amiss, and said it had never been working for them. I accepted it because after months of waiting, plus travel to get it - I just wanted it back and could sort out a dead screen later. Maybe it's a good excuse to do one of those CarPlay upgrades

The next morning, the battery didn't have enough juice to start the car. AA arrived, declared that 10 years was a good run out of the original battery, so I bought another AGM matching the original JLR one. Next morning it started OK. But three days later it didn't.

Fast forward to now, a few months later. It's had two "failed to proceed" incidents, both related to the power supply to the LPFP, so I've both replaced the LPFP itself AND bypassed the entire feed from the fusebox as somewhere in one of the three connectors along the way it was losing voltage. Such things often happen when something is disturbed by a major effort like removing the body - I've seen it with other cars we've owned - and there are some silly details on the D4 that don't help with that.

But to come back onto the main topic of the thread, I think that in the process of removing and replacing, then removing again (don't ask) and replacing the body to get the engine to fire something has been fried in either the infotainment screen or the amp that feeds it. I've found the circuit that's draining the battery, and its Fuse 1 (in the upper passenger compartment fuse box) for the screen. It drains up to 1.2 A with the ignition off and the car asleep. With the screen unplugged, the drain stops. Using a MOST bypass loop on the screen does not affect the drain. Substituting an apparently good used screen does not affect the drain.

Apart from the screen not working, up until recently almost everything else WAS working.. The Bluetooth audio, which is the only audio we ever use - was still functioning, right up until I ran my phone over and had to pair the new one. Which is impossible when the screen doesn't work. The radio still works and the amplifier still...amplifies. The audio-related steering wheel controls do not work.

My current theory is that some capacitor or MOSFET in the amp has been fried by the body off/on/off/on palaver, and its not allowing the screen to turn off - nor is feeding it anything. Question 1 - does this seem plausible?

So I stripped out everything again to get a look at the label on the amp - see the pic below.

Amp label.jpg


There are LOADS of these available on eBay, and they seem to all differ in the last two letters of the version number - in my case CF6N-18C815 - MK. I'm assuming that that this is some sort of model/country signifier, but further I'm assuming that unless I want the (useless) SatNav and (boring) radio functions to work, swapping in a functional one of these might solve the battery drain problem AND restore the screen function. Question 2 - am I right here?

As far as I can tell, the Holder Of The Knowledge is Old Jaguar - AND it seems he also knows about engine swaps. Would that be right?

Question 3 - what have I missed?

I'm not a fan of the Parts Cannon, so if there's a known problem that twenty minutes with the soldering iron and a DVM could fix, that's much better for all concerned.

Thanks for reading this far. I'll set myself up a signature soon. For now, this is my fifth Land Rover - an RRC, 2 x P38s (all gone) and I currently have a 1954 S1 86" which is an atmospheric corrosion experiment. Which is fitting because I used to be a corrosion scientist. That makes the three additional Alfa Romeos cluttering up the place particularly ironic doesn't it?

Chris
In Kapiti, New Zealand.

[BradC]

I'm not sure of any similarity between the later D4 and the D3. I have a D3, but certainly my 2010 D4 wiring diagram shows they were still similar at that point.

There is an "infotainment" relay which controls power to the screen and amplifier. This is run by the audio head unit (radio) and should turn off power to those devices "X" number of minutes after the car is shut down. From memory, the head is also the MOST bus master.

So in the D3 the head turns on the infotainment relay which powers up the rest of the system. The display then powers up and displays it's boot screen. This remains on until the head unit fires up the MOST bus and tells everything to switch on. The head also manages the steering wheel controls.

If the infotainment relay remains powered, the system remains on but idle.

So it is entirely possible that an issue with the head unit can cause your symptoms.

Now, again the latest docs I have are for a 2010 D4, so yours might be entirely different and this post entirely irrelevant.

[BigSud]

Many thanks for that, and the insight into the MOST system operation.

"If the infotainment relay remains powered, the system remains on but idle." That could well be what's going on.

I'm also happy to learn that the amp is the master in the system - it reinforces your point above, AND also might explain the blank (but presumably not dead) screen.

Many thanks for that!

Who else has working knowledge of how the media-oriented system works?

Chris

[BradC]

I'm also happy to learn that the amp is the master in the system

No, not the amp. The radio head unit in the dash is the MOST master. It also controls the infotainment relay.

[Cambo_oldjaguar]

No actually in 2012MY onward the touchscreen is the MOST master module, in earlier models it’s the head unit.

[Cambo_oldjaguar]

The small grey fusebox behind the upper glovebox is the "Quiescent Control Module" which powers all the infotainment system and climate control, and also the Battery Monitor / Charging Control.

It's meant to power off the infotainment after a time.

It's controlled by a digital signal (LIN) from the Gateway Module (GWM).

I think your faults lay somewhere with the GWM &/or the Quiescent Control Module.

If there is constant power at fuse 1, but not the other fuses in that module, then I'd be looking for a replacement, something gone wrong with it internally.

[BigSud]

Many thanks for that, it's a bit of an eye-opener - and does point to how complex some of these systems can be without a control logic diagram to refer to. What the group knows collectively is all from hard-won experience and I'm very grateful for that.

I've been wondering about the quiescent control module since it's job does seem to be to prevent what I'm experiencing. Yes, it's only fuse 1 that's still powered up and that's the screen and infotainment 15A fuse.

If there's a fault in that module - or the gateway module (that seems to be some sort of router?) - that would explain the parasitic loss.

That would mean then that the lack of screen function is a different problem and originates with the head unit? Does anyone know if they're prone to failing in this way? And if so, are they fixable by someone competent with a soldering iron?

As I said above, it should be relatively easy to substitute in a used one (I'm NOT paying insane LR $$ for a new one, given its a FORD part made by Sony or JVC or somesuch) if they only differ in the regional frills like satnav and radio bands. Does the group have any insight about that?

And a final question while I'm cheekily taking your time...are any of these modules coded to the car, like in some Porsches or BMWs?

Many thanks,
Chris

[BigSud]

Thanks all for your help, and I agree it looks like either the quiescent current module (a replacement is on the way) or the gateway module.

I have the 4,000 page online repair manual, and it doesn't refer to the gateway module by that name anywhere. The Body Control Module is ALSO not called out by that name anywhere in the manual, although there are AULRO posts that seem to suggest the the GWM some sort of subset of the BCM.

I've owned and fixed two P38 Range Rovers, so I have a healthy fear of BCMs. PTSD, some might say.

I have taken the instruments out from behind the steering wheel - which is where the GWM is said to live, but there's nothing in there apart from the loom tucked behind the magnesium cross-beam. It's almost impossible to get a look up into the area below the instruments/above the steering column and pedals, but is this where it lives?

I'd like to get my eyeballs on the one that's in the car, so I can order the exact right part - but its in hiding.

Youtube is usually great for this sort of thing, but even PowerfulUK or LR Time haven't had to untangle this particular problem yet.

All the best,
Chris

[BigSud]

Just a progress update to this one.

I've replaced the quiescent current module (made no difference to either the function of the screen OR the parasitic battery drain.

I replaced the screen and it again made no difference to either of the original problems so I reinstalled the original.

I replaced the Nav/DVD head unit and again it made no difference. So I swapped the replacement screen back in and LO! it works.

So that's a big step forward - now we can connect to the Bluetooth audio, use the reversing camera and (and I'm amazed at how irritating this has been) set the clock!

However - the 300 mA battery drain remains.

From Old Jaguar's original advice the only thing I haven't replaced is the gateway module - primarily because I can't find it. Advice on that please

But if we assume that it's not the GWM, are there any insights into what might be going on?

Cheers
Chris

[BigSud]

Some more digging has uncovered a couple of oddities - to me, anyway. Others may already know this!

In trying to track down the remaining 330 mA drain, now that the screen and DVD/Nav units have been replaced and work properly, I tried to find what ELSE was on the circuit governed by the quiescent current module (at the back of the upper glovebox).

Nowhere in the 9000-odd page online workshop manual, or the accompanying wiring diagrams, is that module mentioned. There IS a "battery protection" relay but that's not an electronic module and only has a couple of feeds - so is clearly not what I was trying to find.

But the wiring diagram DID show both the amplifier, and phone module. The former located under the driver's seat, and the latter in the loadspace behind the right had trim. So I found the torx bits and the trim tool and went looking.

On a 2015 D4 - VIN 61888 - the amp is NOT under the driver's seat. And there IS no phone module that I could find. Instead, the amp is behind the rear trim - see pix. And disconnecting it - or the MOST bus - didn't fix the drain.

IMG_0221.jpg IMG_0222.jpg

I suspect that as technology has improved, the number of random modules needed has reduced, meaning the amp can be moved to somewhere less likely to be damaged by spilled coffee or a misjudged river crossing. But as a result of that, all of the previous reference material is out of date.

Two questions:
1) The online resources I have access to are clearly useless, and (worse) are possibly misleading. I know that there is some sort of paid online access directly into JLR's online resources where you can find USEFUL information about your specific car - does anyone here know how that works, and whether it's worth it?

2) Where in the car is the gateway module? That's the only remaining "sensible" place to check to find the current drain. I'm starting to suspect that it may be the part that gets suspended in space with a skyhook while the rest of the car is built around it. I've dug fairly deeply and so far haven't found it.

Cheers
Chris