I have been having major issues with the X350 not charging properly for some months, it wavers between 11.5 and 12.2 when cold and remains like that. If I switch off when warm and restart, it wavers between 12.8 to 13.7 volts? Quite what being warm and/or restarting does I don't know?

I recently left the car at the Airport for a week. On my return at 12:15 midnight, the battery was completely flat, I needed to manually unlock the car. I hooked up my booster to the battery and got the engine started, all seemed Ok, except (of course) the battery wasn't charging properly. I had warning lights all over the dash, the radio screen kept going off... coming on.. going off etc. The headlights (1am in the morning) kept going off and on, Gearbox Fault, Oil Light, Battery light... you name it!
I stopped at a motorway service station, managed to get the positive lead off the battery and touched it on to the Negative to reset and Modules, reconnected the battery, and had to use the booster again. I got it started and a lot of the warning messages disappeared, but now it was warm it started charging at over 12 volts so I kept going on the 2 hour jouney home. Next morning I tried to start it, the turnover was very slugish, it failed to start and again caused a load of warning lights to appear (I also got a 'Press footbrake and emergency brake together'?).

I bit the bullet and purchased a new alternator and a starter motor, I had the battery checked and made sure the Earth points near the battery were sound. I also checked all the cables and connections to the large fuses in the boot/trunk, all Ok, as was the power cable from the battery to the connection point under the right side front of the car and onto the alternator. When I fitted the new Alternator and Starter Motor, I made sure the connections were clean and tightened up. Finally I checked any amperage being used with everything turned off. very little was being drawn. Unfortunately, all the checks and the fitting of new parts made no difference whatsoever.. In addition, I now have an even bigger problem! I am now getting a 'Gear Load 3-4' issue, DTC Code P0783, plus a B1676 Battery Voltage Out of Range code, and the same B1676 code DTC from the 'Rear ECU'. Again, turning off the ignition (and assuming there's enough life in the battery to restart) the Gear Load and other faults disappear until I drive the car, it won't change from 3rd to 4th, and tends to 'thump' into gears rather than the usual smooth changes... eventually the faults reappear. BTW, clearing the codes deosn't stop the thumping into gear and eventually brings up the same Gear Load 3-4 error.

It appears I did some damage when getting the car going with the booster and running it without it charging. But I don't have a clue where to start sorting out what's wrong. It seems I need to concentrate on getting the car charging properly, then set about resolving the Gearbox issue?

Finally, as I have the Jaguar SDD software, can anyone tell me if the charging rate is a setting in the ECU, or somewhere else? If I had hair I would be pulling it out... I really am relying on the good people of this forum to guide me through these issues. If anyone can help please chip in with your thoughts... they will be much appreciated.
Paul

 

I’m no expert but sounds like a bad earth somewhere

 

Hi Paul,

Thin white powdery aluminum oxide corrosion on ground points and battery power connections can cause more trouble than you can imagine, but it sounds like you've cleaned most of the prime suspects. Battery charging voltage is managed by the ECM, and a common problem is water ingress into the ECM electrical connector, which is below the cabin air filter housing, accessed from the engine bay. The main ground point referenced by the ECM is also nearby on the right inner fender, covered by the plastic trim.

You said that you had the battery tested - was it testd on a good conductance analyzer that could test the battery's actual Cold Cranking Amps, Amp Hour capacity and State of Health and detect a dead cell?

I am attaching the battery charging strategy explanation from the Jaguar documentation and the Electrical Guide, which shows the battery/starter/alternator/ECM circuits on pdf page 59.

Cheers,

Don

 

Hi Don B, many thanks for your reply... it's becoming a bit of a devil this one!
Yes, I had the battery tested fully, it is only 5 months old but it tested out Ok, it's a large YUASA 100 Ah battery. Having read your comments I believe the problem is likely with the ECM, just to make sure, when you refer to the ground referenced by the ECM being near the right inner fender, idoes that change to the left side if the car is RHD? The reason I'm asking this is that I changed the cabin filter not so long ago, mine being on the left side (my passenger side).

I did find a TSB deep in my file system (307-00 JTB00072v2 Transmission DTCs P0780 to P0785) which covers the P0783 I have. It lists a test/repair procedure that I might be able to access on my SDD system? It mentions using the IDS Software, but I understand that the SDD software captures any IDS codes?

I also think it prudent to check out the ECM, I can get another from a local JLR breakers if absolutely necessary, but I would take a snapshot of my setup as a backup to be safe. I would much prefer not to go down the route of changing the ECM thought unless theres no option. What I have never been able to find is any kind of user manual for the SDD Software, or the IDS for that matter!

I have also spoken to someone local here in the UK who advised me there are a few ground points behind the headlights that are notorious for causing problems... what I need is a full list and check every one I think lol. many thanks for your input, I will report back as soon as anything goes forwards or backwards lol
Paul

 

After years experience with Jaguars, this is what I would do first. I would buy a new battery after it was completely charged before I put it in the car. Then if this did not work proceed with what you are doing.

 

Hi Paul,

regarding your last point, Don has already sent you the electrical guide in a previous post, and in it you will find were all ground points are located on page 22.

Best regards,

Thomas

 

My read on this thread is you're jumping around and jumping ahead to issues that are likely going to be resolved by fixing the initial low voltage. I'm not sure why you replaced the starter? But that's water under the bridge. I would not worry one iota about the transmission until the system voltage is at >13vdc with the engine running. The ECM from a junkyard is not going to help and probably the last thing to actually fail, you won't be able to code a used ECM to your car. Sorry for sounding harsh here--but I feel like I'm watching a disaster in slow motion as parts are thrown at a relatively simple issue. Don't throw parts at the car until a thorough diagnosis has been completed--with a scope you can check to see what signals the alternator is receiving.

First and foremost, resolve the low charging voltage. Per the TSB Don posted, the alternator will put out 13.6vdc minimum, or 15.3vdc if the ECM senses the engine/ambient is cold. At what point are you measuring the low charging voltage? At the battery itself? I would check the output voltage at the alternator B+ terminal to see if the issue is the alternator (it is very possible a replacement part is bad out of the box), or if there's a voltage drop issue between the alternator and the battery. My suspicion would be on the large ground strap between the engine and the body.

Grounds behind the headlights are not going to be the issue here. There is an ECM ground next to the ECM where the EMC and TCM connect to the inner fender--maybe, but doubtful. The ground at the battery to the trunk (2 of them) may be worth checking.

Also note, when you are measuring voltages, use the same ground point as the device under test. E.g. when you measure battery voltage, put the meter ground on the negative post. You can see if you get a different result grounding the meter directly to a body point. Same with the alternator, use the engine block as the meter ground.

 

Hats off to Dkirk, Don B, and mhamilton, I took your advice and started checking the earth points, at the battery, battery to chassis, and chassis to engine/gearbox. Couldn't find anything at first so decided to go over each connection with a toothcomb! It turned out to be a hairline crack on the battery negative cable, the round bit that clamps on to the battery post. Either I, or someone else previously had over-tightened it and caused the issue. Replaced with a new one and instantly I was driving at 14.5 volts, idling at 13.8, I can honestly say the car has never started with the spin-over speed it does now. I know how many people say the issues that can occur with a bad earth, but I hadn't realised just how much until I witnessed it first hand. At least the car has a new alternator and starter that should last a while!

Like mhamilton also suggested, there could also be underlying problems with other devices (gearbox included) that were a result of the low voltage. Doubrtless there will be a ton of DTCs listed that I will sort out and see where we are at that point... I will come back with updates on those issues.

One question. Don B mentioned that the voltage is controlled from the ECM on page 59 of the pdf and I can see the drawing and connections to the ECM. But mine is the 2.7V6 on Fig.2.3 that shows a PCM (Powertrain Control Module) not ECM? For my piece of mind and future reference can anyone explain the difference(s) please, and could any differences influence the P0783 Gear Load 3-4 error?
Paul

 

So glad to hear you resolved the charging issue without launching the parts cannon!

PCM = Powertrain Control Module, ECM = Engine Control Module. Why Jag differentiates on diesel vs petrol? Not a clue... there appears to be no difference in this application. In the old days, "PCM" was used as the terminology when the engine and transmission were controlled by a single module. Our cars have a separate transmission control module (TCM) inside the gearbox. The more modern nomenclature is to use "ECM" to define a control just for the engine, and "TCM" for the transmission control. Again, no difference exists on the x350 platform. Probably some oversight/typo/holdover from a different platform.

The P0783 has scant information in the service info, just "Transmission mechanical failure." I seriously doubt that occurred because of low voltage. At this point, I would disconnect the battery make sure it's fully charged, let the car stay without power for an hour or two. Reconnect the battery, clear any TCM or ECM fault codes that may remain, and assess any codes that come back. Do you have a scan tool that can access the TCM and clear codes there? A standard OBDII reader may not be able to do this and some codes (once set) will not clear even with a battery disconnect.

 

Hi mhamilton, many thanks again for the clarification re the Modules. Yes, I have a Autel scanner that can read and clear the TCM, PCM, and the ECM DTCs, if required I also have the Jaguar SDD software. I havent done too much with either of these devices as the battery was previously too low to leave the ignition on etc etc...
I have tried clearing the codes, however, I discovered a couple of points today:...
1) I live near the sea where there's a very steep hill to climb away from the sea front, at the top I suddenly got a load of blue smoke from under the car. I recognised the colour and smell as ATF burniing on the exhaust (as this leaked a few years ago).
2) If the 'Gear Fault' message comes on, it won't change gear from 3rd to 4th. However, if I stop, switch off, then restart, the error disappears and I can accelerate fairly fast and achieve all gears... even though between 3rd and 4th the engine revs higher then changes through all gears? If I continue running between 3rd and 4th, say in traffic, it causes the error to appear.

My thoughts are that the gearbox could be low on ATF and needs topping up? As it hasn't been changed since it used to leak I thought a new filter/gasket/fresh ATF wouldn't go amiss... what do you think? I could also have a good clean around with the pan off, I am unsure if there are any things I could check for!.
From this my question is: would low ATF level cause the symptoms I'm having, and bring up the 'Gear Fault' message? Your input with all this is priceless, thank you so much!!
Paul

 

just doing some research and found this on Google...

Jaguar P0783 means a 3-4 Shift Malfunction, indicating the Powertrain Control Module (PCM) detects an issue with the transmission failing to shift smoothly from third to fourth gear, often causing revs to climb without engaging fourth gear, triggering a "Transmission Fault" message. Common causes include low transmission fluid, faulty shift solenoids, worn clutch packs, a bad valve body, or issues with the Transmission Control Module (TCM) itself, requiring checks of fluid, seals, and potentially internal repairs like ZF gearbox kits or solenoid replacements.
This video provides a quick guide to understanding the P0783 engine code:

2 things here, the "climbing engine revs" (exactly what happens with mine) and "low transmission fluid"
Paul

 

Hi Paul,

I can't recall whether anyone has mentioned in your thread that a very common cause of random transmission-related DTCs is transmission fluid contamination of the electrical connector at the rear end of the transmission. This connector is sealed by rubber O-rings on the cylindrical plastic sleeve around the connector. As these seals harden and leak over time, transmission fluid seeps onto the connector pins, causing interruptions in communication between the TCM inside the transmission (the "Mechatronic" in ZF terminology) and the ECM.

The connector is a little awkward to get to, but you'll find it high on the rear end of the transmission. There is a black plastic retaining collar with two tabs or wings that help you rotate the collar counterclockwise when viewed from the rear. Once loosened, you can carefully withdraw the harness connector from the transmission connector. Inspect the harness connector for signs of oily fluid, and use a mirror and bright light to inspect the transmission connector. Any wetness at all indicats failed seals on the connector sleeve.

Replacing the sleeve is not too difficult, but it does require dropping the transmission pan/filter. If you find any wetness in the connector, plan on replacing the pan/filter and valve body bridge seal and tubular seals and replacing the transmission fluid while you're at it (In the U.S., Motorcraft Mercon SP is usually the most affordable correct fluid if you can find it, but in the U.K. you may need to use ZF Lifeguard 6).

Cheers,

Don

 

Hi Don B, many thanks for your input. What you have described could well answer why I got the preverbial blue smoke after climbing that steep hill... the leaked fluid would run out of the connector and on to the exhaust? It would also add to the 'Low Fluid' theory causing transmission errors!
As I plan to change the filter and top up the fluid it has to be worth renewing these seals, I will look up the part numbers and see if I can get them from SNG Barrett. Many thanks Don...
Paul

 

Hi again Don. Is this what I'm looking for?


Paul

 

Yes, that is the connector sleeve. If you find wetness inside, it should be replaced, and that will be the right time to also replace the plastic transmission pan/filter assembly and the rubber seals between the valve body and gearbox that harden and leak, causing loss of pressure and shift problems.

Let us know what you find inside the connector and if you need to replace it we'll advise you on parts.

Cheers,

Don

 

For the sake of £16 it's worth just going ahead and replacing it, but I will report on what I find when I remove the old sleeve. Before I order it, can you help with the other seals' parts/numbers and I can order all together. This thread has been so useful
Paul

 

Send me your VIN via Private Message and tonight I will try to look up correct part numbers for you.

Cheers,

Don

 

Paul,

Thank you for sending me your VIN via PM. Unfortunately, the VIN decoder at Jaguar Forums could not decode it, but that seems to be a common problem with non-North America VINs. I did find a U.K. VIN decoder that confirmed your car is a 2006 XJ Sovereign TDVI Automatic.

We did not get the diesels in the U.S., but from what I can tell, you should have the ZF 6HP26 6-speed automatic transmission. You can confirm this by locating the serial number tag on the side of your transmission. It would be helpful for confirming parts if you can record the serial number and give it to the seller from whom you purchase your parts.

From my records, here are the Jaguar and ZF part numbers, as well as a few for Eriksson, which is a major supplier to professional transmission repair shops (at least in the U.S.).

Sump Pan/Filter: Jaguar P/N: C2C6715 supersedes to C2C38963 ZF P/N 03.010 Eriksson Pan P/N: 1068-298-075

NOTE: The "genuine ZF" pans are made by IBS Filtran GmbH (and are made of LANXESS Durethan AKV 35 H2.0 polymer, if you're interested)

Electrical Connector Sleeve: Jaguar P/N: C2C9645 ZF P/N: 27.520 Eriksson Sleeve P/N: 0501-216-272

Bushing / Tubular Seal / Sealing Sleeve, VB to Case: Jaguar P/N: C2C9653 ZF P/N: 01.050 (NOTE: 2 are required)

Bushing / Tubular Seal / Sealing Sleeve, VB to Case: Jaguar P/N: C2C9654 ZF P/N: 01.060

Bushing / Tubular Seal / Sealing Sleeve, VB to Case: Jaguar P/N: C2C9655 ZF P/N: 01.064

Adapter / Bridge Seal / Rubber Spacer Gasket, VB to Case: Jaguar P/N: C2C12379 ZF P/N: 27.460

Checking various Jaguar parts suppliers, including SNG Barratt, prices seem to be very high on some of these parts. You may save a lot of money if you can find a specialist in ZF transmission parts. Perhaps one of our U.K. members will know of such a firm.

Regardless of where you purchase the parts, give the seller your VIN and ask if they can confirm that the above part numbers are correct. The 6HP transmissions used in BMWs use a different Adapter/Bridge Seal that is 1.0 mm taller than the one used in Jaguars and will crush and not seal properly. I am attaching a couple documents that may be helpful. I have dozens of 6HP documents including complete repair manuals, but those are too large to attach to posts at JF.

Regarding fluid, while many fluid makers offer products claimed to be "suitable" for use in the 6HP, the only three fluids we have proven to be correct are ZF Lifeguard 6, Shell M1375.4 and Ford Motorcraft Mercon SP. Ravenol has subsequently developed their ATF 6HP Fluid, which was purportedly developed specifically for the 6HP transmissions. I have not fully researched this fluid, but the one caution I have noticed is that Ravenol claims this fluid is backward-compatible for ZF 5- and 4-speed gearboxes, which is implausible since the fluids ZF specifies for those transmissions have significantly higher viscosities than Lifeguard 6. So try the Ravenol at your own risk.

Before you order all these parts, I highly recommend that you check that electrical connector. Finding any oily wetness in the connector will be good news, since it could very well be the cause of your shift code. If the connector is dry, I would personally conduct further troubleshooting before going to the trouble to change the fluid, pan, valve body seals and electrical connector sleeve.

Regarding the P0783 DTC, here is the official definition and published possible causes:



The ECM torque signal originates with the Mass Air Flow Sensor (MAFS), then is communicated by the ECM to the TCM. Any interruption in this communication could trigger P0783, so either water/corrosion on the ECM connector or transmission fluid in the transmission connector could be causes. Transmission mechanical failure is rare but not impossible.

I forgot to answer your earlier question - yes, I do think that on your RHD car the ECM will be behind your glovebox, and the electrical connector will be accessed in the engine bay under the cabin air microfilter housing, and the main ground referenced by the ECM will be on your left inner fender under the plastic trim.

Cheers,

Don

 

Looks like Don gave you plenty of excellent advise--not a whole lot I can add. Yes it sounds like your transmission is slipping in gear and this issue is separate from the low voltage issue. Agree 100% the first step is to check the fluid level. Lots of threads on this already, vehicle needs to be actually level on a lift and you monitor trans fluid temp with a scan tool. You'll also need a fill pump as the plug is a royal PIA to access.

The leak at the transmision sleeve connector is very common, and would indeed leak more on a steep incline. If it's leaking enough to smoke up on the exhaust you are probably low on fluid. Note that to change the sleeve the pan has to be dropped, so it's a bit more involved than just the $30 sleeve itself. Probably about USD $300 in parts. Stick with OEM only on ZF transmissions.

I recently did a deep refresh on my 6HP gearbox, total cost of around USD $750. BUt I had no faults prior, just some harsh shifts. You can take a look here https://www.jaguarforums.com/forum/x...-6hp26-292894/

My recommendation would be to check and refill the trans to the correct level, evaluate the driving for a while and make sure there's no permanent damage and codes do not return. Then if good, go through and replace the sleeve, service, etc.

 

Hello Don, have to say a massive thank you for your reply, absolutely full of details easily missed without your research... thank you so much.

I have the Sump Pan/Filter, that arrived today. I will check out the prices of the part numbers you got for me, and report back after I have the parts, and I have got the car on a lift to carry out the work.

Only thing I'm unsure about is 'Reduce the Throttle Angle until the torque converter locks' and hold it for one minute. Is that when the box is in 6th? I understand the principle of the lock up but never done it before and don't know what to expect/look for?
Paul