Error codes U0001, U0103 & U0101 - Dealer says trailer power drain

[Disco4Dave]

Hi all,
I am looking for a sanity check from the forum brain's trust on some errors thrown by my car, and the diagnosis by the dealer. Sorry if it is long, but I want to recite anything which might be relevant.

Background
Our car is a 2016 D4 Landmark, bought new in June. It is unmodified, other than a Redarc tow controller that was fitted by the local LR dealer.
We tow a 25ish year old car trailer with old-school bulb type lights, with 2 x blinkers, 6 x tail/running lights, and 2 x stop lights. It is connected to the LR black socket via a 7-pin flat-to-round adaptor. All up, trailer with race car on-board weights less than 1800 kgs.

Incident
About a week ago, my dearest and I headed down to Phillip Island for a race meet, towing our race car on a trailer. This was the first long trip for our new D4, and it had approx 2,000 kms on the odo at the start of the trip. The week before it had towed the same trailer to Eastern Creek and back, about 30 mins each way, with no issues.

We left Hills District of Sydney on Thu morning, and after about an hour on the M2/M7/Hume we stopped at a rest stop just south of Camden for a leg stretch and for SWMBO to get a coffee :-) When I restarted the car after about 15 mins, there was one or more alarm noises, and the message centre displayed a number of warnings, Gearbox error, Park brake auto-release not available, etc

We called LR Assist, and they sent an NRMA serviceman. After clearing the faults, he disconnected the trailer plug, and was able to induce the same errors again on restarting the car.

With his agreement, I captured a photo of the errors reported on his console. They were:
U0001 Bus for high-speed CAN communication
U0103 Gear shift module - Last communication
U0101 TCM Lost communication

He diagnosed it as a "computer glitch", with no apparent mechanical fault, and after again clearing the errors, he advised us to proceed with care.

The same fault occurred another 4 times over the following days of the trip, always on restarting the car after a stop while towing. Fortunately another member of our team, traveling in convoy with us, had an OBDII tool which allowed us to verify that it was a repeat of the same errors, before clearing those errors. In 2 cases, there appeared to have been even more errors reported on the message centre (eg ABS failure), and the car would not allow shifting from park and dropped to access height.
In all cases, after clearing the errors, we were able to proceed, with no apparent ongoing issue.

Diagnosis
I left the car with the local LR dealer today, and showed them the screen-shot from the NRMA serviceman's console.
They have rung and reported that their technicians say this error is caused by the trailer overloaded the electrical connection from the car.

Does this sound realistic given the trailer has only lights, and that the error did occur once with the trailer electrically disconnected?

Thanks for reading :-)

[LandyAndy]

There is an issue where the BMS(Battery Management System) only charges when the vehicle on the "Over Run".
To check out how yours is charging get a ciggy lighter voltage meter from JayCar,around $20.
Go for a drive,note when your battery is charging.I will ALMOST bet my left nut that it is only charging at 12.3 to 12.5 whilst driving,when coasting downhill it will charge at the required 14.5V;););););) This is an economy feature,it will lead to poorly charged batteries.
I had the issue,and have Traxides SC160 dual battery system.When the vehicle was parked for several weeks I was getting "low battery start engine now" warnings.
Was talking to my shiny headed mate yesterday,his doesnt charge completely either.
Im guessing all your old school bulbs are using more power than the vehicle is making.
If you find you are getting the above charging you need to talk to your dealer,ask them to do the Gateway mudule software upgrade.Once done your alternator will charge at a much higher rate at idle and whilst driving,you will be able to note the difference on the voltage readout.
I havent had any issues since the software upgrade was done.
GOODLUCK
Andrew

[Mungus]

Lost communication with a few modules. Certainly could be battery voltage related and definitely at top of the list for checking especially if the first 2000k's were short trips followed by longer under load trips where the battery would not get sufficient charge. Very new battery though. Check the battery terminals are not loosely fitted. I'll ask this question each time due to my unfortunate 1 week old experience. Do you have rear aircon fitted?

[Graeme]

the message centre displayed a number of warnings, Gearbox error, Park brake auto-release not available

U0001 Bus for high-speed CAN communication
U0103 Gear shift module - Last communication
U0101 TCM Lost communication
My bet is a problem with the wiring to the gear selector or to the gearbox itself.

[Disco4Dave]

Thanks Andrew, Mungus & Graeme

Andrew, I have a multimeter and should be able to find a spare lighter plug, so I will try what you suggested and check the battery voltage during vehicle operation.

FWIW, when I collected the car yesterday the dealer reported that the battery had been tested and passed as "good", and they had done a "battery draw test" for 20 minutes, and "found 20 ma", so I am assuming that is a check of the parasitic drain on the battery.

Mungus, given the testing done yesterday by the dealer the battery terminals "should" be tight, but I will check them tonight anyway. Yes, the car does have rear air con. Why?

Graeme, a wiring problem is of course possible, but if so, why does this error only manifest on starting the car. An intermittent wiring problem would likely also cause faults at other times too?

I also plan to check my trailer plug and 7 pin round/flat adaptor, just to be sure there is no possibility of intermittent shorts there.

[LRD414]

Yes, the car does have rear air con. Why?
Rear a/c unit was slightly loose & caused an intermittent fault on his D4:
See http://www.aulro.com/afvb/l319-discovery-3-4/202141-no-brake-lts-hazards-etc-auto-h-lts-long-hard-reset-2.html for details.

Perhaps errors are only on start-up due to faulting during the gear selection process (Park to Drive), which only occurs at start-up. Note this is just my guess, not factual.

Cheers,
Scott

[Graeme]

Did the gear selector knob rise, did it get moved and did the car move off before the faults occurred? If the car moved off, how soon after did the faults occur?

[Disco4Dave]

Yikes Scott & Mungus,

That was a nasty fault, and congrats to the tech for solving that puzzle.

Scott, good idea, but my car faults almost immediately on starting, as soon as the engine fires, before I go anywhere near the gear selector.

[Graeme]

As the gear selector knob rises as soon as the engine has started, any faults in its operation could trigger an immediate fault. The fault could be as simple as an improperly fitted connector on the gear-shift module.

[Disco4Dave]

Just a quick report with some further information.

First a recap. Previously we had a bunch of faults thrown almost immediately after starting the car. This occurred at least 5 times on a trip from Sydney to Phillip Island and return, always on starting the car after a rest stop. We were towing our car trailer.

Last weekend we took the race car to Goulburn, with the same towing setup as previously. When taking a rest stop I would disconnect the trailer electrics from the car, and then leave it disconnected when restarting the car. Once the car was started and had been running for about 30 seconds, I would reconnect the trailer.

Out of 4 instances, there was no problem in 3 cases, but in one case the same errors were thrown immediately on reconnecting the trailer.

This suggests to me that the cause does lie with the trailer, as I can't it would be a voltage problem in that scenario, nor would a gear knob fault be the likely cause.

I plan to closely inspect all the wiring on the trailer, and probably replace some of the 8 tail/running lights with LEDs equivalents. I may also try disconnecting each of the powered light circuits in the trailer plug, leaving earth connected, then reconnecting them individually while trying to disconnect/reconnect the trailer to the car, and so narrow down which circuit is the likely culprit.

Any thoughts please?

[Disco4Dave]

There is an issue where the BMS(Battery Management System) only charges when the vehicle on the "Over Run".
To check out how yours is charging get a ciggy lighter voltage meter from JayCar,around $20.
Go for a drive,note when your battery is charging.I will ALMOST bet my left nut that it is only charging at 12.3 to 12.5 whilst driving,when coasting downhill it will charge at the required 14.5V;););););) This is an economy feature,it will lead to poorly charged batteries.
...snip...
Andrew

Andrew,

As you suggested I have been monitoring the voltage, although via an OBDII reader which reports both the "Control Module" voltage, and that at the OBDII port. Both values are usually within 0.2V.

I see what you mean about the voltage fluctuating during normal driving. I have seen between 12.3V and 15V, with the higher values evident when on over-run. This was without a trailer.

However, yesterday I took the trailer to Eastern Creek on Pennant Hills Road, M2 and M7, and the voltage was near constant at 14.8, with no evident variation when the engine was on load or over-run.

I wonder if the charging strategy is changed when a trailer is present?

[Tombie]

Charging strategy is based on demands..
Obviously a trailer will demand a bit extra..

[scarry]

Charging strategy is based on demands..
Obviously a trailer will demand a bit extra..

Tombie

A bit off topic,just wondering have you have ever checked your charging voltage while driving.Mine never goes above 13.9v ever.

I have been monitoring it for a while now.

Your vehicle is similar age and spec as mine.

Wondering if mine has a fault as an AGM battery needs higher than 14v,as the later model D4 seems to produce on occasions up to 15V.

[Tombie]

Has your CCF been set to AGM?
If it's set for Wet-Cell it will stay lower.

[scarry]

Has your CCF been set to AGM?
If it's set for Wet-Cell it will stay lower.

Really,

Thanks,you guys are so knowlegdeable:)

Suppose that means I need a tool,which I don't have.

[Disco4Dave]

Charging strategy is based on demands..
Obviously a trailer will demand a bit extra..
Yes, but without the trailer, when there is engine load the voltage drops to 12.5 or less, so if a trailer causes an increase in load, the results should be a lower voltage more often.
In this case when towing the trailer and traveling on suburban roads or with cruise control on expressways, regardless of load it stayed at 14.7 to 14.8

[Tombie]

Not quite... the vehicle will not let the battery go flat... so will charge accordingly.

[Milton477]

I recon the CanBus faults are a red herring & are caused by spikes or dips (noise) as a result of an intermittent 'short' in the trailer wiring. As you suggest, I'd be looking for a couple of errant strands of wire or loose connections maybe in the brake/tail light circuits. Do your trailer indication lamps work on your dash?

On the charging issue, my D4 starts out at 14.7v & then gradually drops to 14.4 , 14.2 & then finally 13.8 as the batteries charge over a couple of hours driving. This charge sequence is especially evident when the caravan is connected & the twin 120 AGM caravan batteries are low.

[Disco4Dave]

I recon the CanBus faults are a red herring & are caused by spikes or dips (noise) as a result of an intermittent 'short' in the trailer wiring. As you suggest, I'd be looking for a couple of errant strands of wire or loose connections maybe in the brake/tail light circuits.I should have time to investigate this weekend. Will be interesting


Do your trailer indication lamps work on your dash?
Yes the in-dash trailer indicator light works and the rear parking sensors are disabled when trailer is attached.


On the charging issue, my D4 starts out at 14.7v & then gradually drops to 14.4 , 14.2 & then finally 13.8 as the batteries charge over a couple of hours driving. This charge sequence is especially evident when the caravan is connected & the twin 120 AGM caravan batteries are low.
Good to know. Thanks

[PhilipA]

You do not mention brakes in your OP.
Does the trailer have electric brakes?
If so it could be a magnet leaking.
Regards Philip A

[Disco4Dave]

You do not mention brakes in your OP.
Does the trailer have electric brakes?
If so it could be a magnet leaking.
Regards Philip A
Hello Philip,
Yes it does have electric brakes, with a Redarc controller. I didn't install the controller and don't know from where it gets power.
This problem originally manifested when starting the car, so the car brakes would have been be applied, potentially also energising the trailer brakes. However, in the most recent case of this fault that occurred on re-connecting the trailer well after starting the car, the car brakes were not being applied.
When mucking about with the trailer this weekend I will measure the current drawn by the brakes, at idle and when energised.
Thanks

[Disco4Dave]

Well, just when I thought I had a handle on this problem, everything changes!
Last night on the way home from work, and so not towing a trailer, I stopped to refuel.
On restarting it threw the same bunch of errors as before, but as it has done only twice before there were additional cascading errors, and as a result it dropped down on the suspension and wouldn't allow the gear knob to be shifted from park.
Back to square one!

[Graeme]

On the assumption that the brake controller is permanently fitted, I would be checking the brake light feed to the brake controller. Can you unplug the controller for a while to see if the faults re-occur?

[Disco4Dave]

Another update, and hopefully my final post in this thread.
As suggested, I did diagnostics on the trailer electrics and checked the redarc install, without finding anything amiss.
Since then, over the last a month and a half, we have done a few trips totaling about 1000 kms while towing the trailer, plus another 1000ish kms on trips and commuting without the trailer, and had no errors.
I can't explain what caused the issues, nor why they have stopped, but am happy that some sort of equilibrium has been reached.
However, I have bought an IID Tool and will be ready to capture some relevant data if the problems recur.
Thanks everyone for your help and advice.

[Briar]

Hope this info may assist with extra ideas. I purchased my D4 on 30/6/2014. I had the dealer install a Red Arc Tow Pro brake controller. In Jan 2015 I got a couple of fault messages over a few days but disappeared on re-start.

On 28/2/2015 whist coming back from Sydney to Bathurst I started getting a multitude of fault messages. See attached video, (hope it works).

End result was after ringing Land Rover assist I had to get the D4 towed on a truck up to the LR dealer in Orange. This was a sad day.

Result of what was found. The technician at Orange found that the Red Arc Tow pro controller, the Earth Bolt that the controller had been attached to was not tight. All it was, was a loose Earth bolt that caused all the shown faults. Might be worth checking the Earth where the Tow Pro was attached. Never know.

115103

[Disco4Dave]

Result of what was found. The technician at Orange found that the Red Arc Tow pro controller, the Earth Bolt that the controller had been attached to was not tight. All it was, was a loose Earth bolt that caused all the shown faults. Might be worth checking the Earth where the Tow Pro was attached. Never know.
Thanks for that. Your video is very similar to the fault set I have seen a few times.
Sounds like an earthing check is needed!