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

**Disco4Dave** · 22nd August 2016, 10:41 AM

Originally Posted by 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.
...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 · 22nd August 2016, 11:49 AM

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

**scarry** · 22nd August 2016, 12:33 PM

Originally Posted by Tombie

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 · 22nd August 2016, 12:40 PM

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

**scarry** · 22nd August 2016, 01:16 PM

Originally Posted by Tombie

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** · 22nd August 2016, 03:47 PM

Originally Posted by Tombie

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 · 22nd August 2016, 08:27 PM

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

**Milton477** · 22nd August 2016, 09:39 PM

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** · 23rd August 2016, 07:28 AM

Originally Posted by 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.

I should have time to investigate this weekend. Will be interesting

Originally Posted by Milton477

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.

Originally Posted by Milton477

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** · 23rd August 2016, 07:40 AM

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

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

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