Is This Why My Auris Hybrid Battery Is Going Flat?

[RunningInPleasePass]

Why my Toyota Auris Hybrid Battery is going flat?

The reason suspected for the Battery going flat is a fault with the Hazard Warning control.

I have had a problem with the Battery in my Toyota Auris Excel Hybrid going flat twice, and my car has been into my local dealer for about a week to be tested.

I had a meeting with a Manager of Toyota Customer Product Support, he talked me through how Toyota deals with this type of problem, and what they suspect the problem is; I have tried to put down in writing what was explained to me as best I can.

First an explanation of the main items talked about as I understand them:

CAN bus (for Controller Area Network) is a car communication network that connects devices to each other around a car, a modern car will have a number of these networks.

ECU (for Electronic Control Unit) is a small computer, connected to the relevant CAN bus, reading and controlling devices connected to the CAN bus.

When the Hazard Warning Switch is operated it puts two signals onto the relevant CAN bus, the first signal alerts the ECU and tells it to wait for the second signal, this second signal instructs the ECU to turn on the Hazard Warning Lights.

It is possible for the Hazard Warning Switch to send the first signal and alert the ECU and instruct it to wait for the second signal, but not to send the second signal, the ECU is then left waiting, as the Hazard Warning Lights have to be able to operate all the time, even when the car is turned off and locked, so the ECU stays waiting all the time.

The power consumption of the ECU is nearly 600mA, the driver can stop, start, lock and unlock the car but this power consumption will be a constant drain, it is only when the car is off, and not charging the battery that this ECU power consumption will show itself, and if the car is off for a prolonged time will completely drain the battery.

Once the battery is flat, there is no power to the ECU, and when the battery is replaced or recharged the ECU has forgotten it is waiting for a signal from the Hazard Warning Switch, so the fault has gone.

To test for this fault, you have to measure the battery load with everything switched off to see if the 600mA ECU load is present, it’s also possible with specialist equipment plugged into the OBD socket, to check the status of the CAN bus and ECU.

At the moment the only way to remove this fault, is to turn the Hazard Warning Lights on then off, powering up then eventually down the ECU normally.

This problem can affect all MKII Auris Hybrids, all other models are not affected.

As I say this is only my best interpretation of the suspected fault as related to me, and I’m sure I’ve got some of it muddled up.

I have been assured that Toyota take these kinds of issues very seriously, and are working on a resolution to this problem with some urgency.

[geo13647]

Great find.

Makes sense, but something has to trigger the signal, personally, I've never used the hazards.

However, the alarm & smart start also share some of the same circuitry, sounds like it may be an ecu fault.

If one of the consumers (alarm, hazard or start or a.n other) hit the ecu & the faulty bit in the code is toggled,

Then the ecu will / may be triggered into an 'on' state with no other indication other than the excessive current draw.

If this is the case, then it's either a hardware fault (unlikely but not impossible) or a rogue bit of code in the ecu program

holding the wait for hazard (or other wait state ) high, this would force the ecu to be online all the time until a flat Battery or disconnection clears the faulty bit.

Unfortunately, this may take quite a bit of time to fix, ecu code is notoriously complex,

and is usually an old bit of core code with lots of patches. However Denso usually does good code..

Really, the only acceptable fix, would be a recall for a new (larger capacity) Battery, and an ecu re flash.

Hopefully Toyota will now start moving on this.

Good catch, well done.

Geo...

[RunningInPleasePass]

The manager when he explained it to me tried to recreate the fault with a CAN net breakout box plugged into the OBD socket, he suggested that just brushing the Hazard Warning Switch could cause this fault, we were unable to recreate at the time though.

[timberwolf]

A really good write-up and thanks for posting.

A continuous drain of 600mA would be 58 hours from a fully charges 35Ahr Battery - not what I would call a prolonged period to leave a car:-(

By signal did they mean CAN data Frame/message?

[Chris Dance]

Hi Kevin, Thanks for your informative write up on the Battery failure problem. When your Battery failed had you used the hazard warning? If not what caused your failure? It is good to know Toyota are concerned about the problem. Let us hope Toyota get it sorted. I think Toyota should put out a statement about this problem and let customers know when the problem is fixed. That would reassure customers like myself who may be interested in the purchase of an Auris.

[johalareewi]

Great find.

Makes sense, but something has to trigger the signal, personally, I've never used the hazards.

However, the alarm & smart start also share some of the same circuitry, sounds like it may be an ecu fault.

If the hazard switch is faulty, it could randomly generate the first signal without anything being pressed.

[crand5]

Hi Kevin, Thanks for your informative write up on the battery failure problem. When your battery failed had you used the hazard warning? If not what caused your failure? It is good to know Toyota are concerned about the problem. Let us hope Toyota get it sorted. I think Toyota should put out a statement about this problem and let customers know when the problem is fixed. That would reassure customers like myself who may be interested in the purchase of an Auris.

This is certainly making me think twice about ordering a new Auris Sports Tourer Hybrid as my next company car. The dealer I spoke with last week denied all knowledge of the issue !

[RunningInPleasePass]

A really good write-up and thanks for posting.

A continuous drain of 600mA would be 58 hours from a fully charges 35Ahr battery - not what I would call a prolonged period to leave a car:-(

By signal did they mean CAN data Frame/message?

The word "signal" is my interpretation of what I was told, it could well be the composition of the message that is causing the problem.

[RunningInPleasePass]

Hi Kevin, Thanks for your informative write up on the battery failure problem. When your battery failed had you used the hazard warning? If not what caused your failure? It is good to know Toyota are concerned about the problem. Let us hope Toyota get it sorted. I think Toyota should put out a statement about this problem and let customers know when the problem is fixed. That would reassure customers like myself who may be interested in the purchase of an Auris.

The one and only time I have used the Hazard Warning was when I first got the car, I tested all the bells and whistles.

The guy explaining it to me suggested you only had to brush the switch to cause the problem, you could even do it while cleaning the dash.

I fairness to Toyota I think they are still making sure that this is the problem, then, they have to find a solution, then I suppose we will hear from them.

[Fecn]

That sounds like a totally plausible cause for the Battery to be drained. I've worked on a number of embedded systems in the past (bike hire schemes with custom-made locking mechanisms etc) and have often been involved in debugging 'corner cases' such as this.

I'm one of the lucky ones who hasn't experienced any kind of problems with my Battery (yet), but I thought I'd chime in to say that I use my hazard lights every time I have to pull into my driveway (whilst I wait for the gate to open), so it's not the case that just using the hazard lights once in a while will cause this fault to present itself.

I'm very tempted to hook my data logger up to the Battery and see if I can produce the condition for myself now though :)

[RunningInPleasePass]

That sounds like a totally plausible cause for the battery to be drained. I've worked on a number of embedded systems in the past (bike hire schemes with custom-made locking mechanisms etc) and have often been involved in debugging 'corner cases' such as this.

I'm one of the lucky ones who hasn't experienced any kind of problems with my battery (yet), but I thought I'd chime in to say that I use my hazard lights every time I have to pull into my driveway (whilst I wait for the gate to open), so it's not the case that just using the hazard lights once in a while will cause this fault to present itself.

I'm very tempted to hook my data logger up to the battery and see if I can produce the condition for myself now though :)

The temporary fix for this problem, if you have it, is to operate the flashers when you park up, you then let the ECU go through the correct shut down procedure.

It would be really good if you connected your logger, then post your findings, it would be valuable information for us Auris owners.

[Mkuk0]

Just a thought, but surely locking/unlocking the car causes the hazards to flash as well, so could the operation of the central locking also send this rogue byte of data?

Not really as tech minded as you guys seem to be, so pardon me if I'm talking rubbish! :)

[timberwolf]

A really good write-up and thanks for posting.

A continuous drain of 600mA would be 58 hours from a fully charges 35Ahr battery - not what I would call a prolonged period to leave a car:-(

By signal did they mean CAN data Frame/message?

The word "signal" is my interpretation of what I was told, it could well be the composition of the message that is causing the problem.

Thanks. Sorry, I didn't mean to question your interpretation. I am amazed at how complex the transmission of a "signal" has become.

[RunningInPleasePass]

A really good write-up and thanks for posting.

A continuous drain of 600mA would be 58 hours from a fully charges 35Ahr battery - not what I would call a prolonged period to leave a car:-(

By signal did they mean CAN data Frame/message?

The word "signal" is my interpretation of what I was told, it could well be the composition of the message that is causing the problem.

Thanks. Sorry, I didn't mean to question your interpretation. I am amazed at how complex the transmission of a "signal" has become.

No need to apologise, I understand you are just trying to clarify what the problem is.

Your right, from the little I have read about these signals they seem very complicated, several fields, all of different bit lengths, each serving a different purpose, but from what I understand it's a very reliable way of controlling equipment.

Cars are getting more and more complex all the time, you need to be able to use a computer rather then a spanner to repair them these days!

[RunningInPleasePass]

For information the Honest John website has commented on this.

http://www.honestjohn.co.uk/carbycar/toyota/auris-2013/?section=good

[DCx]

Hi All,

Just to make you aware, I had a Civic SE iTec auto with all the usual boys toys which had failing Battery if left alone for 1 or 2 days. Honda dealer/Honda Swindon which I contacted said and one problem was that the electronic key entry system was not going to sleep and could draw upto 300ma in active state. It cost me more than £300 for a new ECU. Did it help NO. They finally change the Battery again under a slight pressure for me. No more problems for 2 years, must have been a bad batch of batteries with one cell failing.