Intermittent Battery warning light

[Lj1795]

Hi folks,

Battery warning light came on dash as driving home Wednesday night. Thursday morning it stayed off. Took it to a garage to check it over and they said the battery is fine, but obviously could be the alternator. Drove to work (25 miles) and it stayed off. As driving home last night the warning light came on for about 10 minutes and then went off again.

Any ideas?

 

[roadtripper]

What year and generation is your van (T6 and T6.1 have different electrics)

Do you have start/stop?

Any difficulty starting?

 

[Lj1795]

17 plate T6. It does have start stop. Van has started fine every day since I purchased it a year ago.

 

[roadtripper]

One possibility is a bad earth limiting current flow but if you are starting fine that's less likely.

Another possibility is that there is a fault in the negative shunt (either itself or the relatively delicate wiring to it) that means the BCM is not aware of the battery charge state - is your start stop actually working and the engine turns off?

What type of battery do you have and is it original? Can you post some pics of it?

I know you say you have had the battery tested but my first thought with electrical weirdness after obvious causes are eliminated is to start with a known good fresh battery.

 

[Lj1795]

Hi mate, thanks for the reply

When I drove it home and the light was off, the start stop works fine. Then when the warning light pops up, it says Error Start Stop on the dash.

I can’t see any history of the battery being replaced, have a full history of the vehicle as is an ex RAC so must be original.

 

[Dellmassive]

I'm wondering now if this is a LIN BUS wire problem from the battery shunt to the Alternator, a common issue on some vans.

If the LIN bus wire signal is lost the stop start error will be displayed, and the alternator will go into default output mode of 13.8v or something.

That may explain why the battery is not going flat.

Next step is to scan the van for error codes...

Carista is the easiest way to get that done, or vcds for a full scan.


.

Carista - How I Done It -

Carista - How I Done It - Part-1 Modern cars and vans are now technologically very advanced, gone are the old days of “points and condenser” or distributer caps, spark plug leads and the like. The Dark-Art of vehicle diagnostics was always something the main dealers wanted to keep very...

www.t6forum.com

.

VCDS / VagCom - How I Done It -

VCDS / VAGCOM - How I Done It - *********************************************** The current software version is : VCDS FULL Release V19.6 VCDS-Lite Release V1.2 VCDS-Beta V19.6.1 Click HERE for More Details Ross-Tech: VCDS: Downloads: Current Release and Manual...

www.t6forum.com

.




.

 

[Dellmassive]

More info on the LIN bus alternator thing here....

[Resolved] Start stop error/alternator charge issue ongoing

I've been chasing my tail with this issue for over a year now. Literally spent a couple of thousand trying to sort it and it still won't fix the issue. The garage I use are at a loss too. I have a start stop error on the dash. Also, if I start the van and let it idle, it won't charge the...

www.t6forum.com

.

 

[Lj1795]

Appreciate the reply, mate. I have an auto electrician coming to run a full diagnostics on the van next week. Shall post back in here with an update

 

[gilesjuk]

Other things to check, the belt which drives the alternator, tensioner and the voltage regulators on alternators can go.

 

[Lee8210]

Did you find the cause of the light coming on?
@Dellmassive We had our battery warning light light come on on the way back from a few days away, the van drove fine and when we turned off the engine nd started again it went out.
We have a Renogy 50A DC to DC charger and I wondered if this was tricking the van into thinking it wasn't charging the starter battery with enough amps as the house battery charged?

 

[Dellmassive]

Did you find the cause of the light coming on?
@Dellmassive We had our battery warning light light come on on the way back from a few days away, the van drove fine and when we turned off the engine nd started again it went out.
We have a Renogy 50A DC to DC charger and I wondered if this was tricking the van into thinking it wasn't charging the starter battery with enough amps as the house battery charged?

most a few pic of your setup, - has the light come back on?

damaged LIN bus wire from the Alternator can be know to cause that.

 

[Lee8210]

most a few pic of your setup, - has the light come back on?

damaged LIN bus wire from the Alternator can be know to cause that.

I think my problem could be the same as this post so I have posted more details there: Post in thread 'Help! No more electricity from the alternator? Or something else?' Help! No more electricity from the alternator? Or something else?