XSeries-forum

My car keeps coming up with Transmission fail mode. I have had it plugged in and the only error coming up on gearbox is
is code 151 - can brake information

Anyone decipher what this means for me?

What state is your battery in?  A low battery charge state or poor battery condition can trigger false warnings.  The 'CAN' is one of the car's communication data busses so one module may not be talking to another.

How old is your battery?

Try fully charging the battery and see if the errors keep returning?  As the mornings get colder, the days shorter and lights get used more and more it can very quickly find any dying battery.  There will be a spate of them as we get into Autumn and Winter.

Richard

Ok that sounds like the ideal problem.

Problem number 2:
Where is my battery? Is it under my spare wheel? I have an lpg tank there and got no idea how to take it out. Any way to test my battery with this in place?

The battery is in the boot at the left rear, and yes you need to get the LPG tank out to get at it!

There are two charging points under the bonnet.  See what voltage you get at them but make sure the car is 'asleep' and has not been run in the last 4 hours or you'll get a bad reading.  It should read at least 12.2V.

Richard

Im getting 12.14 volts. That ok?

That's about 50% charged and should be higher.  I take it that is without a charger having been used?  What's it like with the engine running?  Should be no lower than 13.6, ideally 14.2-14.4.

Fully charged it should be 12.65 - 12.8V.  The battery is usually an AGM type (Advanced Glass Mat) and they need the right external charger to correctly charge them. 

If you don't have a charger then get one that is AGM compatible.  A lot of folks on here use the CTEK range.  You need at least a 5A or higher (I use a 10A) in order to keep the recharge time around 12-hours or less.

Richard

Yes thats just been standing all day while been at work. I will check it with engine running. Would a 50% charged battery really effect my electrics like this?

Updated my earlier post with more info.

50% could indicate a low charge or bad battery.  These cars take a lot of battery energy to crank them so a low starting base won't help.  It can take a lot out of any battery and one that is more than 4 years old may be fading, after 6 years that gets more likely.  If you don't already then letting all the warning lights cycle on the dash before cranking allows the computers to boot up properly. 

It may not be the answer, but it's a good place to start (no pun intended) from.  The on board computers are sensitive to low volts and throw curve balls at wrong moments.. >:(

Richard

How much is a new battery likely to cost?

From BMW......a mortgage!

From someone like Eurocarparts around £100.

Bosch S3 for the 4.4 - 017 Battery.  There is an S5 alternative but it's more costly.

Richard

Bosch S5 100Ah is £126 with free delivery from GSF

Not too bad then, think I might just put a new one in anyway before the problems start, whatever I buy is likely to have an old one in I reckon

I bought a banner battery and mine starts like a mofo every time lol but it was about £175 so I would expect it to lol