Flat Battery

[Ricardo48]

Hi, I have an intermitant problem, WhenI leave the car parked with electronic handbrake 'ON' the brake waring light stays perminantly ON.  Normaly it should stay on for about 5 minutes after locking vehicle.  Mine stays on and flattens the battery, the garage keeps telling me its a battery fault, have replaced bettery but fault still occurs.  Anyone got any ideas!!!!

[iantt]

i think the light staying on wont flatten the battery , but as the light is staying on, then theres an issue somewhere else that is draining battery, probably body control module.

can you leave handbrake off , possibly in gear, overnight and check if battery goes flat again or not?

[Ricardo48]

Hi, I have been leaving the electronic handbrake of over night and even for 2 to 3 days with no battery problems. I have had it back to the ford agent, they have plugged it into the computer and it shows up as no fault found. The problem is the fault is intermitant, and as the brake warning light has a delay of 5 to 10 minutes before going out, I feel that it has to be a relay or micro switch.

[MarcusB]

Is the 5-10 minute delay normal? Sounds excessive to me. The problem these days is most garages rely on the diagnostic computer for everything, the skills to have a OK and actually fault-find are lost. All them to get a skilled auto-electrician involved if they cannot find the fault, at their cost, as you've already paid for an unnecessary battery!

[Ricardo48]

Hi guy's it's been fixed the onboard computer was re-booted by the garage and the problem has gone away, for how long I have no idea.

I was also shown how to re-boot the computer.  'You start and stop the motor 4 times in quick succession', this apparently re sets the onboard computer.

[Ricardo48]

Hi , it's back again, just over one year and the same fault, yet agin the ford garage said it's the battery, NOT THIS TIME!!!So I have reset the computer as told by the garage and guess what !!! the Light doesn't go out, now I sit and wait untill 14 June  for the ford agents to look at it again (thank goodness for extended ford warranty).  I have been informed that it's all to do with the control module, so now I have to get them to change that, but most likely all they will do is re-boot the computer, and say it's fixed, and no doubt it will be fine for 15 months and be back again, well that will take it out of warranty.  Rant over, will keep you posted.

[Ricardo48]

Hi All, problem is solved so I am told by one switched on Tech at Ford who explained why my new battery ( 2016) was not able to cope with an S Max. Did any one know that when you change a Ford vehicle battery you can only fit a FORD battery Specific to that vehicle.   REASON :-  On the negative post connector of the battery there is a voltage detector unit so you must fit  a Ford 1/1863097 Battery ( Ford S Max Titanium S, 2.0 Litre TDI in my case). So if the battery is not showing a full charge this unit on the negative terminal  tells the vehicle computer that you have a low or flat battery and tell the computer to not allow the vehicle to start.  It can also throw up spurious faults and other warnings, as in my case with the brake light.