PHUNN
Senior Member
- Joined
- May 17, 2007
- Messages
- 132
- Reaction score
- 47
- Location
- UK South West Wales
- Your Mercedes
- SL350 September 2014 3500cc 7G Auto Iridium Silver R231
'Here we are again'.... Boot battery et al.
An update on the consequences of Deep Freeze which started on 13 January 2021.
Service and 'Star' session with my Covid nervous (and quite right too) Merc.specialist became due and passed without incident. No faults other than low voltage warnings which were to be expected after the completely flat boot battery syndrome.
So I brought the car home and washed it, paying, as usual, particular attention to the underside for road salt etc.
Finished the task, locked the car and retired indoors.
Later that evening noticed a strange noise. The engine cooling fan was running in the unattended, stone cold and still locked car!
And I could not get it to stop!!
Long story short; was forced to disconnect the boot battery and leave the car overnight.
The following day I discovered the top/lid on the engine bay fuse box was not properly fixed. Some of the visible fuses were wet.
Applied a borrowed hair dryer and after the necessary battery re-charging (again!) and re-connection, the problem has not (so far!) recurred.
Conclusion: (some being a re-statement of the bleeding obvious)
Check your manual key-hole boot lock is lubricated and works.
Do not let your batteries go flat, especially the boot battery which powers almost all the car.
If the engine cooling fan won't stop (and you don't know which fuse to pull) it's the boot battery which provides the power.
If the batteries must be disconnected then read the manual for the correct sequence (Negative first on disconnection. Positive first on re-connection).
The manual tells you about the need to reset the Time (my car recognised my mobile phone and swagged the time therefrom!) and mirrors (simply swing in and out on the button)
When reconnecting the boot battery make sure you have ALREADY closed the boot separator, even though this obstructs the view of the battery.
If the car is un-powered, pay attention when closing the doors and check the windows are sealed if you intend to leave the car outside.... If you press the top of the window glass when closing the unpowered door it is possible to persuade a reasonable fit.
When powering up the car after disconnection re-set the windows by running them up and down.
If the central locking seems to have failed, press the key 'unlock' button twice in quick succession. It may just be a 'reset syndrome'. That is what happened in my case. There was, it seems, nothing wrong with the Central Locking....merely the security procedure had been altered during the flat battery problem!
If the gear shift is stuck in 'Park' you can in an emergency sometimes wake it up by pumping the brake pedal or by holding down the brake pedal for some (10?) seconds.
If many 'cooks' have been 'under your bonnet' then check they have done the 'washing up'! Two garages and two AA chaps were involved in my saga. Somebody did not replace the fuse box properly....
An update on the consequences of Deep Freeze which started on 13 January 2021.
Service and 'Star' session with my Covid nervous (and quite right too) Merc.specialist became due and passed without incident. No faults other than low voltage warnings which were to be expected after the completely flat boot battery syndrome.
So I brought the car home and washed it, paying, as usual, particular attention to the underside for road salt etc.
Finished the task, locked the car and retired indoors.
Later that evening noticed a strange noise. The engine cooling fan was running in the unattended, stone cold and still locked car!
And I could not get it to stop!!
Long story short; was forced to disconnect the boot battery and leave the car overnight.
The following day I discovered the top/lid on the engine bay fuse box was not properly fixed. Some of the visible fuses were wet.
Applied a borrowed hair dryer and after the necessary battery re-charging (again!) and re-connection, the problem has not (so far!) recurred.
Conclusion: (some being a re-statement of the bleeding obvious)
Check your manual key-hole boot lock is lubricated and works.
Do not let your batteries go flat, especially the boot battery which powers almost all the car.
If the engine cooling fan won't stop (and you don't know which fuse to pull) it's the boot battery which provides the power.
If the batteries must be disconnected then read the manual for the correct sequence (Negative first on disconnection. Positive first on re-connection).
The manual tells you about the need to reset the Time (my car recognised my mobile phone and swagged the time therefrom!) and mirrors (simply swing in and out on the button)
When reconnecting the boot battery make sure you have ALREADY closed the boot separator, even though this obstructs the view of the battery.
If the car is un-powered, pay attention when closing the doors and check the windows are sealed if you intend to leave the car outside.... If you press the top of the window glass when closing the unpowered door it is possible to persuade a reasonable fit.
When powering up the car after disconnection re-set the windows by running them up and down.
If the central locking seems to have failed, press the key 'unlock' button twice in quick succession. It may just be a 'reset syndrome'. That is what happened in my case. There was, it seems, nothing wrong with the Central Locking....merely the security procedure had been altered during the flat battery problem!
If the gear shift is stuck in 'Park' you can in an emergency sometimes wake it up by pumping the brake pedal or by holding down the brake pedal for some (10?) seconds.
If many 'cooks' have been 'under your bonnet' then check they have done the 'washing up'! Two garages and two AA chaps were involved in my saga. Somebody did not replace the fuse box properly....
