Battery Problem C Class/54/CDI/Saloon/Classic

[Fayyaz]

I have strange problem with battery.

It was perfect and never gave any trouble , one day I parked at work and when came back it refuse to respond at all, called AA and he jump started and said battery looks OK as it taking good charge. I drove 20 minutes to home and when I parked I checked and battery was ok, after 20-30 minutes it works fine again but next morning it was flat. Replaced the battery but it went flat again within 2-3 hours.

I started looking forums and found out there are many people with same problem.

In short.

I have replaced battery.
When battery is charged it gives 12.5** Volts, and 16+ Amps current drain when car is switched off

I have checked all fuses one by one at three different locations, I have disconnected many leads/jumpers as well, but current drain remain at 15-16 Amps. My local garage now have no clue and I am scared of huge bill by taking this to Mercedes.


Please let me know if you have any idea...

 

[whitenemesis]

Coolant boost heater. Very common for them to go short circuit and draw big current.

Most simply disconnect it and leave. They make bugger all difference to the speed of warming the engine anyway!

 

[Cole@MBS]

+1

 

[Fayyaz]

@whitenemesis thanks for your reply.

Would you please let me know exact location of this part.


Kind Regards

 

[television]

Look under front of engine and you will see a very thick electric cable going to the side of the engine, disconnect it and insulate it and tie it up.

 

[Fayyaz]

Engine

Sorry asking silly basic questions I hope you people don't mind this.

Here is engine picture, any suggestion about coolant booster heater cable..



Regards

 

[robparker]

The actual booster is under the inlet manifold on the side of the engine, just above the starter motor

 

[television]

Sorry asking silly basic questions I hope you people don't mind this.

Here is engine picture, any suggestion about coolant booster heater cable..

View attachment 28598

Regards

You have to go in from under the car and remove the under panel front