Power drain 2001 G500
My 2001 G500 has developed an irritaing fault of dumping the charge from the battery. MB have fitted a new battery and done some messing about, but it has not solved the problem thus far. It seems to me like an ECU or similar is coming on when the car is switched off, as it does no happen every the time.
Anyone got any ideas or experenced anything similar?
Dan,
Such faults can be very irritable to solve. Ideally, it requires an ammeter connection to monitor the amphere draw. Is the power dumped over night? In which case, I personally would look into the alternator dis-charge.
If the power dump is over two or three days, then the area to look at is the door switches, interior lights, alarm system, which is partly radio signalled and infra red controlled. Other areas could be glove box light but, I think these only come on with the side light switched on.
ECU's can draw power too, all these need to be looked into and is a process of elimination. Ohhh, do not forget the clock, these have been known for heavy draw.
Goodluck,
Regards,
Yup... decent auto electrican should sort it.
Take Multimeter set with 10A current reading - you may have to lower the setting as you are looking for 0.030A. Remove one terminal from battery and then just touch the terminal back to the battery. Now bridge multimeter/ammeter between battery terminal and wiring loom connection...now place multimeter connections onto wiring loom and battery connection.. finally remove the connection from the battery so that the multimeter connects the battery to the wiring loom. The reason for the jiggery pokery with the multimeter is that when you first connect the battery it pulls a lot (decent spark!).. so that by doing the make connection then connect multimeter and remove terminal.. you take the shock off the multimeter and hence do not kill it.. if you don't well there is normally an internal 10A fuse inside the meter. :wink:
Anyway dark current (ie everything off in car) should be 0.010-0.030 Amps.. this may take 2-3 mins to settle on a modern car as the alarms/lights etc go through initiation/sleep modes.
If you have more current than that then pull all the fuses you can find on the car. Then reinsert one by one until you find your major current drain.. then find out what that circuit does.
As said .. an auto electrican should be able to do this without asking in their sleep.. MB dealers.. useful not!
Any "non standard" add-ons ...immobiliser.sat nav.music etc...one way to trace the problem is to open the fuse panel ..sit inside with everything shut down... set the alarm (if there is no motion sensor) remove fuses one at a time and insert again so the blades of the fuse just touch the fuse socket ..any electrical flow and you will get a spark as the fuse touches..look at the fuse chart and you will see what services are linked to the fuse concerned which narrows down the possible point of leakage you then have to isolate each service in turn until you get no spark.then you have to find out why there is an electrical leak...MB will charge GBP 95+vat per hour for this research and it could take eight hours ...or more and will not be resolved unless each circuit is checked..
Check the electric ventilation fan control unit. These can fail and cause the fan to turn on intermittently when the ignition is off and the current draw is about 12A which can quickly cause a flat battery.
Arnie
Sorry for asking, but would this apply to a 2001 G500?
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Thanks. I have left it with them. I have a feeling that they get someone in to do it.
Any punt on what it could be? As it does not happen all the time it seems to me that it must be something that switches itself on when it should not.