Electrical drain problem

peteslag said:
Have a look at this:

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

In VERY basic terms, your car is using energy when it shouldn't, this is why the battery is draining. Current is energy, voltage is the pressure that pushes the energy down the wires and through the components. To measure this energy you need to put the multimeter into the circuit. This is why you have to disconnect the battery and connect the multimeter in between the the battery and the cars wiring. You don't need to pull each fuse in turn as it says in the wiki guide, just disconnect your sat nav and CD changer in turn and monitor the current levels. When the current drops down to an acceptable level you have found your culprit.

As said previously most modern cars need a bit of time to go fully to sleep, I would leave the car for 30 minutes after disconnecting the battery to let this happen.

If the sat nav or CD changer isn't causing the problem all is not lost, just let me know and I'll walk you through the next stage of fault finding.
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Pete I've connected everything back up and with the multimeter set to DC on Amos there is a current of 0.011/0.012. Is this acceptable or should the reading be 0. Cheers Jay
 
That equates to 11 milliamps, WELL within limits and wouldn't drain a battery overnight. This means you have an intermittent fault, every leckies worst nightmare. At 11 milliamps your car is not in the fault condition and will be near impossible to fault find. I'm guessing that dodgy looking wiring is related to your woes. If it were me, I'd have a good look over the cables and look for damaged insulation or bad connections. Failing that monitor the meter whilst agitating the wiring loom to try and get it into the fault condition. Failing that........find a good auto electrician. If the electrician you used had anything to do with that wiring, I would advise you not to use him again.
 
peteslag said:
That equates to 11 milliamps, WELL within limits and wouldn't drain a battery overnight. This means you have an intermittent fault, every leckies worst nightmare. At 11 milliamps your car is not in the fault condition and will be near impossible to fault find. I'm guessing that dodgy looking wiring is related to your woes. If it were me, I'd have a good look over the cables and look for damaged insulation or bad connections. Failing that monitor the meter whilst agitating the wiring loom to try and get it into the fault condition. Failing that........find a good auto electrician. If the electrician you used had anything to do with that wiring, I would advise you not to use him again.
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Sorry Pete, it's more than that, lead wasn't in the 10 amp slot, Doh. I think I've traced it to the cd changer, problem is the previous owner has somehow wired them together on to the same circuit. Removing the cd changer fuse does nothing. Removing the nav fuse deadens them both. Il have to remove the centre consol and trace the live then disconnect the cd changer. Am I right in thinking that. Jay
 
This is very odd, why would you alter the car's circuitry? Was the CD changer circuit damaged or not working, maybe that is why they piggy backed it onto the sat nav circuit. What cable did the auto electrician repair in your first post?

I've never had to do any electrical work on my Z4 so I'm afraid I can only give you general guidance on fault finding. Plus, it is hard to give advice on something like this if I can't actually see it. Just to warn you, electrical fault finding can really mess with your mind especially if it is a circuit that has been tampered with by a DIY'er. It can lead you down rabbit warren after rabbit warren.
 
I know what you mean, I'm a heating engineer and without being in front of something it's difficult. Auto elec said he repaired a cable behind the seat but I'm suspecting he just plugged the cables back in to the changer as that brings everything on. Il try and download a z4 wiring diagram and strip the centre consol again at the weekend and try and put everything back to standard. Thanks for your help, I feel I'm getting somewhere now. Jay
 
One last thing to help you on your way. Rather than fault find with live voltages, you can use continuity checking with the battery disconnected. There are some systems that can cause you problems if you accidentally short them to earth whilst poking multimeter probes about the car when it is "live". Set your multimeter to ohms, plug the red lead into the ohms socket on the multimeter and black to com. Measure between the suspect live cable to earth. The resistance to earth would be extremely high on a non faulty circuit but I suspect it will be about 24 ohms if you are drawing 0.5 of an amp. Once you have found the suspect wire disconnect it and re-test to earth, if you get a much higher figure you have found your fault.

Good luck :thumbsup:
 
Wanna give a big thanks to Ducklakeview for his help today. Spent all afternoon there tracing an electrical fault that no auto electrician would touch. Seem to have traced the fault to a very badly damaged ground cable. Replaced the cable and checked everything out and all working as should now. Thanks again Mike :thumbsup:
 
jamesditchy said:
Wanna give a big thanks to Ducklakeview for his help today. Spent all afternoon there tracing an electrical fault that no auto electrician would touch. Seem to have traced the fault to a very badly damaged ground cable. Replaced the cable and checked everything out and all working as should now. Thanks again Mike :thumbsup:
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No probs.. Here's hoping it'll be back to itself once you replace that battery..

Mike
 
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