Intermittent electrical short - please help finding it!

[Troll Hunter]

_{Hi, All,}

_{I've copied this from my previous thread on fuse box and relays because most people who have read that thread probably won't return to it.}

_{I seem to still have an intermittent short causing me to randomly have a flat battery, which is what the OP was about. In following up with a multi-tester, with the battery removed, I get the following results:}

_{Between positive and negative battery leads Zero resistance}

_{I assume this could be because of the clock and radio memory circuits, but I'm not sure.}

_{Between the following locations and earth:}

_{At the fuses in the fuse box, at all except the four headlamp fuses Zero resistance}

_{The four headlamp fuses Open circuit}

_{At the main starter connection stud, on the solenoid, all leads connected Zero resistance}

_{At the main starter solenoid stud, with all the leads disconnected Open circuit}

_{On the leads that I've disconnected from the starter stud:}

_{Heavy Brown lead Open circuit}

_{2 thinner Brown leads Zero resistance}

_{Red/black lead Open circuit}

_{Heavy Red lead (main connection between battery and starter) Open circuit}

_{Red/white lead connected to other terminal on solenoid (closer to engine block) Open circuit}

_{(Power to operate solenoid)}

_{With the battery positive lead connected and using a test lamp between the negative lead, which is disconnected, and the battery negative post the test lamp illuminates brightly for about 1 second and then fades away completely. If I break the circuit for a couple of seconds and then re-connect the test lamp it repeats the brightness and fading away. I am totally baffled. Is this the result of a capacitor charging up and then being discharged through the test lamp? (I’m showing off my in-depth knowledge of electrickery now. I know how to spell capacitor!)}

_{Any help will be very much appreciated, and many thanks in advance.}

_Mike

[pete3000]

ideally you need a multimeter which can measure amps as a start, if this is only happening with the ign off you could start with any circuits which are powered only when off. i.e clock, radio, alarm, rf receiver. alternator.

By removing a fuse or removing the positive feed to each circuit/item in turn you can trace your current draw. Place the meter onto A range and put the meter in line with the supply to the item powered (not between pos and neg)

i.e with keys out and everything switched off lift main battery red pos lead off and connect the negative meter lead to battery and pos lead to +ve battery lead you just removed. make a note of reading in amps. (positive reading means leads are correct way round, dont worry if reversed)

replace main feed and next go to main fusebox 5/6 fuses? and remove each fuse in turn and put meter leads in place of each fuse blade you are looking for sum of main current.

My betting is on a dodgy rover alarm ecu, they were renowned on the older rover 200/metro with the 2 button fobs for battery drain of 500ma when faulty.

HTH

Pete