Interior lights draining battery

[Jocarl011]

Ok got a strange one here, the interior light circuit is causing a large current drain to my battery on my Tourneo. The thing is, all the lights go out after a few minutes like they should so I have no idea why this could be happening?? I have disconnected the 10a fuse from behind the glove box for now but really need this sorting! Any ideas?


Thanks Carl.

[Jocarl011]

Anyone got any ideas? Struggling with this one!

[the dutch guy]

pull the lights out and measure current at the fuse.

[mnxtrany]

If the - low battery condition - only occurs when the lights are on/ after they have been on - then there's likely to be a short on that circuit. + to - earth.
If the fuse you have removed is for that circuit and the low battery condition does not reoccur then it's likely there is a short in that circuit.
With the circuit isolated from the battery power use a multimeter to check for continuity from one point to another + and - wires and for continuity from + to - earth on each section of the circuit.
Where there is continuity + to - then there could be the problem.
Electronic gizzmos such as the timer for lights out can give misleading indications so make sure such a thing is disconnected from the circuit/or part of you are testing.
On more modern electronic systems the use of a multimeter can knacker the system.
Better to have a circuit diagram to follow, know what you've got.
Better to show information re' your vehicle.

[the dutch guy]

a multimeter cannot "break" a electronic system, especially not a rubust automotive computer.

usually these issues come from crappy connections. most lights are negative switched, so the light always has power and a dodgy wire somewere can leak to ground enough to pull power but not light the bulb.

[mnxtrany]

The Dutch Guy.
a multimeter cannot "break" a electronic system, especially not a rubust automotive computer.

usually these issues come from crappy connections. most lights are negative switched, so the light always has power and a dodgy wire somewere can leak to ground enough to pull power but not light the bulb.

I was informed that the use of a multimeter on modern electronics - signalled - could damage the electronics. It happened to a fella with a van who had taken out and put back in the battery = things didn't work. He used a multimeter and knackered the van electronics.

I havn't done much electrical work on the my 17 yr old van except to add to it. I put the switches on the positive side. Long time ago the power/switch was on the positive - safer - . I apologise if I got things wrong.
Thanks for the info'.
I'll have to have a look sometime.

[the dutch guy]

a DMM (multimeter) is in a electrical sense just a very high value resistor when measureing voltage. it is basically impossible to inflict damage with that, especially not on automotive components. correlation is not causation. 99.99% chance his system was already nackerd before he got the DMM on it. putting in a fully charged fresh battery on a fully drained system however.... ever wonderd why you get sparks when hooking up a battery to a car? yeah, trust me, it was not the DMM that packed the car in.

[mnxtrany]

To the Dutch Guy. Thanks for the info' re neg' switching. Had a look at the wk shp ml a few days ago and could see the neg' side switching on the interior lighting circuit.
The reversing lights weren't working - found the gearbox switch was at fault. That circuit is switched on the positve side.

[ake]

It’s probably your battery that’s knackered