My offside front sidelight is out: Image Unavailable, Please Login Nearside works fine. Swapped out the bulbs (no difference) and checked the fuses (fine). Checked the terminals (clean) and probed them with my multimeter (both read OK). What's my next move?! Also noticed that the lower bulb of my rear nearside light is out. Could this be related? Image Unavailable, Please Login
This really isn't a definitive test if the bulb (the load) is not connected. It can detect a completely broken connection (infinite ohms), but if you have an unwanted resistance (say, a few thousand ohms) in a bad connection, you will "pass" this test when the bulb (load) isn't connected, but will fail this test when the bulb (load) is present. If you could make this same DC voltage measurement when the bulb is in the socket that would be best. If not, one thing you can try is measuring the resistance from the metal bulb socket (should be ground) to the negative battery terminal (or some other good ground) = doesn't need to be zero Ohms, but shouldn't be more than a few Ohms. Don't think the two bulbs problem are related, but will have a look at the euro Mondial QV wiring diagram.
Does your offside front turn signal work? It shares the ground with the offside front sidelight -- so, if a bad ground connection is the trouble, it shouldn't work either. Unfortunately, a euro Mondial QV has an ECU that independently (I think) runs all these exterior running lights so is just a "black box" on the schematic. Your measuring +12V at the socket without the bulb present is a good sign that the ECU is trying to do the right thing.
Assuming you have 12 volts to the bulb holder, then it has to be the earth return- fit a temporary earth to the bulb holder to see if it works
Check if they light up with the parkinglight switched on, on the middle console. Bottom rear lights and front parking lights also light up when switched on, this way you can identify which circuit is faulty.
Yes, all those lights are passing the electronic check control unit (109f) under passenger footrest LHD model. Left on picture.... Image Unavailable, Please Login Mostly this is a problem of bad ground contact near the lamps itself, but as you have 2 lights not working like now, some other issue. If you cannot find a soltution, best is to brigde those lights with a wire to the other side of the car. With the risk a warning lamp will appear on that other box on the right side of this picture. Guido
Many thanks, all - lots to go on here. Can't get to it until the weekend, though. Will report back then!
Sorted! Tested the fuses, tested the bulbs, tested that I was getting 12 volts to the bulb holder. I was, but the reading was twitchy. So I gave the contacts a careful clean, back to shiny metal. And bingo - both lights now working perfectly (front and rear). Nice, cheap fix. Thanks for all the tips.
