hi all, thanks for reading this. I have a 2014 Sport Venture 1.6. The low-beam headlights (both) have stopped working. bulbs fine (replaced anyway). There is power getting to bulb sockets. But strangely seems power on both sides of bulb, ie, multimeter to ground from both connections of bulb socket to ground shows +12v. Side lights, high beam, all else working 100%. Fuse fine. (i used to be a domestic installer so know my way around a circuit). I am assuming this is going to be a grounding problem. But i can’t find a circuit diagram that shows how and where this grounds (aslo confused why the ground side of the socket would be +12v). The wiring colours to the bulnbs are blue, green+white. I can’t find this on any circuit diagrams online. Any thoughts comments or help much apreciated.
I agree. However all the diagrams I have are USA wiring and the colours vary!
But there is a chance the G2 ground point, behind the internal fuse box is connected to the Low beam leads. If that has been disturbed (most unlikely) or got soaked/rusted by the usual grommet leak, it could be the problem. I think more likely is a break in ground wires from the lights because if G2 is flakey then other things might not work.
G2 is a pain to get to, but possible.
This pic of the G2 is from when I added a power pack for a dash-cam on my 25AE (also 2014).
If that’s not it then the (easier?) alternative is looking up behind the fog lights from underneath at G5 (left) and G6 (right).
Richard,
That is brilliant, and gives me a good point to start from. Another thought came to me today. I did read online (not sure how reliable) that the lights ground through the switch. As i can’t find an accurate circuit diagram, I can’t be sure if this is right or wrong. But if that is true, and the switch is at fault, that would explain why there is power at the bulbs, but no circuit. So I will try your grounding points first, and thanks again, and then try the switch also. And can I just say thank you so much for your time on this. I feel a bit lost in the wilderness trying to track this down! Chris
The vast majority of bulbs on the car body have ground as one of their terminals but not all, eg Interior light. So if both pins have 12V then the controls are OK, the bulb is OK (eg your low beams) but the final hard-wired connection is not.
A lot of the higher currents are passed to the load by a relay contact, and generally the relay is energised by completing a ground connection via a switch near the driver.
Most relays and fuses for external stuff and high power live in the fuse box under the bonnet. Lower power fuses for cabin stuff and user controls usually live in the internal fusebox, but not always.
Most of the wiring is as thin and short as possible (cost and weight saving) so earth leads tend to clump together (fewest bolts for factory to do up) on convenient spots near their devices (bulb, fan, radio, etc). Choice of assignment is usually for minimum disruption between looms for LHD or RHD drive cars, where usually only the dash and seat looms are swapped out.
Have fun! It’s actually quite a logical car once you learn how the designers thought.