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Lights doing their own thing??

Posted: 16 Apr 2015, 17:10
by Wolfy
My camper failed it's MOT today on an issue with the lighting that I just can't work out, I've checked all the bulbs and the earthing and connections but no joy.

Side lights are fine ( small little bulb in the light fitting).
Driving lights (dipped beam) are fine.
It's when I put the fog lights (main beam) on there's a problem.

When I put the fog lights on the driving light bulb on the RHS goes out completely, the side light which is a separate bulb stays on however.

If any one can point me in the right direction is be very great full.


Many thanks in advance.

Re: Lights doing their own thing??

Posted: 17 Apr 2015, 20:03
by MidLifeCrisis
Can you elaborate on type of lights (square/round), number of lights, year??

Re: Lights doing their own thing??

Posted: 17 Apr 2015, 20:06
by silverbullet
Bad earths. All current taking easiest route to ground.

Re: Lights doing their own thing??

Posted: 17 Apr 2015, 20:56
by Wolfy
Hi there.

It's a "C" reg so I think that's roughly an 84 and has round lights.

Cheers.

Re: Lights doing their own thing??

Posted: 17 Apr 2015, 21:56
by SamsBus2012
Wolfy wrote:My camper failed it's MOT today on an issue with the lighting that I just can't work out, I've checked all the bulbs and the earthing and connections but no joy.

Side lights are fine ( small little bulb in the light fitting).
Driving lights (dipped beam) are fine.
It's when I put the fog lights (main beam) on there's a problem.

When I put the fog lights on the driving light bulb on the RHS goes out completely, the side light which is a separate bulb stays on however.

If any one can point me in the right direction is be very great full.


Many thanks in advance.
I'm a little confused here, are you switching the fog light on (the red one on the back switched on with the separate switch on the dash) or are you putting the main beams on (puling the indicator stalk toward you) and getting the blue tell tale light on the dash.. If its the latter, the main beam is on a different circuit to the dip beam so when you switch it on the dip part of the bulb is disconnected. So in your case it's either a bad connection as Silverbullet says on the rhs lamp only or a dodgy bulb. Swap the bulbs over and see if it makes a difference. The three pin connector on the bulb can corrode too (and cables break down with age) - you can get replacement connectors easily which you can splice in. Clean your earth crowns under the dash.

Re: Lights doing their own thing??

Posted: 20 Apr 2015, 21:15
by Wolfy
Success !!!

I'd checked and double checked all my earths, I'd checked bulbs, bulb holders and all connections. Once I started comparing the two headlights to see which wire was powering which element of the bulb it occurred to me that the bulbs had different power supplies. Tracing the wires to the fuses it turns out I was missing a fuse. No surprise but once I'd fitted a fuse it all worked fine, who'd of guessed.
Another learning curve I guess.

Anyway, thanks for all of those that offered help and advice.

Best regards.

Re: Lights doing their own thing??

Posted: 21 Apr 2015, 18:47
by CovKid
fuses are the first thing to check.

Re: Lights doing their own thing??

Posted: 21 Apr 2015, 21:03
by Wolfy
I know they should be but I didn't realise that both front fog lights ran off separate fuses, and with one of them coming on but not the other I ruled the fuses out ( not something I'll do again).

It's all a learning point and I don't mind mistakes that in the end educate me in one way or another.

Cheers again.