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Home > Technical > Front fog failure |
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Yorky Bob Member Since: 28 Apr 2015 Location: Yorkshire Posts: 4561 |
Have you taken out one of the fog lights and put power through it ? First basic test IMHO. FL2 MY10 TD4 GS traded in at 2 years
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18th May 2017 8:26 pm |
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somerset simon Member Since: 15 Dec 2014 Location: somerset Posts: 2 |
Hi Bob
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20th May 2017 8:26 am |
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Worms Member Since: 31 Oct 2017 Location: Highlands Posts: 635 |
Old thread, but wondering if the OP managed to find the fault on this?
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21st Dec 2017 7:22 am |
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dorsetfreelander Member Since: 20 Jul 2013 Location: Dorset Posts: 4354 |
Are you actually getting power to the lampholders? If the relay is clicking then it just proves that the internal coil is OK, it might have burnt contacts internally. I would swap the relay then if OK and fuses OK I would suspect a wiring fault downstream. You might have to wip the front off (30 min job) or wheel arch covers to get in .
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21st Dec 2017 11:01 am |
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Worms Member Since: 31 Oct 2017 Location: Highlands Posts: 635 |
Thanks, the photos are really helpful (assuming that the 2011 facelift model retained the same basic wiring layout as my 2010 MY). I’ll try swapping over the relay and also read the voltage at the lamp when I get a chance in daylight (not much of that around at the moment!). Am I correct in thinking there should be 12v continuously at the lamp when the ignition is on and that the relay switches a resistor in/out to control the path of the current? 2005 D3 2.7 Auto
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21st Dec 2017 6:33 pm |
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dorsetfreelander Member Since: 20 Jul 2013 Location: Dorset Posts: 4354 |
No resistors involved, the relay is just a switch that is activated by a current through a coil inside the relay casing. Usually relays draw a small current from the control source and then activate a switch to control a larger current to a load like a motor or a bulb or something. You should see 12v at the bulb holder when the foglamps should be on or nothing if switched off. No inbetweens. 3 x FL1 2 manual + 1 auto
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21st Dec 2017 6:41 pm |
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Worms Member Since: 31 Oct 2017 Location: Highlands Posts: 635 |
Thanks, that makes sense. The reason for my confusion is that my previous car was a Volvo and it had a common fault where there was 12v at the headlight but bulbs not working, which was diagnostic of a relay failure on the CEM. The 12v continuous at the bulb was normal and the relay switched in a short circuit to reduce power consumption during start-up. I was thinking that the FL fogs might be similar and be continuous power, switched out by on/off switch and high/low beam stalk. Logically, of course, one would design it to switch power in rather than off! 2005 D3 2.7 Auto
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21st Dec 2017 7:05 pm |
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dorsetfreelander Member Since: 20 Jul 2013 Location: Dorset Posts: 4354 |
There are two ways of driving the bulb, you either feed it with 12v continuous and switch the earth on and off with the relay or fix the earth and switch the 12v. Either way you should measure what is happening across the actual bulb socket. 3 x FL1 2 manual + 1 auto
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22nd Dec 2017 9:48 am |
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