 | Home > Maintenance & Modifications > Puma: burnt headlamp relay |
 
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610   
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Root cause....
http://www.defender2.net/forum/topic13683....amp+switch http://www.defender2.net/forum/topic13748....amp+switch http://www.defender2.net/forum/topic13958....amp+switch If you go through life with your head in the sand....all people will see is an ar5e!! Treat every day as if it is your last....one day you will be right!! Last edited by K9F on 23rd Jul 2012 3:49pm. Edited 1 time in total |
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23rd Jul 2012 11:08am |
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| Molusk Member Since: 20 Dec 2011 Location: Loire Valley Posts: 43  
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The switch seems to be OK, as it does its job. |
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23rd Jul 2012 12:55pm |
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| Molusk Member Since: 20 Dec 2011 Location: Loire Valley Posts: 43
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Moreover, as there is a relay, I guess the current through the switch should be very low, shouldn't it?
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23rd Jul 2012 1:14pm |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610
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Did you read the links I posted? 
Taken from the third link....The current should be low but it obviously isn't...
As documented it IS a common fault. Dismantle the switch and have a look at the detailed contact, or just ignore it until the switch fails, probably at the most inconvenient time!... If you go through life with your head in the sand....all people will see is an ar5e!!
Treat every day as if it is your last....one day you will be right!! |
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23rd Jul 2012 1:46pm |
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| Molusk Member Since: 20 Dec 2011 Location: Loire Valley Posts: 43
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I did read your links, but how a faulty switch makes a relay burn? And why when replacing the relay everything is back in order? |
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23rd Jul 2012 2:18pm |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610
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Is this a wind up? I am just trying to help and have given you the information you need.....
Basic electrics from a basic (well maybe not so basic) electrician..... 
If the resistance of the switch is reduced through burning/shorting out the current in the circuit will increase and exceed circuit limitations. This may take some time in the case of a relay drawing more current than it should before it eventually burns out. Replacing a burnt out relay without finding the cause is just a 'sticking plaster' fix as that relay may possibly also burn out. Voltage=Current X Resistance. Therefore... Current = Voltage divided by Resistance And Resistance = Voltage divided by Current. Also Power (watts) = Voltage x Current. Just check the friggin' switch it'll not take long and if there's nowt wrong forget it. If not we could theorise and surmise for ever what may or may not be wrong....Please! If you go through life with your head in the sand....all people will see is an ar5e!! Treat every day as if it is your last....one day you will be right!! |
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23rd Jul 2012 3:56pm |
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| ZeDefender Member Since: 15 Sep 2011 Location: Munich Posts: 4731  
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Wine time... Tell someone you love them today because life is short.
But shout it at them in German because life is also terrifying and confusing... |
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23rd Jul 2012 5:11pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8580
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Yes the main switch does burn out as I well know.
However since the relay base is discolouring suggesting heat build up there, could it be bad contacts within the relay holder? I would be tempted to check the light switch, to replace the relay holder and check, clean and tighten the terminals/contacts on the relay holder. Poor contacts can causing sparking etc and increase heat. Those comments are from a non sparky. Brendan |
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23rd Jul 2012 5:40pm |
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| Molusk Member Since: 20 Dec 2011 Location: Loire Valley Posts: 43
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Firstly, thanks to all of you to try to help me to solve this burning relay issue.
I checked the main switch, and the dipswitch. Both of them seem in perfect working order (no burning, no melting). I took some pictures of the relay, and the relay holder, to show you:  Click image to enlarge Click image to enlarge We clearly see there was an overheat in the holder area, but no short circuit as the blue wires are discoloured only close to the terminals. So the question is: terminals/holder faulty, or the relay itself? According to the fact the relay has been changed less than 1 year ago for the same reason, I guess the root cause is elsewhere. Moreover, here are some pictures of the relay: Click image to enlarge Click image to enlarge I see no burning, no melting, nothing. So it seems that the trouble comes from the holder and its terminals, no? It was my first idea, but I do not see any spark when lights are on. And assuming one terminal is not properly crimped, OK for an overheating zone around these terminal. But how comes I have overheat marks on 2 terminals? And the wires seem to be correctly crimped behind these terminals... 
PS: no need to remind me the Gauss Law  |
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23rd Jul 2012 9:04pm |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610
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I would remove the relay, remove/disconnect the headlights, remove the fuses and carry out an insulation check of all the associated cables between each other and to earth. If you go through life with your head in the sand....all people will see is an ar5e!!
Treat every day as if it is your last....one day you will be right!! |
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23rd Jul 2012 9:15pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17362 
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I have before now seen a similar effect when the female part of the spade terminal has been badly formed, is corroded, or is not tight on the male part, resulting in a high impedance at the connection.
It might be worthwhile extracting the female parts from the plastic holder (the retaining clip can normally be freed with a jewellers' screwdriver) and thoroughly cleaning them, and then checking that they are a snug fit on the male connector. When satisfied, refit into the holder shell. |
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24th Jul 2012 12:31pm |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610
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Excellent point Brendan/Blackwolf. I've witnessed this too with a green 'furred up' deposit!
I would carry out your suggestion prior to insulation testing. As long as you don't insulation test the coil of the relay you could leave the relay connected and test through the contacts. This would also prove/disprove the corrosion/bad fitting theory. Naturally that is if you have access to an insulation tester of course. If you go through life with your head in the sand....all people will see is an ar5e!!
Treat every day as if it is your last....one day you will be right!! |
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24th Jul 2012 12:47pm |
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| Molusk Member Since: 20 Dec 2011 Location: Loire Valley Posts: 43
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What I plan for tonite:
- measuring current through the relay - measuring internal impedance of the relay, when closed of course, and comparing with new one's. I will perform this measurement on the relay terminal directly (with relay on the shelf, but feeded with flying wires from a 12V battery), then from the holder terminals with relay back in place. - with IR T°C sensor, measuring T°Cgradient between relay and relay holder. |
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24th Jul 2012 3:12pm |
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| Moffett Member Since: 08 May 2018 Location: Sligo Posts: 69  
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I have this exact issue, switch appears okay, long time ago I know, but what did you find?
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14th Jan 2022 12:14pm |
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