PeterCT

New Member
Hi
I recently replaced the main light switch on my '98 Defender 90 TDI and I have now been told that it is burnt out again and the auto-electrician is fitting a relay to resolve the problem. It only has the standard electrical equipment so it seems surprising that this is necessary. Has anyone else had similar experience?
 
I'd be surprised if anyone has not had this experience. Having said that, you should have got a few years out of the last one.
 
Hi
I recently replaced the main light switch on my '98 Defender 90 TDI and I have now been told that it is burnt out again and the auto-electrician is fitting a relay to resolve the problem. It only has the standard electrical equipment so it seems surprising that this is necessary. Has anyone else had similar experience?

This is not the way to proceed in my opinion and the Auto Electrician should know that - this is like flooring over dry-rot.

Either, you bought a Britpart switch and it burnt out because it was rubbish, or there is a fault with the lighting circuits.

I would want to know what exactly is burning out (i.e. which terminals) then test that circuit to see if there is a fault, bad connections can cause higher resistance and power will be dissipated as heat, this can burn out switches, it could be as simple as bad connections. First I'd get the fuse out the fuse-board and measure actual current readings for the current draw on the lighting circuits then do some maths to work out if they add up and fall within expected range, if not you have a current draw somewhere driving up the current killing the switch - as LR used Left and Right circuits it is possible someone inept at wiring has made a mistake in wiring or fixing things and connected everything to the LH or RH circuit and put a bigger fuse in to cope, then weak things like the switch die first.

Another thing could be a bad leakage through other electrical equipment, i.e. your light switch may also be energising a window demister or back-feeding power to some other highish power load. Adding the relay will certainly remove current from the switch but it may be covering up a bigger issue.
 
Agreed, what switch was it, High/Low or Off/Side/Full? Those switches are more than able to handle the lighting circuits. Are all your lamps standard? Any spots?
 
This is not the way to proceed in my opinion and the Auto Electrician should know that - this is like flooring over dry-rot.

Either, you bought a Britpart switch and it burnt out because it was rubbish, or there is a fault with the lighting circuits.

I would want to know what exactly is burning out (i.e. which terminals) then test that circuit to see if there is a fault, bad connections can cause higher resistance and power will be dissipated as heat, this can burn out switches, it could be as simple as bad connections. First I'd get the fuse out the fuse-board and measure actual current readings for the current draw on the lighting circuits then do some maths to work out if they add up and fall within expected range, if not you have a current draw somewhere driving up the current killing the switch - as LR used Left and Right circuits it is possible someone inept at wiring has made a mistake in wiring or fixing things and connected everything to the LH or RH circuit and put a bigger fuse in to cope, then weak things like the switch die first.

Another thing could be a bad leakage through other electrical equipment, i.e. your light switch may also be energising a window demister or back-feeding power to some other highish power load. Adding the relay will certainly remove current from the switch but it may be covering up a bigger issue.
Thanks for your comprehensive response. It certainly gives me a few things to think about. The electrician has already fixed it but I will check the amount of current coming through the fuses.
 
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