www.ultimatehandyman.co.uk

Hi,

My car has just failed its MOT because of severely reduced light intensity on both headlamps. The mechanic suggested checking the bulbs were properly fitted (which I have done), and if they are, replacing both headlamp units as the reflective coating is probably worn out.

Since the new units are quite expensive, and it has never had an advisory on headlamp brightness, I'm wondering if there is another possible explanation other than worn out reflectors. Is there anything else I could try?

Thanks

Worn out coating sounds suspicious.

Could be dodgy bulbs, could be a power problem, not getting a high enough voltage.

Since bulbs are super cheap I would try replacing one and then comparing the brightness to the other, could be a simple fix.

Thanks a lot.

Just tried replacing one bulb, but they both still look exactly the same to me.

I'm not too electrically savvy, what sort of a power problem could it be? I'm guessing it probably isnt to do with the connections at the headlights themselves otherwise it would be unlikely that they have both gone dim.

The car had not been driven for a few months, could this have affected anything? (batt. had been recharged with a charger and still holds charge)

It sounds like a drop in voltage to me. Normally caused by a failing battery (low on voltage) or high resistance somewhere.

Are the lights fused independently of each other, they normally are these days. If they are then somewhere in the circuit they share a connection prior to the switch, relay or switch is likely.

I think you need to test the voltage at the headlight bulbs with power on or get an auto electrician in to diagnose for you.

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Thanks

I'm far too tight to pay someone unless its an absolute last resort! I'm off on holiday tomorrow, but I'll check the voltages when I'm back.

Thanks again

cabbages......it is possible that both headlights share a common earth.....or two bad earths.
Worth checking!
Hope you had a good holiday.