Headlight not working + Resolution

[ovalking]

My 1988 A100 O/S dipped beam headlight stopped working (thanks auto-check system).

Fuse test ok. Bulb test ok. N/S working ok, so ruled out switch. Volts at the bulb plug, but bulb won't light.

I guessed this was due to a high resistance joint rather than complete failure. Eventually tracked it down to the fuse box (socket 10).
When the fuse is in place, it limits testing because you can't access each socket independently. So I used the individual blades from a broken fuse in the socket as electrical measurement access points. Resistances to earth were a bit inconsistent. Then I replaced the fuse blades with spade connectors (slightly fatter), and got solid low resistances to earth.

Resolution? I put some solder on the blades of the fuse to make them fatter. Headlight now working!

[Hanuman]

Most fuse boxes have been largely untouched for years. As a result, contact contamination is a problem, especially as the contacts lose some of their natural tension. They’re in quite inhospitable environments.
As an engineer, long ago, many intermittent system problems that I dealt with were resolved by reseating components, whether it be a relay or a processor board.
I’ve resolved a few fuse box lazy contacts by flexing the contact back into a positive position. There’s usually just enough room for a very small screwdriver to fit down the sides. (Which is where the contact extraction tool would go*)


* cue many an autoelectrician- What?