Interior light driving me mad!

[Clifford Pope]

The interior light in my 64 Mark I saloon has an intermittant fault which repeated investigations have failed to trace.
<br>The light stopped coming on when a door opened. Quick checks showed that the fault lay up at the light itself, because twiddling the bulb caused the light to come on and function normally. Then after a few days it failed again. This time I carefully cleaned the contacts, the ends of the bulb, re-checked the wiring terminals and connectors, and re-assembled. All was fine for a few days, then it failed again.
<br>When I remove the cover and twiddle the bulb, it instantly comes on, and the problem again appears to be cured. I have tried removing the lamp unit, testing all the contacts and connections, and have tightened the tension on the spring clips. The wiring, so far as I can see it, seems to be in perfect condition.
<br>I even began to wonder whether a bulb can be faulty internally, and sometimes need a joggle for the filament to connect. I replaced the bulb, but it makes no difference.
<br>Every time, whatever I do, it works for a week and then fails. Tapping the light, twiddling the switch, make no difference - I have to get the screwdriver out, remove the cover, touch the bulb, and then it is perfect again.
<br>What on earth can it be ? Has anyone ever encountered this before?
<br>Many thanks,
<br>Cliff Pope
<br>

[Alec]

Hello Cliff,<br>
I have never encountered that problem, but have you looked at the light
unit switch, i.e. the integral one that lets you switch it on with the
doors closed. Could your movement of the bulb be putting sufficient
pressure to give contact? Just a guess.<br>
<br>
Alec<br>

[Alan Chatterton]

These bulbs are made foa glass tube with a metal cup in each end. The metal cup is connected to the filament inside. It sounds to me like your caps are loose (happens on old bulbs!)
Put a new bulb in it, (to check you can use a rear number plate lamp they are the same) and all should be well.
Also, try and bend the clips ina bit to give more spring contact on the bulb ends!
&nbsp;
Rgds
Alan Chatterton
&nbsp;

[Clifford Pope]

Done that - new bulb, and I bent the clips in to get more pressure. I got it working fine yesterday, tried it a number of times opening and shutting the door. Crept up on it an hour later - still working. Tried the door this morning (car unused) and no light.
<br>Thanks for trying, anyway!

[Brian]

Hello Clifford
Has the early MK1 got the switch by the steering column for when the doors are closed? As Alec said, I had a similar problem on my MK2 estate. This has the on / off switch on the interior light and the contacts had become dirty. After a good clean it has been fine. Of course, if your car has the on / off switch by the steering column as late MK1, you will not have the switch on the light unit. Just a thought..
Brian