Interior lights

[eastkent]

Can anyone help me with how the rear interior light in my 1994 crew cab van works? There's a momentary switch to the left of the steering wheel that lights the ceiling light in the back of the van but I can't work out how to make it stay on, but it sometimes stays on all on its own.

I don't use the light much but when I do it seems to do whatever it wants - if I've been faffing with it it sometimes comes on with the front interior light when I turn the ignition off and open a door, and yesterday evening a neighbour told me it was on when it was all locked up! I went out and pressed the button and it's stayed off since because I've left it alone.

It would be good to know how it actually works because it's been converted to a day van and a working ceiling light would be useful now it's dark in the evenings.

[Altransit]

The switch on the dash is a latching push switch which is no longer latching properly, so sometimes it works, and sometimes it doesn't.

The one in my Mk4 minibus went the same way, and I had to hold the switch in manually whilst the passengers got in (or out)
You really need a new switch, if you can find one for this model, or use an alternative toggle or rocker switch, and fit it somewhere else on the dash

[eastkent]

Is it?? Well that makes sense! I'll have it out and get the multi-meter on it. That didn't even cross my mind because I thought it might be momentary unless some other condition was met, like the other light was on too.

Many thanks!

[eastkent]

A vaguely interesting development: the switch does actually latch as it should but the interior light still goes off when I release the button. Most odd. It must be dependent on some other factor so I will study the circuit in the Haynes book of lies.