480 interior light and cold starting/running.

Can someone tell me how the interior light is switched when the door is opened? No switch can be found and it won't work.
Also on the 480 es Auto it has started running badly on start up when cold and it won't run well until warmed up. This happened overnight so what could have failed as it was fine before. Is there an automatic choke of some sort?
I'm new to these strange cars and I have to maintain my mothers car hence all these questions.
Also when should cambelts be changed and do the valves clear the pistons if one breaks?
Cheers H

[Dan F]

Hi.
Not sure about the light switch as I haven't seen the layout in the 480. But on the 440 the interior light has a switch on the main body of the light and the doors have a black rubber switch on the pillar where the door catch is. Also the interior light should have a 20 - 30 second delay when you close the doors, so see if that is operating.

The bad running when cold could be the coolant temperature sensor telling the ECU that the coolant is always warm and hence no enrichment at startup. Or it may be a faulty thermostat not opening (or closing) and giving bad readings to the sensor that is just relaying the bad readings to the ECU.

I think that the Haynes manual states that cambelts are due every 48,000 miles with the 4x0 series.
Some seem to think they are only due every 60,000 miles however.
I think the cylinder heads are of interference design and therefore if the cam belt breaks you *will* get some damaged valves and maybe pistons too.

Hope that helps somewhat.

Dan.

I've solved it! The starting problem anyway. The plug under the throttle body which connects to the throttle position switch was the problem. It looked clean and corosion free but I cleaned it with WD and the problem has gone and it starts fine again now. You need to prise out the spring clip around the plug before it will undo.