Boot light

[Moody Colbalt Blue]

Hi, Im having problems with my boot light which wont work. If I fit the festoon bulb nothing happens, except the boot open switch stays on in the centre console, even with the boot shut.
I did have problems with the passenger side switch on the front door, I replaced the faulty switch and since then the rear interior light wont work either, but it was working before I fitted the new switch. Finding it frustrating to be honest and not sure if they are related problems or some problem the previous owner had. I've only had the car for 4 months and slowly bringing it back to its glory
Its a 1999 v reg W202 1.8 petrol saloon

 

[mioba]

Isnt is the rear boot switch?

 

[Moody Colbalt Blue]

Ive re set the switch by pulling it out, but no difference

 

[sonic]

Meter the 2 contacts, check there is 12v on the one side switched on. Then check the ground side to the body with a resistance meter.
I would suspect a bad earth.

 

[Moody Colbalt Blue]

Meter the 2 contacts, check there is 12v on the one side switched on. Then check the ground side to the body with a resistance meter.
I would suspect a bad earth.

Don't suppose you would know where the earth is located would you, had all the trim off and couldn't find anything

 

[sonic]

Don't suppose you would know where the earth is located would you, had all the trim off and couldn't find anything

Put one probe of the resistance meter on the earth side of the lamp contact, & the other to a unpainted metal part of the body.
You are checking the cable from the lamp to earth.