When I open either front door the "door open" warning lamp on the instrument cluster lights up but the interior light dont illuminate. The "Door" switch in the interior lamp cluster is pressed in but no lights.
Is there a specific relay that controls these lamps or am I "whistling dixie" (again).?

- (#11815) Devon Dave, 17 Nov 03 14:34

Does the room light come on when selected? Proves bulb is ok. Door switch is working as the dash light circuit comes on.
If bulb ok it is that hunt for the missing link again, I'm afraid.

- (#11816) Clive (Bristol), 18 Nov 03 2:42

Yes Clive, the room light does come on when selected via the switch (so bulb is ok). It doesn't come on when you open either front door.

- (#11817) Devon Dave, 18 Nov 03 16:57

OK, right I'd first check that the switch is switching.
Then it's out with the multimeter and look for the break in the wiring! May be in you multiblock connection area ?
Best of luck

- (#11818) Clive, 19 Nov 03 2:35

There is a diode in the lamp cluster. I suspect it has failed. The switches operated by the doors turn the room light on via the diode. The manual switch on the lamp cluster turns the light on directly, and therefore, you may notice, slightly more brightly.
The diode is there, I presume, so that using the manual switch does not have other effects like showing the door open warning on the dash, or sounding the "lights on" warning.

- (#11898) Dave Mason (Sussex), 19 Nov 03 12:36

good point dave, thanks mate. that seems to be fairly straight forward to replace (i am sure i have a diode in amongst my old video and monitor stock) so long as the colours are the same on the mica, it should be the right type.
fingers crossed.........?

- (#11899) Devon Dave, 19 Nov 03 18:29

Well I go to the foot of our stairs.
You learn something every day. Dave your theory, as ever, sounds spot on. Devon Dave hope this sorts it out for you.

- (#11900) Clive, 20 Nov 03 2:53

I mentioned the diode because the original question asked about a relay - presumably wondering what kept the manual switch from messing up the other systems. However the "missing link" could still be in the wiring to the diode.
This is one area I put in the wiring diagram in the Ace Handbook but I see I also put a diode in series with the manual switch. That seems unnecessary but I vaguely recall there were two diodes in there. If you look inside do let me know! Dismantling instructions are in Ace Archives.
Diode type - anything that will cope with the bulb current. If there are two maybe the other is a spare!

- (#11901) Dave Mason (Sussex), 20 Nov 03 10:50

I looked the other day and as far as I know there is only one diode present and connected.
Weather is a bit manky down 'ere at the moment so will have to wait till a dry spell (I can't work whilst wearing snorkel).
Thanks guys, I shall let you know the end result.

- (#11902) Devon Dave, 20 Nov 03 13:13