Interior light delay unit

[daimlerman]

The interior light delay unit on the touring has randomly started to play up this week.

Car was used on Wednesday morning,left standing until going to work Thursday afternoon when it 'failed to commence',giving all the symtoms of a flat battery.Jump started using the gadget kept for the purpose and tucked the gadget into the rear footwell just in case it refused at 2am when I finished work!
Started as normal,of course.
Parked on the drive at home,put 'er indoors Fix It Again Tomorrow away behind it and noted that the interior lights had dropped to about half brightness...
Just been out and had a look and the interior lights are glowing gently,open a rear door and get full brightness dropping back to a gentle glow when the rear door is closed,start the engine and close the front door and they go out as if they were normal,but drop to a gentle glow when leaving the thing.

Any ideas?

[Brianmoooore]

OE interior light delay uses a relay to switch the light, so there should be no possibility of anything other than on or off.
The only way I know of that can make an interior light glow at part brightness, other than a simple poor connection in its power feed,is if the passenger front door pin switch somehow loses its earth and is 'on'. This places the coil of the relay that allows the windows to work with the doors open in series with the light bulb.
Pull fuses to confirm where this glowing bulb is getting power from.

[daimlerman]

Thanks for looking,Brian.
Pulling fuse 27(30A) puts the lights out....
And fuse 21(7.5A)....

Delay unit is a George Graves unit,perhaps five years old and moved home at least twice!

[Brianmoooore]

That's the fuses for the delay module and the light itself.
I've no idea what the internal circuit of this unit is, or how well the design has been developed, but the chances are it uses solid state switching and has become faulty.

[daimlerman]

That's the fuses for the delay module and the light itself.
I've no idea what the internal circuit of this unit is, or how well the design has been developed, but the chances are it uses solid state switching and has become faulty.

Thanks.