Hi

I have a 2001 Daimler Super V8 with the individual reclining rear seats and the seat switchpack in the console between the seats. None of those switches is illuminated. At first I thought they weren't illuminated by design but I've noticed that in the wiring diagrams each switch contains a bulb symbol. All the switches work perfectly otherwise.

I've had to change switch bulbs in the sport and cruise control buttons behind the J-gate so I know they fail but for all of them to have failed seems a little coincidental. I have three questions, then:

1. Should I expect them to be illuminated?
   
2. Is there a single item that could cause all of them to be out? At first I assumed a fuse but I can't see one identified and that would be a little counter-intuitive anyway because I can't see the switch illumination being on a seperate fuse to the switch itself.
   
3. Can you replace the bulbs in these switches in the same way that you can change them on the other buttons? If so, I'll probably change them. If not, I'll leave them - it's hardly a hardship having to turn a rear light on to see them.

Thanks

Mark

 

Perhaps they only illuminate when the headlights are on?
I'm not sure if they should illuminate or not.

 

It would make sense to engineer them such that you could see the switches
in the dark. So a quick look see at night could give you a pleasant surprise.
Short of that, if there is power at the switch and the light is not illuminated,
(with the headlights on) then you probably need to replace the bulbs.

 

They're not illuminated when the headlights are on and all the other switches in the the cabin are illuminated and each of the switches in the wiring diagram show lighbulbs plus "state" leds in the seat heater switches to show they are switched on. The state LEDs work fine.

I'll pull one switch and see what I can find and whether I think I can easily replace the bulb. I'll update this thread once I've done that.

 

I presume that you have looked at Fig. 12.7 of the Electrical Guide. I see that all bulbs for the rear seat switches are connected in parallel. The ground wire (black) for all of them goes through a pair of pins (in a connector) marked as BS4-3 and goes to a grounding point. The positive supply to all bulbs comes through one red wire from a pair of connector pins BS4-18. It is possible that the current through one of these two wires (red or black) is interrupted somewhere, could be in the connector "BS4", causing all bulbs to be out. I would check the wiring and connectors behind the console first.

 

I bought some tiny blue bulbs a while ago and changed all the bulbs in the window switches. You have to carefully pry the switch rocker off and you will see a tiny circuit board with the connector wires sticking through in the lower half of the switch plastic. Remove the rubber piece and poke the new bulbs in similar to the originals. Perhaps the seat switches use the same bulb? I had about 50 of these once but after five 308's, I'm down to these four.

 

That's great guidance and shame on me for not following through and comparing the connections for each of the lamps. In the absence of a fuse for the circuit, a broken or dislodged wire is the natural conclusion. I've got to pull out the centre console to do some other stuff so I'll do that troubleshooting when it's apart. I'll report back.

Thanks for tracing those connections. Lesson learned for me.

Mark

 

Thanks David, I've has to replace a few of these in other switches so I'm ready to do it if I have to. It just seemed a bit of a coincidence to me that they were all gone and @M. Stojanovic has pointed me in the right direction to try that first. If I remember the bulbs are T1 B-Pin 60w - I've got a few in my draw but not enough to replace the bulbs in all 8 switches

Cheers

Mark