I would like my xB interior cathodes to act just like my dome light. One position tied to the door trigger to light up when the door opens or pulse with the keyless entry, another to turn on without the key in the ignition and an always 'off' posistion.

I pulled the dome light to get a better look and found only two wires for the dome light.
A red/yellow and blue/yellow. So, I’m guessing switch “On” completes circuit with the always on wire and the grounding screw. And “Door” it completes circuit with the door trigger which is a triggered ground. A look the wiring diagram in the tech section here confirms there’s a negative door trigger on top of the fuse panel—I’d tap the trigger ground there for the cathodes.

a) Is there a preferred place to tap an ‘always on’ 12V or just any hotspot on the fuse box?

b) Working with an always on 12V connection makes me want to disconnect the battery in case I touch a live wire to the chassis. Is there a reset code on the stock radio? When I bought the car they couldn’t provide a reset code, they said “Take it back to the dealer and we’ll reset it”. None of the other xB guides mention reset codes; and the manual just says you’ll have to change the equalizer setup back to xB.
Does the stock unit even have a reset code?

c) Any dangers in the set up I’ve described? Especially with the fading circuit of the door trigger. Will cathode inverters work okay with that fade, could the extra load damage the fade circuit?

d) What do need in a switch? A 3 position 3 pole switch? Any specific switch suggestions?


Has anyone done this? I’m primarily concerned about the dimming effect with the keyless entry and overloading whatever gizmo does that trick.

Edit: Subject line for clarity.

 

First, you ask some pretty good questions. I like your idea and I don't think it would be a problem. I would highly recommend running your power through a relay instead of hard wiring it into whatever source you choose. This would alleviate any extra load on the system you are tapping into. This would also elliminate any adverse affects caused by the door fading effect. In terms of a switch, it depeneds upon how you want it to be used. If you want to be able to select what 'effect' you want, (for example, "Today I want my cathodes to come on when I open my door" or "Today I want my cathodes to flash when I use the keyless entry") I would suggest a Single Pole-Triple Throw switch. This would allow you to choose how you want the lights to act. But it would only allow one setting at a time.

If you want the cathodes to work with all of those (keyless entry, hard switch, and door switch) I would tap all three of your power feeds into three seperate relays and have those three relays feed your cathodes, that way, when power is supplied to any one of the three relays, *bingo* your cathodes come on!

Hope this helps.

 

Good suggestion on the relay, thanks. That’ll isolate the circuit.

I haven’t pulled the dash to take a multimeter to the fuse box, but I did look at the behavior of the dome light, it’s got two wires, one hot and one negative somehow tied to the door trigger/keyless entry; and a three position switch Door/On/Off. The on and off are pretty obvious and trivial. The “Door” is always on with the door open and flashes/fades with keyless entry. That’s the bugger I want to know more about, I know it’s a negative/ground.

If anyone has any experience with the door trigger and how it behaves let us know.

As for protection to avoid warranty problems, the relay suggestion is very good and professional. I’ve seen some talk about using a diode to prevent backflow on the door trigger, which couldn’t hurt.

The ‘trigger’ wire I’d like to use and does what I want and is right there on the dome light…but It gets lost in the headliner and I haven’t wanted to pull the headliner until I know more—anyone know where that sucker goes before I chase the wild goose?

 

The resistors are gonna be needed. i spliced a CC into the dome light, on the door open side. It didn't like it. If I turned the switch to on, the dome comes on, but when I switched it to door, the dome fades to a dull orange, barely lit look and the CC would come on. BUT, it wouldn't go off. After a while it would and then it wouldn't come back on unless I turned off the key and closed all the doors and waited a few minutes. Sometimes it wouldn't turn the CC on in either position. I don't think there's enough juice for it. I probably should've used an LED bar instead. I even pulled half the headliner down and ran the wires up to the rear view mirror mount and mounted the inverter underthat lump there...

There's another post about it around here that tells which wire is which. If you get it figured out, please give us the details and more specifics on the right relays would be helpful too.

 

Resistors or relays? ;). Thanks...good info on the powersucking of the CCs fed from the dome light from your 'it goes orange' info.

Something is special about the door trigger wiring, either where to tap it, how it acts.
or what the heck it does to make the dome light 'door' swtich act like it goes--fade, keyless, door open.

Diode comments anyone? From my limited knowledge it sounds like a backflow, something is triggering the door trigger...a diode would stop the backflow..but which way to install, where to install..which diode to use???

Might be awhile before I get serious and pull things, just looking at the waters now.
Pulling the headliner scares me for right now--don't want to fark up my baby's skin with experiments. :D

 

From the tech section on this website:
DOOR TRIGGER red/white - top of fuse box, 9 pin plug
DOME SUPERVISION use door trigger


That’s the key point it’s a negative according to the diagram…does it just pulse with keyless entry. Relays, I can deal with. Isolate it with diodes? Does the red/white just pulse and go into a factory relay with a fader gizmo to get that 10 seconds of light on the stock dome light? Oh, the questions.....

 

cold cathodes are like flourescent lights. they are a "rapid start" light. The fade thing is not going to work with them.

 

i realize this is over 3 years old, but can LEDs be hardwired to the dome lights without using a resistor/relay safely?