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#178: 10-04-2008, 09:39 AM
dschultz's Avatar
Title: Contributor
Location: Capital City, Canada
Car: '05 OBP OBXT 5MT Stg2
Posts: 406
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After picking up my new 'used' MY05 OBXT as few weeks ago, the first thing I noticed was the interior lighting in the front of the cockpit was terrible. I'm so glad I found this mod, I completed it this week. I'd like to share my findings which I suspect is just a recap of some of the comments in this lengthly thread.

My first observation was that my map light module was wired opposite of that indicated in the wiring diagram C/L-02 (page WI-154) from the vacation pix document. The diagram shows +12VDC to the lamps when in reality it was going to the switches first (like the vanity mirror light connections). So rather than cut wires I just flipped pins 1 & 2 in connector R56. You'll need to release the plastic tab by inserting a very thin and narrow blade in from the wire end. Be careful not to short the two wires or you'll blow the fuse and possibly melt the pins, best to remove the fuse first but I couldn't figure out which one it was. M/B fuse #8 powered off the room light but not the map light, so the diagram is still incorrect.

I went a little further with my mod and connected it so that the Room Light Switch could be used to turn off the map lights in addition to the room light. This means I tapped onto the switch rather than into the brown wire to the BIU. This requires a third soldered connection but that's easy to do once you remove the room light module and do it on the bench. Since you have to solder in two diodes anyway this was no big deal. To ensure you DON'T melt the switches use a low wattage soldering iron (25 watt or less) and solder directly to the switch pins not the flat metal bars. Tin all the soldered points first before connecting each wire/diode.

The diodes connect with the anode between the map light bulb and switch while the cathode (stripped end of diode) connects to the room light wire. This is because the BIU activates the lamps by grounding the brown wire and then slowing letting it rise back up to +12VDC. So be careful with the wire connecting the two light modules together as a connection at either end will have +12VDC on it and you don't want to let it touch any ground.

I also used butt connectors so I could remove either light module and not have to unsolder or cut any wires in the future.

Here's a modified wiring diagram:

And two shots of the light modules (map then room).

I hope this info is helpful to anyone contemplating completing this mod.

Last edited by dschultz; 09-06-2014 at 08:13 AM.. Reason: spelling
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