Map Lights on with Dome light Mod

[xekon]

@mmarton sounds like a connection you made went bad, what about the backseat dome light, does it still come on, also did you stick with the stock bulbs or use leds?

 

I particularly like the way the connections were done here: https://www.legacygt.com/topic/13352-map-lights-on-with-dome-light-mod/page/8/#comment-1197531

Edited January 19 by xekon

[mmarton]

Thanks.  Yes, both map lights and the backseat dome come on when manually turning them on.  I also replaced the stock bulbs with LED.  I checked and rechecked the connection.

[xekon]

and does at least the backseat dome come on when opening the door?

[mmarton]

Nope.  Car is dark.  The hatch light comes on when I open the hatch.  That's it.

I asked the repair shop to have a look.  They saw the mod and said, "sorry."

[xekon]

I was still in the process of still reading through this massive thread start to finish.... at one point your dome did still come on:

https://www.legacygt.com/topic/13352-map-lights-on-with-dome-light-mod/page/14/#comment-2192303

at that point I would have guessed that maybe your diodes fried and need replacing if the wire connection between the two lights was still good, however if the rear dome light is not working at all that is more troubling and I am not sure, I would probably open all four doors (incase 1-2 of the door switches went bad) then with all 4 doors open take a volt meter and probe the dome light for power, being careful not to short anything together while your checking. (I am uncertain what all activity can fry the BIU, but it seems like they should have fused that thing better from the factory!)

To me it seems like the only things that can go wrong are a bad connection as a result of the mod, or a damaged BIU.

Luckily one guy outlined how to fix the BIU: https://www.legacygt.com/topic/86431-diy-05-blbp-stereoheat-switchesmirror-switch-illumination-repair-biu-repair/

Edited January 19 by xekon

[mmarton]

Thanks.  I'll check for the dome for power and try new diodes.  At this point of ownership, I'm not thrilled about taking out the BIU and doctoring the board.

[xekon]

On 6/5/2014 at 11:02 AM, RustyShackleford said:

It seems to me like the risk could be eliminated by putting a 1 amp or so inline fuse in. If you get it wrong, it'd just blow the fuse.

I am trying to find the ideal place to put a 1 amp fuse, I would like to do this mod soon but putting a fuse on the BIU first would be nice.

[xekon]

On 3/27/2009 at 9:30 AM, RustyShackleford said:

 

Right. A SPDT to connect it up into the two different modes.

I think a circuit with a single PNP transistor will do it though.

I have to brush up on my bipolar devices - been working with

mosfets for too long ...

@RustyShackleford did you end up using the PNP transistor, your solution sounds great to me, I would be occasionally camping out my rig as well.

[xekon]

On 9/6/2014 at 11:09 AM, RustyShackleford said:

Haven't looked at the circuit in awhile, so going from memory ... but, yes, pre-mod the brown wire should be near 0v when the dome light is on, rising to 12v as the lights dims and turns off. BUT, the critical thing is to make sure you do not apply 12v directly to the brown wire; that is the purpose of reversing the wires going to the map lights. Just because the brown wire is at 12v sometimes (when the dome light is off) does NOT mean it is ok to apply 12v DIRECTLY to the brown wire, which is what you'd be doing if you got the wiring at the map light end of the new wire wrong. It's been suggested here, and I think it'd work, to put an inline fuse in the new wire (the one running from dome light to map lights). Maybe an amp or so. If you get things wrong, that fuse will blow, protecting the BIU. Inline fuse-holder is readily and cheaply available at parts store. You could even remove it if everything seems to be fine.

Ah hah, so one good place to put the inline fuse is in the wire that goes between the lights, thank you.