need help with wiring for car project

[Kevin Van Sant]

I've posted this to a couple of honda forums but I thought I'd try a
couple of electronics forums too. Thanks for any help.

I undertook my project of adding a map light assembly into the
headliner of my 98 civic LS today. I had to remove all the upper
interior trim to pull down the head liner, but it wasn't too bad. I
mounted the map light assembly and have put everything back together.
I haven't figured out the wiring, maybe someone here can help.

My Civic LS 4D is a '98, the dome light has two wires only. One leads
to the battery + , the other comes from the door switches. (I have the
'98 wiring diagram) The grounding comes from being screwed to the
metal frame of the roof.

The map light is from a 2001 Civic EX 2dr. There are 4 wires (see
picture)


http://img168.imageshack.us/img168/4031/maplightyg5.jpg

From looking at it, I'm thinking black is ground, red is (+), but
there is still blue and green. Green is possibly for the door switch
lead, but what about blue which is tied into yellow (thus tied to
white)?

I have to make four wires become three. I'm either going to have to
tie two or leave one out. Anyone have any clearer idea of this than I
do?

As a follow-up, I decided that blue and red were both (+) so tied
them together to the (+) lead. Black was ground, green was door
switches. I wired it up this way and the map lights work, the
original dome works, but the new dome blows the fuse when I turn it
on. The new dome is what's related to the blue wire (if you look at
the picture it should be clear) So evidently I can't just tie it to
the red, although if I exclude it there is no (+) lead to the new dome
light.
Can anyone figure out how I might wire this differently? Thanks.

 

[mc]

Only a Honda wiring diagram will tell you.

 

[ehsjr]

I've posted this to a couple of honda forums but I thought I'd try a
couple of electronics forums too. Thanks for any help.







As a follow-up, I decided that blue and red were both (+) so tied
them together to the (+) lead. Black was ground, green was door
switches. I wired it up this way and the map lights work, the
original dome works, but the new dome blows the fuse when I turn it
on. The new dome is what's related to the blue wire (if you look at
the picture it should be clear) So evidently I can't just tie it to
the red, although if I exclude it there is no (+) lead to the new dome
light.
Can anyone figure out how I might wire this differently? Thanks.

I suspect the blue wire needs to tie to the other yellow
wire in the picture, or to switched ground at the end
of the blue wire not shown in the picture.

Here's why:
Some cars (all cars?) are wired so the the door switches
are grounded when the door is open. I suspect yours is
wired that way. What that means, if it is true, is that
when you are in the car with the doors closed and you
use the dome light switch, the switch grounds the light.

From the look of the switch, I'm guessing that the switch
connects the black (presumably ground) wire to the yellow
wire (that is tied to the blue wire) when you turn the
dome light on.

It looks like the red wire (+) goes to the spot lite on the
left of the picture and connects to the white wire at the spot.
The white wire goes across to the spot lite on the right side,
where it is joined to a yellow wire that goes to the dome
light. Therefore, the dome light is connected to (+).
That means that the other yellow wire to the dome light *must*
get connected to ground by the switch to turn the light on.
That yellow is the one that is currently tied to the blue.
If you tied blue to (+) and then turn on the switch, it has
to blow the fuse.

That leaves the question of where did you connect the blue
wire to (+) ?

Ed

 

[Kevin Van Sant]

I suspect the blue wire needs to tie to the other yellow
wire in the picture, or to switched ground at the end
of the blue wire not shown in the picture.

Here's why:
Some cars (all cars?) are wired so the the door switches
are grounded when the door is open. I suspect yours is
wired that way. What that means, if it is true, is that
when you are in the car with the doors closed and you
use the dome light switch, the switch grounds the light.

From the look of the switch, I'm guessing that the switch
connects the black (presumably ground) wire to the yellow
wire (that is tied to the blue wire) when you turn the
dome light on.

It looks like the red wire (+) goes to the spot lite on the
left of the picture and connects to the white wire at the spot.
The white wire goes across to the spot lite on the right side,
where it is joined to a yellow wire that goes to the dome
light. Therefore, the dome light is connected to (+).
That means that the other yellow wire to the dome light *must*
get connected to ground by the switch to turn the light on.
That yellow is the one that is currently tied to the blue.
If you tied blue to (+) and then turn on the switch, it has
to blow the fuse.

Thanks, I think I finally have a clear picture of what's going on. I
did in fact get it working a short while ago simply by dead-ending the
blue wire. I appreciate your detailed response.

That leaves the question of where did you connect the blue
wire to (+) ?

I had earlier tied it to the red wire (+) to the same (+) lead which
fed the existing dome light. Your description explains why that
failed.