Dome Light Assembly Replacement - Spotlights Not Working

S

StudioWizard

Member
 Los Angeles, CA, USA
I recently bought an OEM overhead light/spotlight unit for my 2005 2.5i to replace the original dome light which doesn't have the two spotlights. It all fits perfectly and looks great, BUT the two spotlights don't turn on. It looks like maybe the wiring harness for the 2.5i isn't set up to provide power to those spotlights.

Does anyone know how to do that or have a diagram for how to get power to those spotlights?

Thanks!
 
Looks like I'm missing one wire. I would think the wires would already exist and be available...

Any suggestions for how to fix this? Can I simply tap/splice a wire and connect it as shown?
 
If I remember correctly there is a difference from Preface and facelift .Preface won’t work in a Face lift.
 
Preface is the early cars 2003/2004.

Facelift is later from somewhere in 2005 to 2008
Preface have the round Tailights.
What year is your car
 
BumpyZ4 said:
Wiring.jpg
Click to expand...

Thanks for sending the wiring diagram. I'm working on deciphering it.... haha Obviously this is the wiring diagram for a 3.0i and mine is a 2.5i, yet all the parts lists I've seen state that the 3-light unit is compatible.

Spoiler question: Does this diagram indicate to you that I could indeed make this wiring work in my 2.5i?
 
Umfaan said:
Preface is the early cars 2003/2004.

Facelift is later from somewhere in 2005 to 2008
Preface have the round Tailights.
What year is your car
Click to expand...

Mine is 2005, but it has round tail lights....
 
StudioWizard said:
BumpyZ4 said:
Wiring.jpg
Click to expand...

Thanks for sending the wiring diagram. I'm working on deciphering it.... haha Obviously this is the wiring diagram for a 3.0i and mine is a 2.5i, yet all the parts lists I've seen state that the 3-light unit is compatible.

Spoiler question: Does this diagram indicate to you that I could indeed make this wiring work in my 2.5i?
Click to expand...
The wiring diagram for the 2.5 is the same. After early 2004 cars were not wired for all options. You are only missing the Red/Yellow power wire. You could run a new wire from the GM5 to the light (difficult) or make a jumper from another always hot power source. The Red/Blue and Brown/Yellow should have power all the time but you need to put a meter on them to verify.
 

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If I make a jumper from one of those always-on wires you mentioned, will the brightness of the lights be lower? (I'm not an electronics expert.) The old dome light didn't have map spotlights, but had two bulbs and apparently two power wires - one for each bulb. And the 3-light unit has 3 power wires - one for each bulb, I presume. So, which one should I jump?
 
The brightness will be the same as they are not high wattage bulbs and even less if you have LEDs installed. I suppose you could jumper the traces but that is much easier to screw up then jumping a wire.
 
BumpyZ4 said:
The Red/Blue and Brown/Yellow should have power all the time but you need to put a meter on them to verify.
Click to expand...

Before the OP does something drastic, this is wrong on several levels. The Red/Blue line only has power when the inside light is on - not much use as a feed for the map lights. The Brown/Yellow is a signal level wire - hanging bulbs off this will probably damage the GM5 module.
 
smorris_12 said:
BumpyZ4 said:
The Red/Blue and Brown/Yellow should have power all the time but you need to put a meter on them to verify.
Click to expand...

Before the OP does something drastic, this is wrong on several levels. The Red/Blue line only has power when the inside light is on - not much use as a feed for the map lights. The Brown/Yellow is a signal level wire - hanging bulbs off this will probably damage the GM5 module.
Click to expand...

Thank you for stopping me. I started to get a gut feeling I might damage something by simply jumping wires. I realize too that there aren't any constant always-on wires in my older harness... My unit only has the cabin light and it turns on under various situations - opening the door, etc - and also dims... If I jumped that circuit, I can see how I'd damage the GM5 unit and/or the LCM.

So, it sounds like I either need to give up and live with the original dome light only unit or do one of the following options:
- Run a wire from the fuse block all the way up to the light unit (if that's even possible) and connect it to pin 8 on the connector
- Create a 12v DC battery pack and stick it in the area of the light unit (half joking here... haha)

Any suggestions?
 
smorris_12 said:
BumpyZ4 said:
The Red/Blue and Brown/Yellow should have power all the time but you need to put a meter on them to verify.
Click to expand...

Before the OP does something drastic, this is wrong on several levels. The Red/Blue line only has power when the inside light is on - not much use as a feed for the map lights. The Brown/Yellow is a signal level wire - hanging bulbs off this will probably damage the GM5 module.
Click to expand...
That's why I said to put a meter on them to verify.
 
That's not going to help. You'll find the switch line floats to v+ but, being a signal line, it won't be able to supply any appreciable current with the caveat that it may blow the control line transistor in the GM5 if a bulb is attached to it

The other line is obviously only powered when the inside light is on, so no use for a map light.
 
I simply fitted LEDs in the original light. You don't get spots but they are a huge improvement.
 
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