SL-Class (R230) 2003 -- 2012: Discussion on the SL500, SL550, SL600

SL/R230: Help me ID wires in dome light area

Old Mar 19, 2025 | 06:42 PM
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From: Ann Arbor, MI
2004 SL600
Help me ID wires in dome light area

Please help me ID some of the wires under the dome light on my 2004 SL600. Reason is I wanted to wire in a dashcam which will only have power when the ignition is on. I have checked the voltage on every pin of every connector and only find constant +12V on one red wire. No others have power when the ignition is on. I will therefore have to feed something up there to power the dashcam. However, as explained/shown below, I have two wires which are not connected to anything.

In picture 1, I am pointing to a 2-pin connector which continues to two loose wires, not connected to anything. Both wires then go up and left into a sleeve and then down the A-pillar. In picture 3, it appears that sleeve was added later as it is held to a bigger harness with electrical tape. I could not determine where it goes under the dash, it seems to go into the front left fuse box area. Does this look aftermarket? Maybe it was added to power a radar detector? (But now won't take even a small load.)





In picture 2, I am pointing to what appears to be a shielded cable. Any idea? Is this a front windshield antenna for the radio? It also goes up and left and then down the left A-pillar. BTW, its not the microphone because that is separate and still has the part number label.




Picture 3 shows what I call the harness, the sleeve which has the two wires which are not connected anywhere and the shielded cable which I wonder is an antenna feed.



Last, there is a yellow connector which seems to go to the "SOS" switch. Since all the telephone stuff has been disconnected, I assume safe to disconnect that. I thought I saw it blink a few times, making me wonder if it is using power.

Thank you for reading and hope someone recognizes these wires.

(More on those non-connected wires. One wire is ground. With ignition on, the other showed 5V, but as soon as I put even a 100mA load on it, the voltage fell to nearly zero.)

Last edited by mrvedit; Mar 19, 2025 at 06:45 PM.
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