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Discussion Starter #1
These damn modern cars! I'm working on a project and need to tap the reverse light circuit going to the tail light. 2019 S60 so the tail light circuits should be direct wired to the CEM not LIN controlled like the 2020 and newer.

I tried removing the tail light to probe and test but removing the tail was a bit more involved, so I bought a subscription to VIDA. Now I have the wiring diagrams so I don't need to remove the tail light I can find the wire and tap it, great!

Except the wiring diagrams in VIDA make my brain hurt they don't break out the functions of the wires. So for a tail light you see the 5 wires running from the CEM to the light, and 3 are marked as LED and 1 is an incandescent bulb. No where does it say which function is which like "running lamp" "brake lamp" etc. I can right click and see the signal information, either PWM or 12V and a signal ID like "S1319D" but nowhere I can find does it tell me which wire is which function or what that signal ID corresponds to. If I try to go through "fault tracing" for the reverse light I see the diagnostic sequences and there is further information but I can't tell if I am missing something to be able to diagnose because I am not connected to the car, still not sure I would get the specific info even if I went down that road.

I've probed a couple of the suspected wires but not gotten expected result. I probed the only wire for incandescent bulb shown in the diagram (design info says the reverse light is a bulb) and it had no voltage even in reverse with the lamp lit. I ran out of time, I'll have to go back and tap each of the wires again to test but I thought maybe somebody could help me along if you know VIDA better than I do, probably a long shot but worth an ask...

To the rest of you lord help ya trying to mess with these new cars!
 

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Hi Power6- I definitely can’t offer much help with the wiring diagram, but I’m wondering if the wire for the incandescent is only used in certain markets? I’ve noticed the reverse lights on my S60 appear to be LED.


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Hi Power6- I definitely can’t offer much help with the wiring diagram, but I’m wondering if the wire for the incandescent is only used in certain markets? I’ve noticed the reverse lights on my S60 appear to be LED.
I hear you man, I am soooo doubtful that those reverse lights are a bulb! That is what the service manual says though, you access all info by your VIN so it's supposed to be specific to your car. The wire that supposedly goes to the incandescent bulb measures 5V when the car is on though. I only have a dumb voltmeter I can't measure PWM signals. The manual is very specific that 2019 doesn't have the LIN taillights which would be data controlled (and impossible to tap into the reverse light circuit) but I am beginning to wonder...
 

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I believe the reverse light is the only replaceable bulb in the taillight. I don't have the diagram in front of me, but that should be the wire.
 

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Thanks Tech! It doesn't answer my question totally, not that it's on you to do that ;-) But knowing it's the only incandescent bulb in there (it really looks like an LED externally) helps me. Is there a way you would look at the diagram and see what is what? Or you just wouldn't do that because you would be following the prescribed diagnostic in VIDA with the car connected? That may be why Volvo doesn't describe the functions in the wiring diagrams if it's not needed, but for hackers like myself.

So with more testing today, I think I found it, I just started tapping some more wires and figured I would try out the Yellow/red wire. That seems to be it, 12V with the reverse lights on. The odd thing is the wire is supposed to be "YE/OG" which is yellow/orange. I tested the yellow/orange wire and that was def not it. But the yellow/red appeared to be it. Now I am color deficient in my vision, I have to use lots of light to see stripes. I had my daughter looking at the two wires next to each other she agreed it looked red and the other orange. Maybe I am not familiar with the vagaries of Swedish wire colors, but if I mistook the orange for red, then what is the orange? My wife thought maybe pink could look orange against yellow. I'd have to drop the bumper to pull the light and confirm, I don't want to mess with it so it may remain a mystery.

At any rate I think I got it and everything is making a bit more sense now.
 

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I'd need your VIN (or a VIN) to check the diagram. The new diagrams are lacking in a lot of aspects though.

If I get time at work I'll plug the VIN of another 19 S60 in and take a look. Sounds like you found it though.
 

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Discussion Starter #7
I'll PM you my VIN. Confirmation would be good, make sure I am using the system right ;-)
 
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