So I have been trying to fix my 2003 G35 coupe trunk latch for a few days now and have run out of ideas for what could be wrong. It doesn't work and doesn't have the right voltage (I'll get into that later). I have heard on other posts and forums that the wires that go out from the trunk in the rubber loom can sometimes get broken, I took that rubber loom off for now and have fixed all the broken wires in the trunk but the problem still persisted. Then I wanted to see if maybe the trunk switch might be the problem and when I took it apart I found that the previous owner had taken the positive off of the trunk switch and ran it directly to the fuse panel and just jammed a fuse on it. He also had soldered the trunk latch wires to the trunk switch (I'm not sure if the trunk latch wires are supposed to go back to the BCM or if they are supposed to go directly to the trunk switch). I also found that the fuse on it had been blown so that was probably the problem, however I want to wire it properly so that the fob still works (the fob also didn't work before). So I looked up some wiring diagrams and I thought that the positive of the trunk switch comes from the valet switch in the glove box. So I tried to find a wire that came from the valet switch to the trunk switch but there were none there that looked like they worked. So I temporarily just spliced a wire in from the valet switch to the trunk switch and tested it out and it didn't work. But I found out that the valet switch was outputting 4.6v to the trunk latch. From what ive read on other threads the voltage at the trunk latch should be 12v. I did make sure the valet switch was on before I did all of this and I tested the latch and it works too. So here are the questions I have
1. Is the trunk switch supposed to get power directly from the valet switch and is it supposed to go right from the trunk switch to the trunk latch? (it looks like the previous owner had soldered the trunk latch wire onto the trunk switch)
2. If the valet switch is supposed to go to the trunk switch and that is supposed to go to the trunk latch, why would it be outputting 4.6v and not just nothing or 12v?
3. If the trunk latch is supposed to go straight to the BCM, what wire is it supposed to connect to/how would I find the correct connecting wire?
Help would be much appreciated, if you are confused about any of this feel free to ask questions, Thanks!
It sounds like the previous owner did some mods...
Below are the 2 pertinent pages from the 2003 Coupe Factory Service Manual (thanks to nicoclub). The basic story is: the job of the trunk lid opener switch is to ground pin 76 of your BCM. The Valet switch simply interrupts that circuit disabling the main switch - so you can lock the glovebox and thus lock the trunk. When pin 76 sees ground the BCM then sends +12v out of pin 19 to power the actuator.
The reason the BCM is involved is so you can pop the trunk using the fob which is also supposed to tell the BCM to send +12 to pin 19. No idea where your 4.6V is coming from. Hope this helps.
Thank you so much for the help, I have been doing some testing over the past few days and I finally got this to work today. I'm not sure why the previous owner completely bypassed all this and rewired everything but when I tested out of pin 19 when grounding pin 76, 12v came through. I roughly wired everything up and the trunk switch and fob works! Also the 4.6v was coming out of the valet switch when it wasn't grounded.
It sounds like the previous owner did some mods...
Below are the 2 pertinent pages from the 2003 Coupe Factory Service Manual (thanks to nicoclub). The basic story is: the job of the trunk lid opener switch is to ground pin 76 of your BCM. The Valet switch simply interrupts that circuit disabling the main switch - so you can lock the glovebox and thus lock the trunk. When pin 76 sees ground the BCM then sends +12v out of pin 19 to power the actuator.
The reason the BCM is involved is so you can pop the trunk using the fob which is also supposed to tell the BCM to send +12 to pin 19. No idea where your 4.6V is coming from. Hope this helps.
