I have a 2008 G35 sedan with a trunk that can only be released using the emergency release. I've tried the following:
1) I checked the continuity between the plug on the release motor fixture and the connector in the rear, driver-side fender. There was continuity on all three wires (purple, black and green) so the common problem related to a broken wire does not seem to be the cause.
2) I removed the trunk release motor from the trunk lid and verified that the motor spins when 12 volts is applied.
3) The valet switch is set to ON.
4) The trunk button, release switch by the driver's left knee and the key fob were tried.
I understand that since the open signal originates from the ECM, there is no fuse to test.
One odd symptom before the trunk lid release stopped opening was that for the past month, the trunk would sometimes unlatch on its own.
Thanks for reading this far!
Jeff

 

The signal comes from the BCM, not the ECM.

You verified the trunk cancel switch inside the glove box is turned off correct? This will 100% disable the trunk from opening from ANY button including the fob. Try it in the other position also.

Since you were experiencing trunk malfunction I would still suspect a wiring issue. Does it give you the 4 chirps when you hit the trunk release? This would indicate that the BCM is at least TRYING to open the trunk.

You could also disconnect the trunk opener harness and use a digital multimeter to measure for voltage on one of the pins while the trunk switch is actuated. Might just be a bad trunk actuator.

If you're not even getting the signal to the actuator I'd suspect maybe something wrong with the cancel switch. Remove it and test with a digital multimeter see if it opens/closes the circuit as you actuate the switch.

 

You verified the trunk cancel switch inside the glove box is turned off correct? <<yes>> This will 100% disable the trunk from opening from ANY button including the fob. Try it in the other position also. <<Tried but no go>>

Since you were experiencing trunk malfunction I would still suspect a wiring issue. Does it give you the 4 chirps when you hit the trunk release? .<<No chirps>>This would indicate that the BCM is at least TRYING to open the trunk.

You could also disconnect the trunk opener harness and use a digital multimeter to measure for voltage on one of the pins while the trunk switch is actuated. << Unexpected result see below >>

The actuator connector #B303 has three wires, a (1)Purple, (2) Black, and (3) Green. From the schematic on page DLK-164 of the FSM it looks like terminal 3 triggers the motor and 2 is the ground. I'm not sure why there is a third terminal since the actual motor only has two terminals on it.
Result with car off and switch at driver's left knee NOT depressed:
Pins 3 and 2 around 12 volts with 2 being -
Pins 1 and 2 around 10.5 volts with 2 being -
Result with car off and switch at driver's left knee depressed:
Pins 3 and 2 around 12 volts with 2 being -
Pins 1 and 2 around 10.5 volts with 2 being -
There is a slight increase in voltage with the car running.

I'm assuming the problem might be related to power being sent all the time to the motor but the motor is not running all the time.
I did notice a sound like the motor running briefly when I plugged the 16-pin connector in the fender back in while checking for continuity in the last segment of the harness that leads to the actuator.

 

Searching the FSM I found on pg DLK-98 I found a diagnosis procedure. It calls for accessing the BCM. Its too late to work on it right now so maybe tomorrow night.

 

Its the weekend so it's time to be the weekend mechanic:
I started the diagnostic procedure starting on page DLK-98:
Component Function Check
1) Check Trunk Lid Opener Cancel Switch
- I removed the glove compartment and check for continuity with the switch on and off.
- - The switch appears to work properly
2) Check Function
- I was unable to perform test as it requires a CONSULT-III to perform test

Diagnosis Procedure
1) Check output signal
- Checked voltage between terminal 23 and ground with trunk lid opener switch on
-- No voltage, appears to be grounded (PASS)

2) Check Trunk Lid Opener actuator circuit
- Ignition off, disconnect BCM and trunk lid lock actuator connector and check for continuity between BCM connector and lock actuator connector contact terminals 23 and 3, respectively.
-- Continuity confirmed (PASS)
- Check continuity between BCM connector and ground
-- No continuity is present (PASS)

At this point, it sounds like the BCM is not working properly. Should I pick up a used one to test this out since I don't have access to a CONSUT-III?

 

seems like you have the parts cannon aimed in the right direction!

 

I'm in the process of purchasing a used actuator because when I plug its connector in at the BCM, it makes a little noise but doesn't release. When I disassemble the actuator and apply 12v to it, the little motor in it spins. I'm assuming the actuator does not have enough power to actuate after being continuously powered. If the replacement actuator opens the trunk when I plug its connector in the BCM without pressing the trunk release, then I know the actuator failed but likely was damaged by the continuous 12v signal.

At that point I'll have to look at the BCM which is upwards of $600 new $75 used. Is a used BCM reliable?

 

Before you start replacing parts, pull the rubber boot on the driver's side between the trunk lid and the body. Push it back as far as you can from each end at a time and check for broken wires by tugging on them. You may have a wire with most broken strands. This will show continuity on the meter, however there is not an adequate number of strands left in the wire to carry the current required to activate the trunk release. I ran into the same issue with my coupe. The wires bend back and forth every time you open and close the trunk lid. There is not enough slack on the wiring harness to properly hinge the wires, so after some time they have the tendency to start breaking strands.

 

I thank you for you input but I don't think that is the problem. I pulled back the corrugated boot at both ends and gave the individual wires a tug. There didn't seem to be a loose wire. Also, the presence of a continuous 12v current in the green wire is a concern because I think that there should only be a current when a signal is sent by the BCM to open the trunk.

Does anyone know if a BCM needs to be programmed or will it work as received if I order a new one?

 

Or what's more likely is wires in that flex section have broken and shorted against one another which is what's probably supplying the 12vdc on that green wire.

99% of all trunk issues (brake lights, parking lights, trunk actuator, trunk courtesy light, etc) on these vehicles are broken wires in the flex wire loom.

I would definitely start by taking apart the loom and visually checking each conductor, then giving each wire a little bend/twist to feel for a soft section where you can feel the wires broken inside. It's usually pretty obvious once you get the flex loom out of the way if you have a broken wire issue, the insulation will be all cracked or sometimes missing in places, wires touching other wires, etc.

 

As for the BCM, yes it will require dealership programming to mate the ECM, BCM, and program your keys.

Used BCMs are fine, just make sure you get the exact part number, there will be two alphanumeric numbers in the corner near where it says NISSAN. Make sure those match.

Typically you would want to first source a used BCM, then schedule an appointment with your local Nissan/Infiniti to have them program it. Drive your vehicle to the dealership and ask then where they want it parked, then disconnect the battery and swap the BCM in the parking lot prior to your scheduled appointment.

Depending on the dealership and their work load it's typically better to just drop the vehicle off and come back later unless you want to sit in the lobby for several hours. Just talk to the service manager ahead of time so you know what to expect.

 

I'm sitting at an Infiniti dealer right now with the car in service. I gave them the background and asked to verify if the BCM was faulty. The best price I could find on line for a used BCM with the exact match was over $100. New ones can be had for $575 from a few on-line dealers so I'll likely spend the extra bucks for a new one. The diagnostic fee will count towards installation which should be quick since I have all the panels pulled off for them.
One more question: Who are the tiny hunters in your photo? I was confused by the scale until I saw the curb.

 

Ok here's the story, for my son's first birthday my grandma bought him a pack of those G.I. Joe action figures. He was WAY too young to be playing with those things but I didn't want to hurt grandma's feeling so we just played it off.

As soon as we got out to the car I took them away from him, then I saw that dead squirrel behind our car. First I was just posing them on the squirrel, then my wife saw what I was doing and gave me the camera that her dad bought as a wedding present and we started taking pictures. They're all pretty shitty quality because this was over 20 years ago, I've been using that particular photo for my avatar on every website since.

What's really funny is I've seen some of those pics floating around on the internet still, I think I took like a dozen different pics. I emailed them to some of my friends that were over in Iraq later that year and I think it was one of them who posted the rest on the internet. So the rest of those pics with those two action figures were unofficially posted to the net via the US Marine Corps

 

Cleric670... You need to make that story a sticky...

I'm back from Infiniti and what happened was the drains in the sunroof clogged causing some water to drain into the cabin. Not enough for us to notice but enough to damage the BCM. So, it was the BCM. Luckily I had printed a copy of a price quote for the BCM from the very same dealership. The repair quote showed $750 for the BCM but the on-line price at the dealer was $535. At least it was that price when I printed the web page on Monday. The price on their web site is back up to $750 but I showed them Monday's printout and they agreed to match that price.

They also found an oil leak I haven't noticed before. There is an oil leak from the engine oil cooler gasket, whatever that is. I'm going to take a look at it myself before having them repair that for another $366.

Thanks for the help.

 

I just looked up the oil cooler gasket replacement and it's not much more than changing the oil filter so I think I'll save $366 and DIY it.