Power Trunk works….kinda - 2015 ultimate

[Scokeing]

My 2015 sedan 3.8 Ultimate is having power trunk closing issues.

The Good: Works fine from inside, will open and close power trunk from dashboard button fine. Will open using remote button, or using smart trunk feature.

However trying to power close when pressing trunk lid button either the power close or power close with lock button on the trunk lid I usually get nothing.

If I very slowly manually close the trunk, simultaneously pressing either close or close lock button, about have way closed the motor kicks in a closes and locks just fine. only tried that a few times, I typically close from inside switch as not to damage the motor.

I read up on the PTL having a position sensor, integrated hall sensor within the drive motor. Curious if that may be the fault. I looked up the part for this assembly 81800-B1000 and it’s pricey so before I experiment, curious if anyone else had a similar issue and knows the fix.

Thanks
Scott

 

[joegr]

You can try this.
Open the trunk fully. Press and hold both the open button on the outside of the trunk and the close button on the inside of the trunk at the same time until it beeps a few time. Now close the trunk completely by hand. Then press the open button on the outside. Let it fully open, then see if it will close from the close button on the inside of the lid.

 

[Scokeing]

Tha

You can try this.
Open the trunk fully. Press and hold both the open button on the outside of the trunk and the close button on the inside of the trunk at the same time until it beeps a few time. Now close the trunk completely by hand. Then press the open button on the outside. Let it fully open, then see if it will close from the close button on the inside of the lid. Joegr

Thank a lot for your reply!!
I agree your process should help sync the system. When I got to the press both trunk buttons (outside & inside) I never got a beep. I held for a significant time, I tried a few different ways, with key off, acc, and run mode as well, none would provide the beep. Unfortunately still no power close from the trunk lid switch. Did I miss possibly something in your explanation?

 

[joegr]

Tha

Thank a lot for your reply!!
I agree your process should help sync the system. When I got to the press both trunk buttons (outside & inside) I never got a beep. I held for a significant time, I tried a few different ways, with key off, acc, and run mode as well, none would provide the beep. Unfortunately still no power close from the trunk lid switch. Did I miss possibly something in your explanation?

No, I think that was all correct. Here's the exact wording from the service manual.

(1) Press the trunk inner switch
(2) Press the trunk outside hand switches at the same time
(3) When pressing 3 seconds of more, a buzzer sound is issued one time.
(4) Close the trunk manually
(5) When using the outside hand switch to open the trunk, the initialization is completed with a buzzer sound.

Maybe whatever fault you might have is preventing this procedure from being initiated?

 

[Scokeing]

No, I think that was all correct. Here's the exact wording from the service manual.

(1) Press the trunk inner switch
(2) Press the trunk outside hand switches at the same time
(3) When pressing 3 seconds of more, a buzzer sound is issued one time.
(4) Close the trunk manually
(5) When using the outside hand switch to open the trunk, the initialization is completed with a buzzer sound.

Maybe whatever fault you might have is preventing this procedure from being initiated?

Joegr
Thanks for the detailed procedure, I agree something else is preventing the reset.
A very strange activity is going on and I am going to have to remove some trunk panels to verify. When I open the unlocked driver door first thing in the morning I hear a small motor noise coming from the trunk area. Not sure if it’s related but it’s very strange that just a door open would excite something in the trunk area.
If I get some time this weekend I will take a closer look.
Thank much
Scott

 

[joegr]

...When I open the unlocked driver door first thing in the morning I hear a small motor noise coming from the trunk area. Not sure if it’s related but it’s very strange that just a door open would excite something in the trunk area.
...

Could that be the fan on the amplifier for the audio system? I know that parts of the system power up when you open the door, but I don't know if the amp is one of those.

 

[arcman]

That noise is normal. Part of the EVAP/Emission Control. So those nasty gasoline fumes don't go out to pollute our air.

 

[Suburbazine]

That noise is normal. Part of the EVAP/Emission Control. So those nasty gasoline fumes don't go out to pollute our air.

Close, it's the low pressure fuel pump module priming the high pressure pump for startup.

 

[joegr]

Close, it's the low pressure fuel pump module priming the high pressure pump for startup.

I really, really don't think that the fuel pump in the tank powers up before you press the start button. That would be a safety issue among other things. I know that mine never has. Note what he said:
"When I open the unlocked driver door first thing in the morning I hear a small motor noise coming from the trunk area."

For what it's worth, I'm skeptical about any emissions activity happening at that time either. I gave my theory on it...

 

[Scokeing]

Update, it’s better, I decided to disconnect the battery then retry to acquire a beep (pushing both trunk buttons) and was successful however not in a fully open position, it would beep when I closed the lid a bit. I tried the sequence numerous times at fully open position but would not beep.

I’m close, it did work perfectly once. However in subsequent close attempts it would not lower with either button push. But if manually closed just a bit both close and close/lock powered the close operation.

Possibly I trained the stop limit when the button beep process not at the top (that’s where I could acquire a beep)? I can use the trunk button after a nudge of the trunk down, so it’s better.

at least it’s not an expensive trunk motor replacement