Boot unlocks when ignition is switched off

[Big_D]

I am hoping for some help with a problem I am having with my daughter's K12 Micra S. It is a 2003 model, fitted with the Intelligent key system.

It all started with the boot opening while my daughter was driving. The fault was traced to water ingress into the boot switches (the common Micra fault). Before this, everything worked fine with the locking system.

As she needed to use the car, I stripped the switches down, and did a temporary repair. The lock then worked fine. Ray=ther than wait for the temporary repair to fail again, I bought a replacement switch set. I have now fitted the new switches to the car, and now the boot will not open when the button is pressed. I can lock, and unlock, the car with the top button, but the bottom button will not open the boot. I disconnected the new switch, and re-fitted the repaired switch, which does exactly the same. When I turn the ignition on, I can open the boot with the bottom button.

To test everything, I tried disconnecting the white plug, and shorting out the two contacts. The boot will not open.

When I turn the ignition off, the boot now unlocks itself.

I have checked all the wiring, and no wires are broken. Everything seems to be fine wit the wiring. Key fob has new batteries, and main battery pf the car is good.

Why can the boot only be opened with the button when the ignition is on, and why does it open by itself (without pushing the button), when the ignition is turned off.

 

[Master tech]

Sounds like it could be a broken wire between tailgate and body or a bcm fault.

 

[Big_D]

Thanks for the reply. I have already checked the wiring, and nothing is broken.

How would I test the BCM, and where would I find it?

 

[John_D]

Thanks for the reply. I have already checked the wiring, and nothing is broken.

Unless you have stripped back the loom in the area you won't know if it is damaged. I made the same mistake when the boot lock on my K12 started playing up. I peeled back the rubber convoluted cover and the loom underneath looked pristine. It wasn't till I later cut back the loom wrapping tape that I found the broken wires......

 

[Big_D]

I peeled back the convoluted rubber, and stripped off the insulating foam. Each wire was physically checked and nothing is broken. I've checked all the earth wires, and everything seems fine. I even went so far as to check the loom all tje way down to the switch connectors. Definitely no break in the wires.

I am at a loss as to what could be causing the problem.

 

[John_D]

Sadly the BCM seems to control much on the K12. When the rear wiper on my K12 stopped working I could also find no physical fault anywhere, then found it was controlled by the BCM. A hard re-set by disconnecting the battery for a few minutes did the trick and the rear wiper started working again and has never gone wrong since (over a year ago)........

 

[Big_D]

Thanks John_D. I'll give a hard reset a try. I did remove the fuses (F6 and F17) for the central locking and immobiliser functions and this didn't help.

I'll try a proper hard reset this afternoon and let you know.

 

[Big_D]

I finally managed to get the car tested today, and the hard reset worked. The boot lock is now not opening wen the ignition is switched off. But there is now a further problem. The car will now not lock the driver door with the remote. When I push the lock button on the boot, everything locks.

Thanks for the help and advice

 

[John_D]

This might be worth trying. Looks like the key has lost it's unlock programming.....