Intermittent unlocking / key ID issue

[calnorth]

I have some diagnostics for the Intelligent Key (I-Key) system. Not that I could do anything much with it. What you appear to indicate is intermittency of the I-Key to Body Control Module (BCM) communications. I'll try to express some logic here: (some shooting in the dark)

1. Usually key problems are I-key Battery related but you have 2 keys showing same problem. So a Batt power error is unlikely as is corrupt I-Key code activity. The key codes are supposed to be rolling (changing) codes per start activity. 2 keys behaving the same way indicate unlikely code problems?

2. Unlocking and Ignition functions use antenna pickup of the I-key signal that has been validated (or not) by I-key processing. Thats an antenna in the door handle (outside antenna) and ignition button body (inside antenna). I don't think the problem is with those antennas from your behaviour descriptions.

3. Communication from the I-Key when verified by internal I-Key decoding is communicated to BCM by the inside antenna and cabling. The car at that point has to be in a prescribed state that is determined within BCM as far as I can tell. Not sure what the conditions are in total but things like bonnet lock/door switch/brake and clutch pedal status is mentioned. I believe BCM here validates that the I-key is correct for this car. That arises from initial I-Key registration.

4. For the error message ‘Invalid Key ID’ to appear in the centre screen, communication needs to be ok. So the suspect area moves away from communications via antennas to BCM itself and the Engine Control Module (ECM). Verification to START is performed by communication between BCM and ECM when BCM fully validates the I-key and car state.. The conditions to START now move to both car state and including engine state.

Problem here is that I cannot tell exactly what flags up ‘Invalid Key ID’ . And I've seen it arise at odd times on my 2017 QQ, usually when I'm just outside the open driver door with the key in my pocket. It self corrects though.

It would be easy to say here that BCM has lost its registration data but the intermittency of your problem probably indicates an error sensing the condition status of various switches mentioned above? I won't speculate further. Its likely DTC's (error codes) are raised for the dealer - OBD (diagnostics). Sorry to hear that you have been seriously hit by the current over stretched madness.

Operation:
BCM controls INTELLIGENT KEY SYSTEM (ENGINE START FUNCTION), NISSAN ANTI-THEFT SYSTEM (NATS) and VEHICLE SECURITY SYSTEM.
BCM performs the ID verification between BCM and Intelligent Key when the Intelligent Key is carried into the detection area of inside key antenna, and push-button ignition switch is pressed. If the ID verification result is OK, ignition switch operation is available.
Then, when the ignition switch is turned ON, BCM performs ID verification between BCM and ECM. If the ID verification result is OK, ECM can start engine.

[lewisbryant]

Can you post picture of the ikey board please?

[Teknaman]

Thanks for all that info calnorth - much appreciated.

lewisbryant - do you mean a pic of the circuit board in my key fob? If so, just one or both? Thanks

[lewisbryant]

Yeah the board and one of them will be alright which ever is worst or most commonly used

[Teknaman]

Hopefully 3 images attached (from both keys)? Cheers

[calnorth]

@lewisbryant...from my understanding of what @Teknaman has said above and from the start, both Fobs appear to be disrupted in the same ways. Inconsistent/unreliable unlock and ignition operation. I expect both to trigger Key ID recognition failures also.

Whats on the rear of the board?