L322 keyfob signal not received

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Lost comms to the RF receiver wouldn't by itself cause the key not to be recognised and give start authorisation once in the car.
 
Graculus said:
Comms to the RF receiver wouldn't by itself cause the key not to be recognised and give start authorisation once in the car.
Click to expand...
Sorry I'm a bit lost now.. but I'm tired too.
If the rf isn't getting sent down the wire then surely that's why i can't lock/unlock our start the car without placing the fob on the nfc point?
 
Check the pin grip on the KVM, particularly to the RF receiver, also check the RF receiver for moisture ingress, +ve & ground connection (and voltage when connected), although I suspect it will be OK and the causal part is the KVM itself, due to the other five antennae not detecting the key inside the car, regardless of the 'active' (key buttons) doing nothing and loss of comms to the RF receiver.
 
Graculus said:
Check the pin grip on the KVM, particularly to the RF receiver, also check the RF receiver for moisture ingress, +ve & ground connection (and voltage when connected), although I suspect it will be OK and the causal part is the KVM itself, due to the other five antennae not detecting the key inside the car, regardless of the 'active' (key buttons) doing nothing and loss of comms to the RF receiver.
Click to expand...
The kvm i think is the black box in the boot? I can do that.
Getting the dash out for the rf receiver songs like a massive job so will be next weekend at the earliest :(
 
The KVM has two functions, to process the unlock signal and authorise the CJB to unlock the car. Once unlocked and the key is inside, it sends pulses through the five interior antennae to ask the key to validate itself, these antennae switch to receive and grab the rolling code from the key, which the KVM checks, then sends the 'start authorised' message to the CJB on MS-CAN.

In your case, neither function is happening, you've ruled out the key, as neither work reliably and you can only start the car by placing the key against the dash. This is crucial, as that NFC antenna is connected directly to the CJB, not the KVM, so effectively bypasses the KVM and re-initialises the rolling codes - which may be where the problem lies, if the KVM is becoming 'forgetful' and not incrementing either the unlock or start authorisation correctly - the 'lost comms to RF receiver' is most likely an internal KVM defect but it's be worth checking the wiring is OK before going any further.
 
kermit_rr said:
The kvm i think is the black box in the boot? I can do that.
Getting the dash out for the rf receiver songs like a massive job so will be next weekend at the earliest :(
Click to expand...
The RF receiver for the key lock/unlock is above the headlining, not the dash - that is the NFC one and from your narrative, mosdt likely not the causal part as it only connects to the CJB, not the KVM
 
Hmm... Just done a bit more digging - there is some contradiction in the documentation, the latest I've read has a different configuration, which narrows down things somewhat and explains how your DTC can explain both active & passive not working.

"At the request of the CJB , the KVM prompts each of the LF antennas to output a signal. When the Smart Key is in the vehicle
cabin, it detects the LF signals and responds with a RF data-identification signal back to the KVM via the RF receiver."

So the RF receiver is used to both lock/unlock the vehicle and grab the validation for the start authorisation, check the KVM for corrosion or loose contacts, if OK, then I'm afraid you're going to have to get to the RF receiver above the headlining
 
Well the little green gnome must have been on a bit of a bender at the pub last night because he's not been round to catch the gremlin this time
 
Well rather than playing 'will it? won't it?' I think you'd be wise to spend a bit of time checking out the KVM & RF receiver wiring electrical supplies & pin grip - and a good look around for signs of moisture ingress or chafing of the harness' while you're there.
 
Yes I'll check out the kvm and other modules in the boot this morning
I'm wondering if i can reach the rf receiver by removing the rear/central dome light rather than dropping the headlining. At least for a look and a poke
 
Plus the battery is now dead.. would leading it in the wrong way, kill it?
I can't see how it's related to the core issue, unless a bad signal could somehow crash the kvm? And it resets itself some hours later?
I've never had 'batt low' on the dash and never thought to check.. plus with the other fob not working assumed it was not a battery issue (batt in the other fob is good)
 
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