Keyless entry problem diagnosis/fix

[jdhx]

I have now signed up for Orbit. 

There are no DTC's stored apart from:

ECM-P106107 Power pulse system leakage

I guess that says that one of the turbo hoses needs replacing which is good to know!  Is there any way to know when this DTC occurred?

I tried resetting the VCM and CEM ecu's but that made no difference.  I have also looked through the data available from those two ecu's but I can't find anything that might help identify a faulty antenna or other issue but then I don't know what I am looking for and there is loads of data.

I looked thru the car's config and the number of keyless door handles is undefined which I guess is benign.  I don't have the CEM pin so I can't try setting it to 4.

To quote Power6 from the last post, I certainly don't know what I don't know.  What I do know is I am not getting anywhere but perhaps learning a bit about the car.

[jdhx]

UPDATED:

I located and unplugged the keyless antenna in the boot/trunk area and that caused a DTC to throw.  When I press the tailgate "close and lock button" nothing happens.  Previously (ie with the antenna plugged in) I would get a "can't find key" beep beep beep, now nothing.

So I have proved that missing/unplugged antennae do cause a DTC but that does not mean much.

The keyless lock/unlock still works sometimes,  maybe I should buy a new key and add it to the config to make sure it is not the existing keys failing. That said, I have 3 keys that fail. It still works intermittently but without any pattern although the longer the car is left the more chance it will unlock keylessly. One of the signals must be sometimes just strong enough. The same happens to keyless start, at the moment half the time the key has to be placed in the emergency position in the centre console and half the time it works from my pocket. Weird.


For the record, the boot/trunk antenna is located in the centre of the car, directly below and just behind the rear centre seat back.

Any ideas anyone?

[vcorusa]

I had similar issue, when car was sitting for longer time, like for 2-3 days, it wouldn't unlock on key press. Once it unlocked it worked every time, until car is left to sit for longer time again.

Issue was fixed by changing the remote battery, I used Duracell.

[András]

Here is one thing I figured out; if the key is in my bag, next to my mobile phone, the keyless entry fails sometimes. Especially on the trunk close button. I do not know the exact reason, but the phone interferes with the key's signal. 

If that is not the problem, I have an other idea. Do your keys have motion detection? Maybe try shaking it around a little while trying to open the car and see if that changes anything.

[jdhx]

Thanks for the comments.  My problem is different in that the key presses always work but the keyless entry hardly ever does.  It is totally random and it makes no difference where the key is at the time.

My current thinking is that the car's sensitivity has dropped just a little which would explain why all three keys fail to work keyless.  I know that when a handle is touched the keys close by do respond with their coded signal effectively saying "I'm here".

The car is booked into a Volvo indy tomorrow, hopefully they will diagnose the issue once and for all.

Thanks

[IMAY2023]

I have a different problem but I think it's related to detection of the key location. The car is supposed to warn the driver if the engine is shut down and driver door is opened while the keys are still on the center console. My car sometimes warns me and most of the time it does not. It does not bother me that much but I think it has something to do with antenna or a software glitch.

[jdhx]

So an update.

VIDA does not identify any reason for the non working keyless entry.  However, I obtained another fob from ebay and programmed it with OrBit and the keyless locking/unlocking with that key works.

The new key is the MS type and although OrBit  programmed it OK, it did throw a dtc (CEM-B14DE05) which OrBit did not clear.  The VIDA diagnosis suggested that the CEM needs new software but that is apparently only available with the purchase of a new fob with a total cost of about £200.  That is the current price but the Volvo indy told me it varies with the wind as Volvo have introduced lots of changes, presumably to try and stop the relay thieves.  Volvo (in the UK at least) say get your car serviced by a Volvo dealer and the software will always be the latest, what nonsense!  It is time that the UK have "right to repair" laws like the US.

Along the way I did some checks and measurements and discovered that the new MS key sends a slightly higher 433MHz signal than the old keys, something like 3db, when the door handle is touched.  I have concluded that the car's sensitivity has dropped a little over time which is why all the old keys no longer work and the new MS key does. And yes I have checked the batteries of the old keys, they are all duracell or varta and the voltage is > 3.1v.  Actually the voltage of the new key battery is less than the old ones.

So for the time being at least - it's SORTED.