its difficult for me to say .. i cant see the car so am working on what you have posted .
Info ..
The car wont lock ..
So .. its either not seeing the signal to lock or its seeing something critical that it wont lock because of that.
No signal .. can be seen on a tester .. fob signal in alarm actual values .
Fob faulty or alarm not seeing the signal so antenna lead or faulty alarm control unit .
Critical items ..
If it thinks the key is in the ignition it wont lock .
If it thinks the drivers door is open it wont lock .
It will lock for pretty much every situation other than that but will beep if it sees a fault .
That sensor is pretty much just an led .. i guess it could cause this .. all i can say is i wouldn,t expect it to do this and ive never seen it before .
I have seen the faults ive listed though .
Drivers door lock can be seen on a tester .
Ignition key being seen as still in the lock can be seen on a tester.
Fob signal .. which will rule out the antenna lead and the fob .. can be seen on a tester .
As with all things we eliminate each posibility then move onto the next .
When we have proved all external parts are ok we replace the control unit as thats all thats left and its almost impossible to prove a control unit / software fault.
We eliminate things .
EDIT ..
The codes would help if you can get them .
Info ..
The car wont lock ..
So .. its either not seeing the signal to lock or its seeing something critical that it wont lock because of that.
No signal .. can be seen on a tester .. fob signal in alarm actual values .
Fob faulty or alarm not seeing the signal so antenna lead or faulty alarm control unit .
Critical items ..
If it thinks the key is in the ignition it wont lock .
If it thinks the drivers door is open it wont lock .
It will lock for pretty much every situation other than that but will beep if it sees a fault .
That sensor is pretty much just an led .. i guess it could cause this .. all i can say is i wouldn,t expect it to do this and ive never seen it before .
I have seen the faults ive listed though .
Drivers door lock can be seen on a tester .
Ignition key being seen as still in the lock can be seen on a tester.
Fob signal .. which will rule out the antenna lead and the fob .. can be seen on a tester .
As with all things we eliminate each posibility then move onto the next .
When we have proved all external parts are ok we replace the control unit as thats all thats left and its almost impossible to prove a control unit / software fault.
We eliminate things .
EDIT ..
The codes would help if you can get them .