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You are correct in what you are saying.When the brake is pressed the child locks stay engaged which prevents the doors from being opened from the inside.

What is
1) Child lock request and 2) Child lock detection?

Can you say disable the child lock request or enable the child lock detection while the vehicle is stopped?

Do, not however directly rely on the brake.

Speed needs to be in there somewhere or really distance. You get a pulse fromt he speedometer after every so many whatever is traversed, thus you can detect "vehicle isn't moving". Jaycar has a frequency switch.

so, disable the child lock request while the vehicle is moving which migh already be done. All you have to add is "disable the child lock request" when the brake is pressed. I'm assuming that the "child lock request" means "unlock the child proof doors".

Now, if those signals are say CAN bus signals then, your into major difficulties. If logic, you may be OK.

child lock request is an input signal to tell the child locks to lock. child lock detection is the state of the lock, ie locked/unlocked. The signals are not CAN.

So, does that mean you have the problem nailed? Basically disable child lock request when the brake pdal is pressed?