Anytime I start my XF by pressing the brake and start button immediately after entering the car, the light comes on but engine will not crank. Has anyone experienced this?
It only starts after disconnecting and reconnecting the battery.
What's the fix for this?

 

Have you tried pressing the brake really hard, like both feet & your weight on the pedal?

 

Yes I have, even locked and unlocked the doors, never worked.

 

Have you tried checking if there are any DTCs being reported?
Just so I'm understanding the problem, if you unlock the car, get in and try to start it the electronics come on but it doesn't attempt to start. If you then disconnect and immediately reconnect the battery it then tries to start?

 

Another thought, do the brakelights come on when pressing the brake, this will prove if the switch is working.

 

I have B1B33-87 DTC only.
When I disconnect and reconnect battery it starts.

 

Yes, the brake lights come on.

 

Sounds like the Passive Anti-Theft System (PATS) is active.

Firstly check that the PATS is working:

"The best method to confirm the correct operation of the Passive Anti-Theft System (PATS) is to check the LED (located in the center of the instrument panel). The LED should illuminate solid for 3 seconds, when the ignition status is set to ON, and then extinguish. This validates all PATS functions (i.e. the key transponder matches a stored key code, the challenge/response sequence between the respective modules was successful resulting in the EMS being enabled)."

Try this with the smart key docked in its cradle and see if that makes a difference.

The error code you are seeing seems to be from the instrument cluster, its not receiving the "enable" message from the ECM and therefore won't let you start the car.


Is the battery condition good? It could simply be that the voltage is too low for the ECM to power up properly. Voltage will drop a lot on unlocking as it moves all the door motors and wakes up all the car electronics. I'd check that first, iffy batteries cause all sorts of random electronic failures in these cars.

If you definitely know the battery is good then I'd look at the connections to the ECM, check for corroded connectors, that its getting sufficient power and a good ground, you can loose several volts over a poor connection.

 

Thanks for the detailed response.
Seems like PATS is active because this only happens when I start the car hurriedly without waiting for the sequence to complete.
Where is the key dock for 2013 XF (facelift)?
Any idea why an XF would smoke (black) after being driven for 2 miles but never smoke on idle? Like new engine, no CEL, engine torque or sound not affected, oil level ok

 

It should be impossible for you to get in the car and try to start it before it disarmed PATS, its at max 2 seconds after you've unlocked it. The reason its kicking up the error is that its not getting the message from the ECM in time, which is what leads me to wonder about the state of the battery or the connection from the ECM to the CAN.