Thread: P1668 BCU serial link timeout fault

Just surfing and found this....hope it helps:

Fault Code P1668 - Land Rover Repair Forums - LRRForums.com

Good luck...

It's interesting to read. From what I can gather, and mine does this, if the passive immobiliser is activated then if you don't start the car soon enough after pressing the buttons then it will rearm and you need to push the button, potentially after removing the key but mine I just turn the key back and press and then start.

Many thanks GEK064 and clubagreenie for your help.

Clubagreenie, which button do you press, the lock or the unlock button on the key fob? LRT

Unlock, seems to reset the alarm. Haven't paid attention to the light on the dash though as mentioned in the report.

Thanks clubagreenie for you helpful tip. I tried pressing the unlock button on the key fob, and tried to start the car, but it still wouldn't start.

I went into the ABS Circuit Tests menu on the Hawkeye diagnostic tool and tested Supplies and Grounds, which passed. Then I tried to start the car again and the engine started instantly.

As the problem started after driving on rough gravel roads, it probably has a short or an open circuit somewhere in the BCU or CAN data bus wiring.
Any clues?
LRT

I've had 3 amigoes regularly, then none then some after an off road trip which was resolved with a good wheels off clean of the hubs. But it's never affected the starting. The contrary, turn off & on would reset the lights.

Possibly something unrelated in the SRS system which if active may stop starting. Or it's still something in the alarm/immobiliser system.

Sorry I can't help further.

Edit: See if you can borrow a D1 and try to swap out the ign barrel. There may be an issue in there? It's also a cheaper (much cheaper) replacement than a D2 version.

Thanks clubagreenie for your advice.

I have the three amigos regularly. Turning the ignition off and then on fixes the problem for a while, but usually the amigos reappear. The amigos also come on after the traction control has been working.

The fault that comes up is: Fault 4114 shuttle valve switch failure electrically super vision. The ABS Live Data also states there is an Open Circuit.

Also, around the time the problem occurred, the ignition barrel wafers seized. I spent an hour tapping the barrel and lubricating it with WD40, before it started to work again. I will squirt some SRC contact cleaner inside the barrel to clean the electrical connections.

Regarding new ignition barrels, can you modify the new D1 barrel to suit the original key that came with the vehicle?

LRT

You can, just need the locksmith to re-wafer it.

As an aside, I tried the spare key today, it doesn't have the key in the fob. If left long enough you need to press the button. I'm working on the assumption your key is in the fob also?