[ainarssems]

They do not give warning light on 1997 PF S8 coded beam. I don't think they would on foglights either.

CAN bus friendly kits are not about warning light but about making less electrical noise in power supply to avoid communication errors between different ECU's.

I had a battery failing on mine, would go flat in 3-4 days time and at that time when I switched HID lights on instrument panel would freeze up and CD changer stopped working. After getting new battery everything is fine.

I assume CAN kits have extra smoothing capacitors and maybe filter coils in them to reduce electrical ripple noise in power supply. CAN bus work with faster and weaker signals then older KKL and therefor is more susceptible to noise. On the other hand there is plenty of other things that make noise in the car - alternator, ignition coils, electric motors and even injectors and ECU's are build to cope with it.

I think that if the battery is good and you have good battery connection, ground connections and well generally all electrical connections then non CAN kits should not give any problems either.