Air Bag light on dash

I took the feed for the spotties off the red/yellow and black wires on the head lights. I didn't disconnect the battery.

you may have disloged a plug to the air bag wiring whilst running the wiring(air bag wiring runs in yellow sleeving )or it just had a bad day and needs to go back to the dealer to remove or reset the code.

I did unplug a connection on the steering column - on top of the key barrel that from memory had a yellow sleeve.
Can it be reset easily?

try disconnecting the battery (leave diconnected for at least 1 minute reconnect battery) if that fails it will have to go back to the dealer for reset