Does anyone know what this knob does? It's on the dashboard of a 1969 xke.

 

Welcome to the forums wrt,

I've moved your question from General Tech Help to E-Type forum. Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Normally the brake fluid light would be in this location and, to its left, would be the headlight dimmer switch. So, first question, where was that switch relocated to? Just a guess, your extra control might be for windscreen wiper interval setting added by a previous owner.