The analog clock stopped working in my 1995 XJS. I'm not sure exactly when it happened, but the first time I noticed it was shortly after I'd jump-started it, after not driving for a few weeks. I figured that either I'd blown a fuse or damaged the clock itself.

I pulled the clock out of the car and hooked it up to a DC power supply. It works fine as long as it gets more than about 9 volts. The clock is supposed to get 12 volts. So, the clock isn't damaged.

I reattached the clock and measured the voltage across its terminals. It measured 0.4 volts. That's very confusing to me. If the fuse had blown, or a wire had broken, I'd expect it to measure 0 volts.

Could the fuse have partially blown, creating a high resistance and therefore dropping the voltage?
Which fuse is the clock circuit on? I expected it to be on the same fuse as the clock illumination bulb, but that bulb works.
Any other ideas?

 

I solved the problem! I finally found a diagram that showed which fuse the clock was on:
http://www.justanswer.com/car/198n2-...-unpluged.html
Left passenger compartment fusebox, fuse 13, 5 A fuse. Replaced it and the clock started right up!

 

Good to know!