I am assuming it is Hardie (irritrol) Total control timer?
Usually, if the timer is older...the back panel goes bad.....I would just replace the timer.....sometimes on the back panel a solder connection gets shorted...
but: try this first....disconnect power to timer and remove battery...wait 30 seconds then hook up power and then new battery.....try to run manually after that...if still says short...probably bad timer....sorry
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