Got side tracked a bit on this while using a power probe.
It came in on a tow with clicking from the engine bay and cluster flashing as though the battery was flat.
Running over the fuses with a power probe battery voltage was measured at 12.3v but the red led light pulses off and on in time with the clicking!

Probe managment relay. led flashing, probe 30 pin, still flashing on and off. Trace circuit,feed from ignition relay, probe 87 and 30 still flashing. Lift fuse box and probe main supply, Still flashing!?
Put away probe and get out scope, connect up to ignition relay and realise my mistake!
Voltage is not dropping of but actually going up from 12v to about 20 then back to 12!
Power probe light is going off because it is not reading battery voltage!
Sorce of clicking and voltage peaks... throttle body!
Made me smile