After the wash cycle completes the Rinse cycle will not start. Any suggestions?
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Inner door replacement parts for THERMADOR THD4800 | AppliancePartsPros.com
If the unit does this consistently it sounds like a timer problem.
If the timer just stops here it may be jamming for some reason.
You could try removing it and seeing if you can clean it and any linkages.
Could be a dirty/pitted set of contacts.
You did not say if you can rotate the timer and if it will then operate/finish the cycle or exactly what happens re: fill but no pump, no fill etc.
As you can see most parts on this unit are obsolete and getting any tech info on it is very difficult.