Bosch SHE55M16UC/64 water fill issue

[mguilbau]

I have had quite a difficult time with a dishwasher repair.  It began with an error that my heater was not working so I was instructed to replace the control module.  That did not fix it.  I then replaced the heater, again, not repaired.  I checked and I am getting 120 volts to the heater but the unit did not engage the heater.  I finally figured out that not enough water was going into the dishwasher to make the heater turn on the switch to allow current to flow.  So what started out as a heater error, really is a water fill issue and I am now trying to diagnose that properly.  I have a time fill system to manage the water flow into the machine and I am wondering what is the best way to troubleshoot this problem.  I can change out the water intake value in the hopes that is it but I would rather not just replace parts without a good reason.   I am concerned because this could be a time fill issue, an impeller issue, or a fill valve issue.  What do you suggest to replace or test first?

Many thanks in advance for any help!

[Samurai Appliance Repair Man]

As with any computer-controlled appliance, you have to start by talking to the computer to let it tell you what it thinks is wrong and to run unit operations. This informs your troubleshooting strategy where you would then use the schematic to confirm which component is out of spec. You'll need the service manual for this: