Bosch-dishwasher-heater-relay-repair-part-1


Video shows how to replace a defective heater relay on a control board module for a Bosch SHE44C dishwasher. The heater relay overheats the solder connection on the control board and eventually the dishwasher will no longer heat the water. This problem results in the dishwasher seeming to never finish. Sometimes the panel will show a "1" to indicate that the water is not heated sufficiently. This repair is applicable to many models. Always disconnect electrical power before working on your dishwasher. Also, check to see if your unit is part of the Bosch recall before you attempt repairs...mine was not listed. WHY the relay must be replaced is found here: http://www.youtube.com/watch?v=3nLN3WO3RQY 

In simple terms, a relay is an electric switch that is operated by an electromagnet.  The coil voltage is the voltage at which the relay is designed to operate the switch.  When an electric current is passed through the coil it generates a magnetic field that activates the switch, which in turn passes current to the load (in this case the heater).  As the relay is energized and de-energized, arcing takes place at the contacts.  This arcing is what wears or burns the relay contacts and eventually results in failure.  All relays have an expected lifetime... they are an electromechanical device.  In general, the closer the load current is to the maximum rated contact design current, the sooner the relay will fail.

Please note that Bosch manufactures some models that use a heater relay with a 12V coil (a few boards may have a 9V or 24V coil relay, but they are more rare). The coil voltage is usually shown on the relay or in the part number. Also, a 12V relay has a coil resistance of 400 ohms while a 6V relay is 100 ohms. The R46-5D12-6 is a 6V coil relay. If your control module has a 12V relay, use R46-5D12-12. The "-6" and the "-12" identify the coil voltage. If you are not sure which relay you have just post the part number found on the top of the relay here and I will help identify it for you. Cheers!

Disclaimer:
Any information written here or included in this video is simply my opinion and is not professional advice. Your use of this information is at your own discretion and risk. You are advised to do your own due diligence before attempting any appliance repair.

P.S. 
Since posting this video, Mouser no longer stocks the R46-5D12-6. Search some of the many other sources mentioned in the comments below.

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