I have actually been on a service call where the customer had hired another servicer to repair this problem. The other servicer, obviously merely a parts-changing monkey and not a real technician, simply slapped in a new heating element, didn’t bother to check his work, collected his money, and left. I asked the customer why she didn’t call him back to repair the problem for which she had hired him in the first place. She said he was too hard to reach, has left several messages with no return call, and she’s rightfully concluded that he is simply an incompetent cockroach and she wanted to try someone else.
Now, in the Bosch dishwasher, one indication that there’s a problem with the water heating circuit is if the dishwasher takes forever to complete a cycle. Note that “problem with the water heating circuit” does not equal “bad heating element.” While it’s true that the heating element is part of the water heating circuit, it is only one of several parts which can fail and kill power to the heating element. “How can we tell this?” you ask, incredulously. Well, Slick, a real technician uses a multimeter to make some simple electrical measurements so that he can determine, with absolute certainty, which part is bad. No guess work involved here. No replacing a part and hope you get lucky. Real technicians do something called “troubleshooting” in order to prove which part is defective.
So I pulled the wiring diagram for the dishwasher and measured the continuity of the heater and the heater’s thermal cutout fuse– both were good. Therefore, I knew that the problem had to be in the control board. So I opened the control panel, pulled the control board out and, walla!, found a burnt solder joint at the heater relay. How ’bout them apples? In case you haven’t already figgered it out, you can click the picture for the larger, annotated view.
So I got my solder gun from the van, soldered the connection, popped the board back in and ran the dishwasher. Within minutes, that heating element was drawing 11 amps, right on the design specification for that unit. Another successful Samurai repair.
If your control board is beyond repair or failed in another manner, you can buy a replacement control board here.
Related posts:
- Dryer Takes Forever to Dry a Load of Clothes
- Bosch Dishwasher Diagnostic Procedures; dishwasher repair
- Mailbag: Dryer Blows Circuit Breaker on Heated-Dry Cycle Only
- Whirlpool-Built Dishwasher (includes KitchenAid and some Kenmores) Won’t Start, Clean LED Blinks Seven Times
- Fuzzy Crud on a Whirlpool-Kitchenaid-Kenmore Dishwasher Heating Element and Poor Heating/Drying
- Brand-Spankin’ New Bosch Dishwasher Not Drying Dishes
- Bosch SHU99 Dishwasher With a Mystery Leak Underneath, Somewhere on the Right-Hand Side, Making the Pump Run Constantly
- How to Replace the Water Inlet Valve in a Bosch Dishwasher
- Bosch Dishwasher Test Programs, Diagnostic Mode, and Error Codes
- Appliance Tip of the Day: Kenmore Dishwasher Front Panel Dead or Won’t Start or Quits Mid-Cycle
{ 4 comments… read them below or add one }
Thanks for your info on the bad soldier joint for Bosch dishwasher. Sure enough, I opened up the front and just as pictured. There must be a little too much amperage for this connection as I have seen other posts (not as detailed as yours, thank you!) that had the same description.
I have repaired the connection, and testing right now.
Thanks. Jazzer
When you come across this problem, the repair is generally not as simple as reflowing the solder at the joint.
I first went down the path of reflowing the solder joint on my personal dishwasher. That lasted about a month before failure again. Digging deeper, I found that the relay contacts are only rated for 10 Amps. Bosch themselves say the heater can be checked by measuring 11 amps on the wires leading from the relay to heater (or by measuring the DW current at the wall.).
Best solution is to replace the relay with a 12 amp rated version, which is what I did over a year ago. I have since repaired 2 additional boards, each having the same problem.
After dis-assembly of the relays, I found where the contacts were heavily oxidized, and the reeds holding the moving contact, plus the reed holding the fixed contact, were heat tarnished, proving that reflowing the solder may buy you some time, but there will be eventual failure.
Yours can be repaired at nominal cost. Contact me at BoschRepair at tx.rr.com for more information.
Great information. Two things regarding this Bosch DW repair: 1) For soldering novices, would you please provide some advice about materials and procedure for re-soldering a board like this and 2) If I do need to replace a control relay with a 12 amp, are these relays readily available at home supply stores, and how do you replace them? Thanks a ton. PF
For soldering help, see my post on working with electronic circuit boards:
http://fixitnow.com/wp/2007/12/03/working-with-electronic-circuit-boards-in-appliance-repair/
As for the relay, you can replace it if you like but there’s no need to. Simply re-soldering the burnt connection will fix it… assuming that was the problem to begin with. Even Bosch says this in their technical bulletins. I’ve repaired many this way and they’ve been running reliably.
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