I'm repairing a control board for a premium washing machine (model #s at bottom for anyone that's interested). The machine was displaying an error code for relay failure. I took the board out of circuit, injected voltage on the DC bus, and detected two shorted 1N4148 "T4" diodes, each in parallel to a 12v SPST-NO relay (marked with arrows below). I replaced them. Each relay switches one side of the water heating element (+ or -). I have not tested the repair yet, but the machine does work without issue with a substitute board.
Trying to figure out what may have caused the diodes to short?
Relays: Omron 12V G2RL-1A-E
Control Board: W10406607 / W10406604 (alternates, W10342325 / W10342327, W10388205, W10427972, W10384506, W10354088, W10406635)
I found these short diodes using isopropyl alcohol (99%) and a microscope (loupe or optivisor works for less $$). Here's a video from my microscope camera showing the alcohol
This is one of the larger "neighboring" diodes, MURS160T3G "U1J" in SMB package. Same relay, so perhaps a strange bit of design here.