Why do ABS light and traction control light illuminate intermittently?

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For 2 years both lights come on randomly. First time at dealership added air to tires & lights went off. Lived with intermittent illumination until last month at dealership for brake recall work & asked them to check these lights. Dealership found fuse 21 open & replaced. 2 weeks later the 2 lights came on again while driving as well as message Service ABS system. Went several days no lights. The next time the lights illuminated when starting car, took to independent shop. He pulled codes C0020-16 ABS pump motor control circuit voltage below threshold, C0020-1C ABS pump motor control circuit voltage out of range, U0420 invalid data from power steering control module. He recommended replacing ABS module. Would a faulty ABS module cause fuse 21 to blow? It sounds more like a short in a wire to me. Any suggestions on what to check?