Very slow on/off of check engine light when car driven through heavy rain. on 1990 Toyota Camry

1990 Toyota Camry check engine light came on only when driven through a very heavy rain storm with high water on the road. Light came on and off again in a systematic measured slow frequency and there were many seconds between. No noticeable performance changes. Pulled off road until rain abated. Then drove again, on/off continued for several blocks then stopped completely. Can this happen just from excessive water splashing up on engine area????

Asked by for the 1990 Toyota Camry