Whirlpool gold series WDF750SAYM0 dishwasher starting issue

My Whirlpool gold series WDF750SAYM0 dishwasher has developed a strange problem. I have this problem for over 6 months now. After I start it, within a few seconds the Start and Washing lights start blinking. ⏎

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The way I have resolved it is that when the lights start blinking I hit Cancel which causes the dishwasher to drain. When the Cancel completes all lights go off. Then, I try to start again, and get the blinking again. I hit Cancel etc. This loop of attempts repeats and the dishwasher seems to get further into the washing cycle before lights blink again. Eventually, the dishwasher starts. This entire process takes about 30 minutes sometimes. ⏎

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The problem is worse on cold days, i.e. I have to do a lot more of these repeats, and it can take up to 1 hour for the dishwasher to run. This makes me suspect the heating element because I feel the water is taking longer to get hot, but I'm not sure. On extremely cold days, the dishwasher, will just blink lights erratically and not even start, i.e. it won't do the sequence I described above until I do a diagnostic reset. Then, it's back to the above sequence to start the dishwasher. The diagnostic reset is showing me 9 flashes pause and then 1 flash. i.e. 91⏎

I have pulled the dishwasher out, there are no leaks underneath, no water collecting inside, the drain hose is not kinked and the garbage disposal knock out was already done prior. ⏎

I cant find a service manual for the WDF750SAYM0 model so shooting in the dark right now based on codes found on the internet. From what I have found, the possible issues for code 91 are ranging from: drain pump, diverter motor or harness, or possibly a control board issue. ⏎

If you have a link to the service manual or any thoughts on the issue, I'd appreciate it. Thank you very much.