LG 8072ST Doesn't drain but not clogged

I’m about to throw this %#*@ thing out in the yard and run over it with a bulldozer…the OE light keeps coming on during cycle and shutting the dishwasher down. It will drain manually. I have taken the drain pipe off at the garbage disposal and cleaned both the pipe and the inlet to the garbage disposal. I ran a rinse cycle with the hose disconnected from the garbage disposal and it ran the full cycle and drained with really good flow. I plugged the drain pipe back in to the garbage disposal, ran another rinse cycle and it completed the cycle normally and again drained with good flow. No OE error light on either rinse cycle. Ran a QUICK cycle and the %#*@ thing throws the OE error light and shuts down. Any ideas why? Is there a sensor somewhere I am missiing? I cleaned what appeared to be a sensor in the drainage filter cup. Why will it drain normally manually and in the rinse cycle but not in a normal or QUICK wash cycle?