Since the timer is the "brains" of a washing machine, every time the machine doesn't do something it should be doing, the timer is always a possible suspect. Generally, they're pretty reliable, tho.
The start up sequence for a Maytag washer is as follows:
1. If the lid is closed, power goes through the air pressure switch and the temperature selection switch to the water mixing valve to fill the wash basket with hot, warm or cold water.
2. As the wash basket fills, air is trapped in a vertical tube that goes to the air pressure switch behind the console on the top of the machine. Once the air pressure in that vertical tube reaches a factory preset level (indicating that the washer is full), the air pressure switch diverts power from the water mixing valve to the timer motor.
3. The timer motor then rotates the timer which coordinates the wash cycle.
If your machine stops after filling with water, and just sits there and does nothing, it could be that the air pressure switch isn't working properly and the timer motor isn't getting power. Check to see that the timer motor only gets 110 VAC power after the washer stops filling. If that's the case, then the air pressure switch is OK.
If the timer motor is getting power, but it's not turning, then the normal fix is to replace the whole timer with a rebuilt timer.
Each of the electrical connection tabs on the timer will have a number beside it. Just write down the colour(s) of the wires going to each tab on the old timer so that you can connect the wires to the correct tabs on the new timer.