Here are you parts includes a wiring diagram
Parts for Maytag MDET236AYW Dryer - AppliancePartsPros.com

I am not sure I understand the problem.

Does the timer not advance in both timed dry and auto cycles?
Since you mentioned the heater is that also not working?

Have you checked the power?
If not I would start there.
Try flipping the breaker off/on slowly a couple times. Sometimes you can loose half the line without actually tripping the breaker.
Check the voltage at the plug
L1 to L2 should be 240 volts
L1 to Neutral and L2 to Neutral, both should be 120 volts.
If OK
Unplug the unit and check the wires at the terminal strip in the machine to make sure none are loose or burned out
If OK
Check the power at the terminal strip.
Do this with the heater off and on.
[COLOR="Red"]Be careful as 240 volts is lethal !!![/COLOR]

[COLOR="Blue"]I believe that it doesn't make a difference what cycle its on , the timer stays wherever you set it.[/COLOR]
Double check this.
The reason is that the timer motor circuit path is different for timed and auto.
Timed dry is fairly direct.
Auto goes through the normally open contacts on the cycling thermostat.

I would start by checking the cycling thermostat.

This is a 5 connector thermostat.
The inner two connectors are the thermostat's internal heater so you do not have to worry about these.

The outer three are a common (C) (Blue wire), a normally closed (NC) (purple) and a normally open (NO) (orange).

At room temperature the C to NC should be closed (0 ohms) and the C to NO should be open (infinite ohms).

Now you will have to heat up the face of the thermostat so it switches over. You can usually hear this. I use my soldering gun but you could also heat it up on a stove element. When it switches the the NC will open and the NO will close.

I do not know if the connectors are actually marked so if you have to remove the thermostat from the unit be sure to make yourself a drawing of where the wires go.
From the picture of the thermostat I cannot make out at what temperature it should switch over but they are usually around 150 degrees F.

If the label is on yours and shows something like L150-25. Then the thermostat opens at 150 degrees F and re-closes at 125 degrees F.

OK not great news as I was hoping it would be that thermostat.
I am assuming that you actually measure Common to Normally Open when you heard it switch over.

I cannot find a timing chart for this unit so have to do a bit of guessing.

Unplug the unit and set it to a mid scale auto mode (where the timer does not advance.
Measure from the side of the timer motor which has the black and orange wires attached to the orange connection at the cycling thermostat. It should be 0 ohms.

I do also have the wiring diagram I can email or attach if there is a way if it would help.