[COLOR="Blue"]How do I check Timer assembly and timer motor for continuity? Which Leads?[/COLOR]
Remove one wire going to the timer motor and measure across the motor winding with a meter.

[COLOR="Blue"]Can I rig Dryer to temporarily run without timed auto shut off to test timer?[/COLOR]
You do not have to do that as the timer is connected directly across the line (L1 to L2) when in timed dry mode.

Not sure what other things you want to check.

If timer advances in timed dry but not in auto, then odds are it is not a timer problem.
What is wrong with the machine, symptoms etc. ??

Here are your parts
Replacement parts for WHIRLPOOL TEDS840JQ2 | AppliancePartsPros.com

Here is the wiring diagram
http://www.servicematters.com/docs/wiring/Wiring%20Sheet%20-%208528190.pdf

Be sure to check the 120 sides of the power as the motor runs on the Neutral to L1 leg. If you have an interior light and it is working then you have Neutral to L1 voltage.
Try flipping the breaker off/on slowly a couple times, sometimes you can loose half the line without actually tripping the breaker.
If this does nothing, 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.
Be careful as 240 volts is lethal !!!

Other things can be checked with the unit unplugged using ohms which is safer. Be sure to unplug at least one side of any device you are measuring. This prevents you from reading an alternate/parallel circuit path.

At the top of the list would be the motor's thermal fuse. This is the one on the blower. If it is blown be sure to check/clean your vent system as that is the most common cause of it blowing.

Then you have the door switch and the push-to-start relay contacts.

Then the contacts in the timer. Set the timer to mid-cycle timed dry to check these.