I have a kenmore elite 665.16919 that displays a double dash when I push the start button. any ideas why it won't start?

SOURCE: Kenmore Elite Dishwasher model 665.16983. Start

If you already tried the cycle as I did without success

you can try

SOURCE: I have a kenmore elite dishwasher that stop

The most likely failure that causes this would be the thermal fuse that is located in the console.

It is a temperature controlled device that can trip if there is a lot of heat in the control area.

If you want to tackle the repair it is not too difficult and requires a basic understanding of electricity and an ohmmeter.

I would need your model number that is on the tag just inside the door to give you detailed instructions but basically the fuse is attached to the control board just behind the button panel. The fuse does not look like a regular fuse and it has 2 wires going to it.

SOURCE: We have a Kenmore Elite 665.15953; the display

The blinking "clean light" is a common problem with some of the Kenmore and Whirlpool models dishwashers.
The problem is usually attributed to water supply temperatures being too low when filling.

Apparently, there are some issues with the temperature sensing circuits in some dishwashers that causes an error code to be generated if a certain water temperature is not achieved in a specified time interval (this time may differ between models).
There is a reset sequence that you can try to clear the fault.
Push the NORMAL WASH then HEATED DRY buttons in that sequence two to three times.
The unit will enter diagnostics mode, but can be stopped by pressing the CANCEL button.
This will clear any existing faults and should return the dishwasher to normal operation.

To keep the fault from returning, it is recommended that you run your hot water faucet in the kitchen until it runs hot BEFORE you start the dishwasher.
This will heat the water in the supply line for the dishwasher (most dishwashers are fed from the kitchen sink supply line).

The theory is that if you fill the dishwasher with hot water from the start of the wash cycle instead of the cool water that is normally in the lines (especially if you have a hot water tank located far away from the kitchen), this should satisfy the requirements of the temperature sensing circuits.
If the fault reappears, there should be a tech sheet located inside the lower panel under the door that explains what the fault is.
The flashing light will be a series of flashes, followed by a pause.
If you indeed have a component problem, it will depend on the number of flashing lights in the sequence.
Refer to the tech sheet to determine WHAT component is affected and how to troubleshoot.

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SOURCE: Whenever I press the start

You can get the control board on the link below. it cost $77.36.
http://www.appliancepartspros.com/Appliance-Parts/frigidaire-control-item-number-ap4499594.aspx

As for instaling it your self you will need to get a service manual. To get one on the link above click on the live chat on the left of the picture and ask for one.