Pilot will not kick on, TCO Switch is where?

no info generic answer --check thermocouple --and safety switches

Is the thermocouple secure, routed properly, no kinks, no sharp bends? Is the end of the unit properly aligned so the hottest part of the pilot flame is hitting the unit. Did you hold pilot switch in the light position for at least 30 seconds, before you set the gas valve to on? If all above OK, try this. Light the pilot using barbeque lighter once it lights keep the lighter on the t-couple for 30 seconds, then set the valve to ON and keep the lighter where it is. Once the main burner lights, remove the lighter. If the burner and pilot go off, your gas valve is bad.

Sounds like the TCO is tripping .../. because temperature inside burner is higher than 180°
Replace TCO ... and it problem is not fixed, replace gas control valve thermostat
http://waterheatertimer.org/troubleshoot-gas-water-heater-thermostat.html

If your light stays on after water is shut off, your flow switch is sticking. YOu need to replace the flow switch. If your light shuts off, but the unit continues to heat and trips your tco, then your element is bad and the unit needs replacing.

You can reset the code by turning Gage all the way up highest setting count to ten turn it to hot could to ten then turn to pilot count to ten and then turn it to desired temp burner should come on. Saves lots of money and time

If pilot stay lit, then thermocouple is working.
If pilot will light, then you have gas. If pilot goes out when pilot button is released, then thermocouple is next suspect.

Thermocouple tip must sit in pilot flame.
The pilot light heat applied to two different metals inside thermocouple causes small current.
The current travels back to gas control valve through copper line.
If the gas valve receive this current, then a magnetic switch stays open and allows gas into the gas control valve.
The magnetic switch is on the end of the red button you push down when lighting pilot. Essentially the red button is an override to the magnetic switch.
If the gas control valve does not receive the current, then the magnetic switch does not stay open when you release the red button.
When replacing thermocouple, note that it is not screwed very tight into the gas control valve. Finger tight + 1/4 turn. If it is overtightened, then the small thermocouple current shorts out against the gas control body.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Possibly the air intake located at bottom of heater needs to be cleaned with feather duster under water heater.
Read your product manual for steps.
Copy following link for general illustration.
http://waterheatertimer.org/images/State-select-air-intake-400.jpg
http://waterheatertimer.org/pdf/Flame-Arrestor-Screen-Cleaning.pdf
Other causes can be bad intellivent gas control valve, poor venting, hot attic, low gas pressure, dirty combustion parts, tripped FV system.
Copy following link for available intellivent troubleshoot resources:
The service manuals are large files and open slowly.
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

The pilot light jet may have got a little bit of dirt or grit in it which is preventing it from keeping alight. Try probing the jet with a fine piece of wire to see it the blockage can be dislodged. You may have to unscrew the jet to clear it by blowing air through it. Make sure gas is turned off first before removing any parts.

The pilot light also has a thermocouple that allows gas to the pilot light while the flame is burning. If flame goes out it shuts gas off to the pilot jet. The thermocouple is bypassed by a switch during the initial ignition and once the thermocouple warms up after a minute or two of holding in the bypass switch, it should maintain the pilot. If, after cleaning, the pilot light keeps going out, it would seem that your thermocouple is faulty and needs to be replaced

The T.C.O switch which is located on the outside of the burner area needs replacing. It has two wire that connect to it from the gas valve. This switch controls the gas to the pilot burner tube. If it has tripped it will not allow the
pilot to stay lit or allow gas into the pilot tube.

This can be caused by a number of problems.
1. How long has the pilot been lit before you turn it to burner? It needs to warm up the end of the coupler. When you push in on the knob to light the pilot, hold it in for a while after the pilot lights. This allows more gas/hotter pilot flame to warm things up.
2. How fast are you turning it to burner? You need to do it really slow. The gas is under pressure and can blow out the pilot if you do it too quick.
3. Is there a blockage in the tube? Lady bugs, spider webs, etc. can cause a blockage and this problem. It's pretty common. (A long pipe cleaner will clean it out in a few seconds.)
If all of these fail:
4. It it getting too much/too little air? Check the air gap in the end of the tube. (Also called air manifold)