Its easy to replace solar sensor on Toyota Sequoia.
DTC 21 code will be seen in car scanning.This code indicates solar sensor replacement.
You need to ohm out the wires between the solar sensor and the control head, if the wires are good, replace the solar sensor.
The sensor is located on the drivers side dash, near the windshield.To replace solar sensor you pry up on it with a screwdriver and it pops out, then just disconnect it and replace.

The car will not start?
Car will not crank?
Car has no spark?
How to troubleshoot car battery?
How to test starter solenoid?
http://schematicsdiagram.blogspot.com/2011/06/how-to-test-starter-solenoid.html
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How to test cars starter?
http://schematicsdiagram.blogspot.com/2011/06/how-to-test-cars-starter.html
How to replace starter in car?
car will turn over but will not start?
Car wont start?
DTC 21 code will be seen in car scanning.This code indicates solar sensor replacement.
You need to ohm out the wires between the solar sensor and the control head, if the wires are good, replace the solar sensor.
The sensor is located on the drivers side dash, near the windshield.To replace solar sensor you pry up on it with a screwdriver and it pops out, then just disconnect it and replace.
See the image below of solar sensor:---
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For more car related problem troubleshooting:---
This are the sections, you can go through and click the link to read its troubleshooting.
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The car will not start?
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Car will not crank?
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Car has no spark?
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How to troubleshoot car battery?
-----------------
How to test starter solenoid?
http://schematicsdiagram.blogspot.com/2011/06/how-to-test-starter-solenoid.html
--------------------
How to test cars starter?
http://schematicsdiagram.blogspot.com/2011/06/how-to-test-cars-starter.html
How to replace starter in car?
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car will turn over but will not start?
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