The security system is going off in my toyota tundra 2001 truck

remove remote start and clear the no start problem first.

https://www.justanswer.com/toyota/5do8v-toyota-tundra-sr5-2000-tundra-changed-battery.html

Question edited for clarity.
Question moved to model category.

2006 Toyota tundra 4.7L Front End Torque Specs

toyota-specs.com https://toyota-specs.com > cars > 2006 > tundra4.7 > t...
Toyota Tundra Front Axle Nut Torque Spec : 203 ft-lbs · Toyota Tundra Wheel Hub Torque Spec : 100 ft-lbs ...

BHA53102 Axle / Spindle Nut Torque Specification

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https://www.autozone.com/diy/repair-guides/toyota-tundra-2001-06-firing-orders-repair-guide-p-0996b43f80378dce

To reset it lock and unlock the drivers door with the key.

Toyota Tundra Maintenance & Repair Questions - CarGurus

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Toyota Tundra Questions - CarGurus

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CarGurusGet fast answers to your Toyota Tundra questions from experts in the CarGurus automotive ... My 2000 tundrasr5 4.7l 4x4 wont start! Thought wasn't getting fuel because tries to turn over but wont. ... Tundra Dead Battery, How Do I Open The Door Or Hood To Recharge? ... 4wd Hi Light Flashing, But Will Not Engage.

the IMMO light on,,,, the IMMOBILIZER, ever read the operators guide

Can not start car, that is because the security system is in ALARM
and that tells the IMMO not to allow starting, all by design.

the alarm system must be diagnosed,
the manual will show how the alarm is detecting a breach.
all cars, have tests to see what is in alarm.
look here.
alldata.com
see the security system checks.

The security system on Toyota products are added by the distributor in your region. Many of those security systems will not allow more than 4 key fobs to be programmed into them. Have you owned this vehicle since it was new? Have you tried to program more that 4 key fobs into it? Have you tried programming it more than 2 times? If you security system has had more than 4 key fobs programmed in then the only way to get it to reprogram is the replace the security unit with a new one. I found this out the hard way and had to replace mine in my 2000 tundra.

the linkage is probably binding.disconnect the linkage at the transmission and see if it moves properly.

most likley you have a bad starter next time it happens try tapping on starter when your son holds the key in the start position