If you do not have your own business and the truck is a vehicle you personally own, then you cannot include the truck as an asset. If you use the truck while doing work for your employer, you can deduct the business mileage driven in the job-related expenses section of TurboTax.
Note that job-related expenses are included as itemized expenses and only the amount that exceeds 2% of your adjusted gross income are deductible when itemizing.
Here is more information on deducting mileage and entering job-related expenses in TurboTax:
https://ttlc.intuit.com/replies/3300445
https://ttlc.intuit.com/replies/4800418