I see several challenges to the concept.

I think it will be difficult to get dealers to pay for hotline access or use
because automakers do not charge their dealerships to access the automaker's
hotline.  In other words, why pay for third party help if they can get it
straight from the factory for free?

The information available to third party hotlines cannot be as current as
the information available to automakers' technical service departments.

I saw from your web site that you are looking for experienced, certified
technicians, which most dealerships already employ.  If you are going to
sell advice to dealerships, the person providing the expertise has to be
even higher than a certified tech, i.e. baccalaureate, masters, or higher
degree in automotive technology.

the people who are best at that job will go work for an automaker unless you
offer comparable or better pay and benefits, i.e, new company car every
year, low cost employee leases for spouse and family, new and used car
purchase plan, full health insurance for family, life insurance, 401k,
education reimbursement, dental and vision plans, etc.