On the right side of the firewall in the engine compartment there is a plastic cover that is over the A/C blower and the fuel pump relay. Pull this cover and the tan wire with a black stripe is in there. Set timing normally from there.
Your 1999 Chevy blazer doesn't have a timing belt.
It has a timing chain.
Chain
no
There is no timing adjustment, The computer controlls the timing.
timing chain
It has a Timing Chain.
It does not have a timing belt, it has a chain.
how to change timing cover gasket on a 1996 chevy lumina
belt
Belt
Possible but probably not.