Get a Haynes or Chilton's manual for your truck. They are detailed enough for what you want.
Look at the lower rear end of engine
There are several relay switch is on your 1996 GMC Jimmy. The brake light relay switch can be found below the dashboard in the engine compartment.
get a new engine
A blinking engine light could mean several things. The only way to know for sure is to have the Jimmy checked out by a licensed mechanic.
It would depend on the year and engine size. A 1995 Jimmy with the 4.3L made 200hp. In 1996, it made 195.
KEY ON ENGINE OFF.... 60-66 PSI
Must remove the entire engine
The knock sensor on the 1996 GMC Jimmy 4-wheel drive, 4.3 liter 6-cylinder is mounted in the engine block. Under the hood, look in the lower engine area on the passenger side, beneath the cylinder head.
Just remove pan and change bearings.
Removing the seat back from the pan on a 1996 Jimmy won't cause much trouble, and can be easily done without creating problems with the reclining mechanism.
You have to remove the engine first from the car. Place it on an engine stand and work your way on removing the cranksaft. No way to remove it while the engine is in the car.
unhook the battery for abt. 30 sec and re connect