Z31 Computer Pin Out
The Z31 came with four different Crank pulleys. Non turbo from 84 to 86 had all V-belts. The turbo models used a ribbed belt for the alternator and v belts for the other accessories. Early 1987 models switched to to all ribbed micro v belts. The later models 4/87-89 used a longer snout on the crank shaft, therefore using a new pulley that is a 13.6 mm thicker.
ECCS Location
The ECCS or Computer for the Z31 is located behind the passenger's kick panel. This is the small panel on the outer wall right below the glovebox. You will need to remove 2 screws to get the panel off.
There are three connectors that plug into the ECCM. These connections can sometimes corrode and cause Driveability issues. Cleaning these will resolve some problems but sometimes for Diagnostic procedures you will need to check the pinout on sensors. The diagram below will show you what each pin connects to.