The electronic control module on a 1999 Chevy S-10 is the computer responsible for all engine management duties. This includes the ignition, fuel injection and emission control. The computer is very sensitive to voltage spikes due to short circuits, poor grounds or sparking the battery terminals. Accidental reverse polarity can severely damage the unit. The ECM on a 1999 S-10 is located under the dash on the driver's side of the truck.
Lift the hood and disconnect the negative battery terminal using a wrench. Move the terminal away from the battery to prevent it accidentally touching the battery terminal. Allow 20 minutes for the static electricity to dissipate before beginning.
Remove the nuts on both sides of the computer bracket using a 10 mm socket. Pull the computer out of its support bracket. Pull all three electrical plugs out of the computer. Remove the computer.
Remove the cover from the top rear of the computer using a socket. Do the same to the new computer. Release the two clips on the sides of the computer prom (memory chip) that is directly under the cover. Very carefully pull the prom up a small amount on one side and then lift it straight up out of the computer.
Ground yourself against the vehicle to dissipate any static electricity that could potentially damage the computer. Install the prom into the new computer, making absolutely sure that it is inserted properly so the terminals are not bent in the process. Raise the side clips and snap them in place on the prom.
Install the top cover. Push the three electrical plugs into the computer. Install the new computer and tighten the two nuts securing it to the bracket. Install the negative battery terminal on the battery and tighten with a wrench.
