It is electric.
Buy the manual. If you have never attempted this before and can't do it by reading the manual, then don't try it. It's not worth screwing up and killing someone.
Metro Atlalilco was created in 1994.
Metro Obrera was created in 1994.
Metro Coyuya was created in 1994.
Metro Apatlaco was created in 1994.
Metro Aculco was created in 1994.
Metro Garibaldi was created in 1994.
Metro UAM-I was created in 1994.
Metro Doctores was created in 1994.
Metro Iztacalco was created in 1994.
Metro Iztapalapa was created in 1994.
I have often found my 1994 Haynes Repair Manual's electrical section to be helpful.