I recommend the Upgraded Circuit Protected Tail Light Converter Hardwire Kit with 4-Pole Connector # 119178KIT. The # 119178KIT is a better value than the # C59236. They both have a powered converter which helps reduce the wear and tear on the wires to ensure they keep working longer and connects directly to your Scion iQ's wiring with the included quick-splice connectors.
To determine where to splice into your Scion iQ's tail light wiring, you will need to consult the included instructions.... view full answer...