To find it, you should:
1. Consult your owner's manual: This is the best resource. It will show you a diagram of the fuse box and identify the flasher relay.
2. Locate the fuse box (both under the dash and under the hood if there are two): Open the fuse box cover carefully.
3. Look for a relay that's labeled or is visibly identifiable as the flasher relay: It may be labeled "turn signal," "hazard," or have a symbol of a flashing light. Relays are usually small square or rectangular components with multiple pins. They're often grouped with other relays.
4. If unsure, visually inspect the relays: Sometimes, if you have a spare relay, you can compare its size and pin configuration to the relays inside the fuse box. Be very careful not to switch relays you are not sure of.
If you can't find it using these steps, you might need to consult a Toyota Hiace repair manual specific to your year and model, or seek the help of a qualified mechanic. Remember to disconnect your car's negative battery terminal before starting any work on the electrical system.