Handbook 652 Body Electrical Diagnosis Solid State Relays Solid state relays are actually transistors– miniaturized electronic components that have a purpose similar to mechanical relays. Transistors, like relays, allow a circuit with low current to control a circuit with high current. It is important to know how solid state relays operate in order to troubleshoot them. • The power source (B+) and power out are shown as 3 connectors in a row. The middle connector has a diode installed to prevent current surges. • The single connection on the top energizes the solid state relay when it is grounded.
You have to look at the system circuit diagram and consult the system outline in the EWD or Repair Manual to determine proper operation for each solid state relay application. 64 Technical Training