EGR Coolant Temperature Override (CTO) Vacuum Switch

Drain cooling system. Disconnect vacuum hoses from EGR CTO switch. Remove switch from vehicle. Cool switch to lower specification. See EGR CTO OPERATING TEMPERATURES  table. Blow through one fitting of switch. Air should not pass through switch. Heat switch to upper specification. See EGR CTO OPERATING TEMPERATURES  table. Blow through switch. Air should pass through switch. If switch does not function as described, replace switch.