Thermo Time Switch (Except Vanagon)
- Engine temperature must be below 86°F (30°C). Disconnect cold start valve wiring harness connector and attach LED test light to terminals. Have assistant hold ignition switch in the "START" position while observing test light.
- Light should stay on for 3-8 seconds depending on coolant temperature. If light does not come on, check voltage supply to cold start valve and repair as necessary. If voltage to valve is okay, check ground circuit through thermo time switch. Replace thermo time switch if contact to ground cannot be made.