5000CD Quattro Sedan (Canada) L5-2226cc 2.22L SOHC Turbo (MC) (1988)
Thermo Time Switch: Description and Operation
Fig. 9 Thermo Time Switch
When the engine coolant is below the switch calibration temperature, the thermo time switch is closed completing the cold start valve ground circuit.
During cranking battery voltage is applied to both the cold start valve and timing switch, and the start valve injects fuel into the manifold. After 3 - 10
seconds, voltage applied to the thermo time switch heats an internal element which expands opening the cold start valve ground circuit and the cold start
valve is de-energized. When coolant temperature exceeds the switch calibration temperature, the switch remains open and the cold start valve does not
operate.