Non Turbo

Fig. 1 Warm up enrichment current graph:

Fig. 7 Differential Pressure Regulator Test Setup:

When the starter is activated, the current to the differential pressure regulator is increased to enrich the fuel mixture, Fig. 1.. The enrichment supplements the operation of the cold start valve if the engine is cold. The amount of starting enrichment is dependant on the engine coolant temperature. Regulator current can briefly go to its maximum value if the engine is cold (maximum starting enrichment time is 1.5 seconds). To test the system:
1. Connect differential pressure regulator test harness (VW 1315A/1), Fig. 7, between the harness plug and the differential pressure regulator and hook up a multi-meter set for 0-200 mA.
2. Insert connector (0 ohm) end of adapter VW 1490 into coolant temperature sensor harness plug to short the terminals together.
3. Observe multi-meter while cranking engine for about 3 seconds.
4. Current should be greater than 70 mA for the first 1.5 seconds of starter operation.
5. If current is not as specified;
a. Check for open circuit in wire between terminals 24 on control unit plug, and 15a on starter.
b. Check between control unit plug terminals 21 (coolant temp sender) and 2 (ground). Resistance should be:
Approx. 2.5K ohms @ approx. 20°C (68°F)
Above 2.5K ohms @ coolant temp. below 20°C (68°F)
Below 2.5K ohms @ coolant temp. above 20°C (68°F)
c. If the wiring is OK, replace the control unit.