Starting Enrichment

Fig. 7 Differential Pressure Regulator Test Setup:

1. Connect differential pressure regulator test harness (VW 1315A/1),Fig. 7, and hook up a multi-meter set for 0-200 mA.
2. Insert connector (0 ohm) end of adapter VW 1490 into open connector of coolant temperature sensor plug.
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.