Volkswagen Golf/Jetta 2 manual

Cold start valve and thermotime switch - testing
Fuel and exhaust systems - K-Jetronic fuel injection - 8 valve engines / Cold start valve and thermotime switch - testing


Cold start valve
1 The thermotime switch energises the cold start valve for a short time on starting. The time for which the valve is switched on depends upon the engine temperature.

2 This check must only be carried out when the coolant temperature is below 30°C.

3 Pull the connector off the cold start valve and connect a test lamp across the contacts of the connector (see illustration).

9.3 Cold start valve test lamp connections
9.3 Cold start valve test lamp connections

4 Pull the high tension lead off the centre of the distributor and connect the lead to earth.

5 Pull the connector from the thermotime switch then connect an extension lead from earth to the thermotime switch W terminal (green/white wire). The red/black wire must not be earthed.

6 Operate the starter and check that the test lamp lights up. If it does not, then there is an open circuit which must be located and repaired.

7 To check the cold start valve, leave the thermotime switch W terminal earthed, remove the cold start valve and re-attach its connector. Take care not to break the gasket when withdrawing the cold start valve from the inlet manifold.

8 With fuel line and electrical connections connected to the valve, hold the valve over a glass jar and operate the starter for 10 seconds. The cold start valve should produce an even cone of spray during the time the thermotime switch is on.

9 Wipe dry the cold start valve nozzle with a clean non-fluffy cloth, then check that the valve does not drip or its body become damp over a period of one minute. If proved defective, renew the valve.

Thermotime switch
10 To check the thermotime switch, proceed as described in paragraphs 3 and 4 inclusive.

The coolant should be at 30°C. If the switch needs to be cooled down to the temperature specified, remove it and immerse its base in cold water. When cooled, earth the switch to make the test.

11 Operate the starter for 10 seconds. The test lamp should light immediately and stay on for three seconds.

12 Refit the high tension lead onto the distributor and reconnect the lead to the cold start valve.


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