Component Testing

THROTTLE POSITIONER DIAPHRAGMS:

1. Disconnect all the vacuum hoses from the TP and mark them for correct reinstallation. Fig. 33

Fig. 33 Testing TP Diaphragms:

2. Using a handheld vacuum pump, check both diaphragms by applying 15 - 18 in.Hg of vacuum.
3. If the diaphragms leak or the TP linkage does not retract, replace the TP.
4. Remove the vacuum pump and reconnect both vacuum hoses.

VACUUM JET:

1. Remove Jet from vacuum line between intake manifold and the TP.

Fig. 34 Testing TP Vacuum Jet:

2. Blow air through each side of Jet and check for blockage. Fig. 34
3. If a problem is found, replace Jet.

VACUUM SWITCHING VALVE (VSV):

1. Disconnect wire connections and vacuum hoses from the VSV. Remove VSV from the engine.

Fig. 28 Testing VSV With Current Applied:

2. Connect service wires from the VSV terminals to the battery. Fig. 28
3. Blow air into either pipe and check that air passes freely, (valve open).
4. Disconnect service wires from battery and blow air into either pipe.
5. Air should NOT pass, (valve closed).
6. If a problem is found, replace vacuum switching valve.

Fig. 30 Testing VSV For Short Circuit:

7. Using an ohmmeter, check the resistance between the terminals and the VSV housing. Fig. 30
8. If there is any continuity, replace the VSV.
9. Measure the resistance between the terminals of the VSV. Fig. 31

Fig. 31 Testing VSV For Open Circuit:

10. The resistance should be 38 - 44 Ohms at 68°F ambient temperature.
11. If resistance is not within specifications, replace VSV.
12. Reinstall VSV on the engine. Reconnect vacuum hoses and electrical connections.

VACUUM TRANSMITTING VALVE (VTV):

1. Remove the vacuum transmitting valve (VTV) from the vacuum line.

Fig. 65 Testing Vacuum Transmitting Valve:

2. Air should blow from B (Black) to A (Gray) without resistance. Fig. 65
3. Air should NOT flow from A to B.
4. If a problem is found, replace the VTV.
5. Reinstall the VTV in its vacuum line.