Vacuum Modulator Diagnosis

1. Disconnect vacuum hose and rotate modulator until port faces downward. If any liquid, such as transaxle fluid, water or gasoline, drains out, modulator should be replaced.

2. Connect suitable gauge to modulator vacuum line. If gauge reading is less than 13-17 inches Hg with engine at normal operating temperature and transaxle in drive, check vacuum system and correct as needed.

3. If sufficient vacuum is present, remove modulator and apply 15-20 inches Hg vacuum to modulator port.

4. Modulator plunger should be drawn in as vacuum is applied, and vacuum should not bleed down for at least 30 seconds.

5. Remove modulator and roll on flat surface. If sleeve is not concentric with body of, modulator should be replaced.

6. Ensure modulator plunger valve moves freely, without binding or sticking.




7. Install modulator along with "known good" unit in tester J-24466 or equivalent.

8. Holding assembly level, press two modulators toward center of tool while observing gauge line.

9. If gauge line remains blue, modulator is defective. If line is white, modulator is satisfactory.

10. Modulator should be replaced if it fails to perform as outlined.

11. If modulator and vacuum system are satisfactory, perform "Oil Pressure check" as outlined and refer to "Troubleshooting" section.