Quantum Syncro AWD L5-2226cc 2.22L SOHC (1987)
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connect engine tester VW 1367 to test connector
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push % button on VW 1367
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check duty cycle
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28 +/- 2% (with oxygen sensor connected)
If NO
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adjust duty cycle by turning idle screw
If still NOT OK, and duty cycle reading is 33% or 40%
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recheck that A/C is switched OFF
If A/C OFF
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check idle switch for function or for open circuit between idle switch and control unit connector. See wiring diagram
If cycle reading fluctuates irregularly between 25% and 20%
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check for open RPM signal circuit from electronic ignition control unit to CIS-E control unit
If duty cycle reading is 25%
^
idle speed incorrect
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check for leaks at throttle body gaskets, seals and all hoses for intake system
If NO leaks present
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check for open circuit between idle stabilizer valve and CIS-E control unit
A/C switch signal, checking
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switch A/C ON
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RPM boost approximately 100 RPM
If NO
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disconnect harness connector from CIS-E control unit
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check for open circuit between A/C switch on dash and CIS-E control unit connector terminals 6 and 16
A/C compressor signal, checking
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switch A/C ON
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open throttle enough to open idle switch
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duty cycle 40% with A/C compressor engaged and idle switch opened
If idle speed exceeds 1000 RPM with A/C compressor OFF
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voltage signal wire from compressor to control unit connector terminal 19 interchanged with terminal 16.