Idle Stabilizer - Checking/Adjusting Procedures
87VW04Applies To Quantum
w/5-cylinder
1984-1987
Group
25
Subject
Idle Stabilizer
Part Identifier 2558
Key Points
Checking/adjusting procedures
H
Number
87-06
October 12, 1987
Note
The following pages contain Repair Manual information which will be integrated into the Quantum Repair Manual at the time of the next update.
Idle stabilization, model year 1984 only
Requirements
^ Engine cold
^ A/C switched OFF
^ All other electrical consumers switched OFF
- attach multimeter US 1119, using VW 1315A/2 adaptor to idle stabilization valve, switch to 2A scale
- switch ON ignition
^ 945-1055 mA
If NO
- replace control unit
- start engine and warm up to 80~C (176~F) oil temperature, with A/C switched OFF
^ idle stabilizer mA value should be:
430 +/- 20 mA
If NO
- adjust throttle by-pass screw (arrow) until 430 +/- 20 mA is obtained
- check idle speed
^ 800 +/- 70 RPM
CAUTION
Part numbers are for reference only. Consult your Parts Department for the latest information.
Thermoswitch, checking
- disconnect thermoswitch harness connector and attach multimeter US 1119 to thermoswitch
^ below 30~C (86~F) = 0 Ohms (continuity) above 40~C (104~F) = Ohms (open)
If NO
- replace thermoswitch
(Part Number: 035 919 369B)
Idle stabilization valve, checking
Requirement
^ Engine oil temperature approximately 50~C (122~F)
- switch ON ignition
^ idle stabilizer valve must hum and vibrate
If NO
- disconnect idle stabilizer valve harness connector
- attach multimeter US 1119 to harness connector set meter to DC volts
- switch ON ignition
^ approximately battery voltage
If YES
- replace idle stabilizer valve
If NO
- go to next step
- connect multimeter US 1119 between terminal 14 of relay socket 11 and terminal 5 of relay socket 12 on fuse/relay panel
- switch ON ignition
^ approximately battery voltage
- switch OFF ignition
- turn air conditioner ON
- connect multimeter US 1119 between terminal 2 of relay socket 12 on relay panel and ground
- switch ON ignition
^ approximately battery voltage
- switch OFF ignition
Note
The middle cavity of the idle stabilizer valve harness connector is NOT occupied (84 only).
- connect multimeter US 1119 between terminal 11 of relay socket 11 and idle stabilizer valve harness connector
^ 0.0 ohms (continuity)
- connect multimeter US 1119 between terminal 4 of relay socket 12 and idle stabilizer valve harness connector
^ 0.0 ohms (continuity)
- disconnect throttle switch harness connector
- connect multimeter US 1119 between harness connector and ground, set meter to DC volts
- switch ON ignition
^ approximately battery voltage
- switch OFF ignition
- connect multimeter US 1119 to both terminals of throttle switch harness connector, set meter to ohms scale
^ throttle in idle position = 0.0 ohms (continuity) throttle slightly open = infinity ohms (open)
- connect multimeter US 1119 between terminal 13 of relay socket 11 and thermoswitch wire (brown/ black)
^ 0.0 ohms (continuity)
If resistance OK but idle stabilization NOT OK (engine speed varies):
- replace control unit
Note
Quantums, model year 1984, use a separate control unit for the idle stabilizer valve. Part numbers:
^ Automatic transmission 443 907 393 K
^ Manual transmission 443 907 393 J
CAUTION
Part numbers are for reference only. Consult your Parts Department for the latest information.
Idle stabilization, model years 1985-1987
Requirements
^ Engine oil temperature minimum 80~C (176~F)
^ Ignition timing OK
^ A/C switched OFF
- connect engine tester VW 1367 to test connector
- push % button on VW 1367
- check duty cycle
^ 28 +/- 2% (with oxygen sensor connected)
If NO
- adjust duty cycle by turning idle screw
If still NOT OK, and duty cycle reading is 33% or 40%
- recheck that A/C is switched OFF
If A/C OFF
- 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%
- 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
- check for leaks at throttle body gaskets, seals and all hoses for intake system
If NO leaks present
- check for open circuit between idle stabilizer valve and CIS-E control unit
A/C switch signal, checking
- switch A/C ON
^ RPM boost approximately 100 RPM
If NO
- disconnect harness connector from CIS-E control unit
- 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
- switch A/C ON
- open throttle enough to open idle switch
^ duty cycle 40% with A/C compressor engaged and idle switch opened
If idle speed exceeds 1000 RPM with A/C compressor OFF
- voltage signal wire from compressor to control unit connector terminal 19 interchanged with terminal 16.
If circuit OK
- replace CIS-E control unit
Idle stabilizer valve, checking
Continuity, checking
Control unit connector
Test connection
- connect multimeter US 1119 between the test connection (arrow) and terminal 15 of the disconnected CIS-E control unit connector, switch meter to ohms scale
^ with idle stabilizer valve disconnected:
zero ohms (continuity)
- connect multimeter US 1119 to terminal 2 of the stabilizer valve harness connector and terminal 3 of the disconnected CIS-E control unit connector
^ zero ohms (continuity)
If NO
- check for open circuit, using wiring diagram
Voltage supply, checking
- disconnect idle stabilizer valve harness connector
Voltage supply, checking
- disconnect idle stabilizer valve harness connector
Harness connector
- connect multimeter US 1119 between terminal 2 of idle stabilizer valve harness connector and ground
- switch ON ignition
^ approximately battery voltage
Stabilizer circuit, continuity checking
- switch OFF ignition
- connect multimeter US 1119 between terminal 3 of the idle stabilizer valve harness connector and terminal 3 of the disconnected harness connector for the CIS-E control unit
^ zero ohms (continuity)
- connect multimeter US 1119 - between terminal 1 of the idle stabilizer valve harness connector and terminal 4 of the disconnected harness connector for the CIS-E control unit
^ zero ohms (continuity)
If NO
- check for open circuit, using wiring diagram
- reconnect idle stabilizer valve harness connector
- connect multimeter US 1119 between terminals 3 and 4 of the disconnected harness connector of the CIS-E control unit
^ 24-30 ohms
If NO
- replace idle stabilizer valve