Idle Stabilizer - Checking/Adjusting Procedures (GROUP 25, NO. 87-06)

Publication date: 1987-10-12
Reference number: GROUP 25, NO. 87-06

IDLE STABILIZER - CHECKING/ADJUSTING PROCEDURES

TECHNICAL SERVICE BULLETIN

Reference Number(s): GROUP 25, NO. 87-06, Date of Issue: October 12, 1987

IDLE STABILIZER - CHECKING/ADJUSTING PROCEDURES

Model(s): 1984-87 Volkswagen Quantum With 5 Cylinder Engine

Group: 25 - Continuous Fuel Injection

Bulletin No.: 87-06

Part Identifier: 2558

Date: October 12, 1987

SERVICE INFORMATION

NOTE: The following article contains 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
AC 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. See Fig 1 .

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. See Fig 2 .
Check idle speed.
800 +/- 70 RPM is the specification.

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. See Fig 3 .

Below 30°C (86°F) = 0 Ohms (continuity)
Above 40°C (104°F) = Infinite 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.

Disconnect idle stabilizer valve harness connector.

Attach multimeter US 1119 to harness connector, set meter to DC volts. See Fig 4 .

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. See Fig 5 .

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. See Fig. .

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). See Fig 7 .

Connect multimeter US 1119 between terminal 11 of relay socket 11 and idle stabilizer valve harness connector. See Fig 8 .

0.0 ohms (continuity)

Connect multimeter US 1119 between terminal 4 of relay socket 12 and idle stabilizer valve harness connector. See Fig 9 .

0.0 ohms (continuity)

Disconnect throttle switch harness connector.

Connect multimeter US 1119 between harness connector and ground, set meter to DC volts. See Fig 10 .

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. See Fig 11 .

Throttle in idle position = 0.0 ohms (continuity)
Throttle slightly open = Infinite ohms (open).

Connect multimeter US 1119 between terminal 13 of relay socket 11 and thermoswitch wire (brown/black). See Fig 12 .

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.

1984 QUANTUM PARTS INFORMATION

Description	Part Number
Automatic transmission	443 907 393 K

CAUTION: Part numbers are for reference only. Consult with your Parts Department for 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. See Fig 13 .

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 appropriate 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. See Fig 14 .

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. See Fig 14 .

If circuit OK

Replace CIS-E control unit.

IDLE STABILIZER VALVE, CHECKING

CONTINUITY, CHECKING

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. See Fig 15 .

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. See Fig 16 .

Zero ohms (continuity).

If NO

Check for open circuit, using appropriate wiring diagram.

VOLTAGE SUPPLY. CHECKING

Disconnect idle stabilizer valve harness connector.

Connect multimeter US 1119 between terminal 2 of idle stabilizer valve harness connector and ground. See Fig 16 .

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. See Fig 15 and Fig 16 .

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. See Fig 15 and Fig 16 .