Cis With OXS System - Oxygen Sensor System Checking (GROUP 26, NO. 85-01)
Publication date: 1985-04-17Reference number: GROUP 26, NO. 85-01
CIS WITH OXS SYSTEM - OXYGEN SENSOR SYSTEM CHECKING
TECHNICAL SERVICE BULLETIN
CIS WITH OXS SYSTEM - OXYGEN SENSOR SYSTEM, CHECKING
Models: 1985 Volkswagen Golf (U.S. Models with Manual Trans. Only)
Group: 26 - Exhaust System/Emission Controls
Bulletin No.: 85-01
Part Identifier: N/A
Date: April 17, 1985
OXYGEN SENSOR SYSTEM, CHECKING
WORK SEQUENCE
Connect tester VW 1367 as follows.
Connect + lead to positive battery terminal.
Connect - lead to negative battery terminal.
Connect dwell lead to OXS test connection (blue/white and brown wires) using harness adaptor US 1112.
Press % button on tester VW 1367.
Disconnect ignition coil high tension wire from ignition distributor cap and connect to ground with jumper wire.
Remove fuel pump relay from fuse/relay panel.
Switch US 4480/3 OFF.
Connect US 4480/3 in place of fuel pump relay in fuse/relay panel.
Continue with test procedures.
FREQUENCY VALVE, CHECKING
Switch US 4480/3 ON.
- Frequency valve must make buzzing noise.
If YES
Frequency valve OK, go to next test.
If NO
Frequency valve NOT OK, continue as follows.
Unplug frequency valve connector.
Check terminals of connector and frequency valve for correct position or damage.
If terminals OK.
Connect ohmmeter across terminals of frequency valve. See Fig 1 .
- Must read 2-3 ohm.
If ohm reading NOT OK
Replace frequency valve and recheck.
If ohm reading OK.
Check for voltage across terminals of frequency valve connector with test light. See Fig 2 .
- Test light must go on.
If light goes ON
Replace frequency valve and recheck.
If light DOES NOT go on
Check for open circuit in wiring between frequency valve connector, oxygen sensor relay and control unit (refer to current flow diagram).
If circuits OK
Replace oxygen sensor relay.
If light still DOES NOT go on
Replace OXS control unit and recheck system.
OXS CONTROL UNIT, CHECKING
Cold Enrichment
Switch US 4480/3 ON.
Unplug OXS thermoswitch connectors (arrow). See Fig 3 .
Check reading displayed on VW 1367.
- Must be steady 50% +/- 2% (45 +/- 2° dwell).
Bridge terminals of OXS thermoswitch connectors (arrows). See Fig 4 .
Check reading displayed on VW 1367.
- Must be steady 80% +/- 2% (72 +/- 2° dwell).
If either reading NOT OK
Check for open circuit in wiring between connector and OXS control unit.
If wiring OK
Replace OXS control unit.
Remove bridge at connectors.
Check continuity of OXS thermoswitch with ohmmeter. See Fig 5 .
- Above 30°C (86°F) = infinite ohm
- Below 20°C (68°F) = 0 ohm
If readings NOT OK
Replace thermoswitch.
RICH-LIMIT TESTING
- US 4480/3 switched ON
- OXS thermoswitch connector unplugged (if engine cold)
Unplug oxygen sensor at connection and ground green wire.
Check reading displayed on VW 1367.
- Must be at least 87% (78° dwell).
If reading NOT OK
Check for open circuit in wiring to OXS control unit.
If reading OK
Replace OXS control unit.
If reading OK
Continue with lean-limit testing.
OXYGEN SENSOR, CHECKING
- Switch of US 4480/3 ON.
- Thermoswitch connector removed.
Disconnect crankcase ventilation hoses 2 and 3 and vent to atmosphere. See Fig 6 .
Reconnect wire to oxygen sensor.
Reconnect coil wire into distributor cap.
Start engine and hold at 2500 rpm for more than minutes.
Check reading on tester at idle speed (idle speed must be within specifications).
- Reading on tester must fluctuate.
If reading NOT OK (constant at 13% or 87% (12° or 78° dwell) CO may be out of specs. See Product Circular GROUP 25, NO. 85-02 .
If reading is a steady 50% (45° dwell) or constant at specification limits and OXS control unit OK.
Replace oxygen sensor.
Reconnect thermoswitch connector.
Reinstall crankcase breather hoses.
Remove US 4480/3.