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Ignition System - Bosch Hall Effect Volkswagen Golf Mk1

Ignition System 3 illustrations ~2159 words

DESCRIPTION

The typical Bosch Hall Effect electronic ignition system consists of an ignition coil, Hall Effect sending unit (in distributor), Hall control unit, distributor, spark plug wires, and spark plugs.

Volkswagen 1.8L High Output engines use Bosch fully electronic Hall Effect ignition system. The Hall Effect sending unit receives voltage directly from the electronic control unit. Signals from the sending unit are sent to the Hall control unit through the electronic ignition control unit.

During engine operation, ignition timing is controlled by the electronic ignition control unit after receiving signals from the knock sensor, idle switch, full throttle switch, and engine vacuum (vacuum hose is connected directly into ignition control unit).

OPERATION

The Hall Effect sending unit is mounted inside the distributor on a switch plate. A trigger wheel attached to the distributor shaft under the rotor, passes in and out of the air gap of the Hall Effect sending unit. There is 1 trigger wheel shutter for each cylinder of the engine. Shutter width determines dwell, which is not adjustable.

At speeds greater than 940 RPM, the Hall Effect sending unit signals the ignition control unit to make and break current flow in the primary circuit of the ignition coil.

As the ignition control unit breaks the primary circuit through the coil, secondary voltage is released through the high tension wiring, distributor cap and rotor to the spark plugs.

The idle stabilizer is mounted on the same bracket as the Hall control unit and is wired between the distributor and the Hall control unit. It senses engine speed earlier, causing ignition timing to advance.

Advancing ignition timing causes idle speed to increase, and the Hall generator to resume its normal operation.

PRE-TEST PROCEDURES

  1. Ensure the battery is fully charged and in good condition before making tests. Check all wiring harnesses, ignition switch, ignition coil connections, spark plug cables and connectors.
  2. DO NOT connect any condenser to terminal 1 of ignition coil. Connect and disconnect test instruments only when ignition is off. DO NOT touch or remove high tension wires when engine is running or cranking.
  3. Disconnect ignition wires only when ignition is off. DO NOT crank engine unless high tension wire is removed from distributor cap and grounded with a jumper wire.
  4. When installing suppressors, use only 1000 ohms for high tension wires and 1000-5000 ohms for spark plug connectors. DO NOT wash engine when it is running. DO NOT use a battery charger for more than 1 minute nor exceed 16.5 charging voltage.

All Models (Except GLI & GTI)

  1. Connect tachometer and timing light to engine. Disconnect vacuum hose from vacuum advance diaphragm. Start and run engine at 800-1000 RPM. Check ignition timing and adjust if necessary.
  2. Slowly increase engine RPM. Centrifugal advance mechanism should start advancing timing at 1100-1350 RPM. Ignition timing should advance 12-17° at 2600 RPM. Ignition timing should advance 23-27° at 6000 RPM.
  1. Connect tachometer and timing light to engine. Connect Vacuum Advance Tester (VW 1368 ) and hand-held vacuum pump to vacuum advance diaphragm. Turn on tester.
  2. Start and run engine at 800-1000 RPM. Check ignition timing and adjust if necessary. Using pump, apply vacuum until ignition timing begins to change. Record vacuum. Vacuum advance mechanism should start advancing timing at 4-5 in. Hg (100-160 mbar on tester).
  3. Increase vacuum until timing stops advancing. Vacuum advance should be 10-14° at 7-8 in. Hg (180-195 mbar). If necessary, reduce engine RPM to below 1000 RPM to obtain reading.
  1. Disconnect Hall control unit. Set Digital Multimeter (US 1119 ) on 20 volt scale. Connect multimeter between negative terminal 2 and positive terminal 4 of Hall control unit connector.
  2. Turn ignition on. Meter should indicate battery voltage. If reading is incorrect, find open wire in circuit and repair as necessary. Turn ignition off and reconnect control unit.
  3. Remove terminal on Hall Effect sending unit. Connect digital multimeter between negative terminal 1 and positive terminal 15 on ignition coil. Turn ignition on.
  4. Initial meter reading should be 2 volts minimum, then voltage must drop to zero after 1-2 seconds. If reading is incorrect, replace Hall control unit.
  5. Check ignition coil and see if any sealing compound has leaked out. Replace coil if necessary. Briefly tap connector center terminal against engine ground.
  6. Displayed voltage must increase a minimum of 2 volts for a short time. If reading is incorrect, find open in center wire and repair as necessary. If okay, replace Hall control unit. Turn ignition off. Connect multimeter to outer terminals from sending unit.
  7. Turn ignition on. Voltage reading must be 5 volts minimum. If there is still a problem in spite of correct voltage readings, try to find fault in wiring between sending unit and Hall control unit. If no fault can be found replace control unit.
  8. If wiring, ignition coil, and Hall control unit are okay, disconnect coil high tension wire from distributor and connect to ground. Remove rubber grommet from connector at Hall control unit. DO NOT disconnect unit.
  9. Connect multimeter between connector terminal 3 and 6. Turn ignition on. Turn engine crankshaft, by hand, and note reading on meter. Voltmeter should display 0-2 volts alternating voltage. If not, Hall Effect sending unit is defective.

ELECTRONIC IGNITION CONTROL UNIT TEST

Note. Perform this test on GLI and GTI models only. Test Lamp (US 1115) must be connected to battery positive terminal before connecting it to terminal 1. Use of "standard" test lamps can damage ignition system components.

Knock Sensor Test

  1. Connect Test Lamp (US 1115 ) to battery positive terminal and to terminal 1 (single connector with Blue wire). (Scheme 1) Test lamp Light Emitting Diode (LED) must light up.
  2. Start and accelerator engine to over 3000 RPM (1 time only). Test lamp LED must go off. If LED goes out, knock sensor test is completed.
  3. If LED does not go out, connect a jumper wire between terminal 1 and ground for a minimum of 3 seconds. Test lamp LED must start blinking. If lamp blinks in intervals of 2, the knock sensor circuit is defective.
  4. Check knock sensor tightness. If loose, tighten knock sensor to 96 INCH lbs. (11 Nm). Check for open circuit in knock sensor wiring. If wiring is okay, knock sensor and/or control unit is defective.

Knock Sensor Test. Scheme 1

Scheme 1: Knock Sensor Test
Scheme 1: Knock Sensor Test

Timing Advance Test

  1. Perform «KNOCK SENSOR TEST»(/volkswagen/golf/mk1-1974-1993/remont/ignition-system/#ignition-system-bosch-hall-effect__knock-sensor-test) . If knock sensor circuit is okay, check that terminal 11 at ignition control unit is being used and grounded. Connect Timing Tester (VW 1367 ). Start and run engine at idle. Base ignition timing will be indicated on tester.
  2. With engine running, pull vacuum hose off ignition control unit. Increase engine speed to 4300 RPM. Note reading on tester. To determine ignition timing advance, subtract base ignition timing from reading.
  3. Ignition timing advance should be close to 14°. If timing is incorrect, check ground wire at terminal 11 of ignition control unit connector. If wire is okay, ignition control unit is defective.

HALL EFFECT SENDING UNIT TEST

Note. Perform this test only if spark is absent on GLI and GTI models. Use Test Lamp (US 1115 ) only. Use of "standard" test lamps can damage ignition system components.

  1. Disconnect Hall control unit (in glove box). Connect Test Lamp (US 1115 ) between terminal 4 and 6 of control unit connector. (Scheme 2) Turn ignition on.
  2. Crank engine and check signal from Hall Effect sending unit. If test lamp LED flickers, sending unit is okay. Testing is completed. If LED does not flicker, disconnect sending unit connector at distributor.
  3. Connect test lamp to outer connector terminals and turn ignition on. Test lamp LED must light up. If not check voltage supply from ignition control unit to sending unit.
  4. Push up rubber sleeve on sending unit connector. Connect test lamp between center wire on sending unit connector and battery positive terminal. Crank engine and check signal from sending unit. If test lamp LED flickers, sending unit is okay. If not, sending unit and/or ignition control unit is defective.

Hall Control Unit Test. Scheme 2

Scheme 2: Hall Control Unit Test
Scheme 2: Hall Control Unit Test

HALL CONTROL UNIT TEST

Note. Perform this test on GLI and GTI models only. Use Test Lamp (US 1115 ) only. Use of "standard" test lamps can damage ignition system components.

  1. Disconnect Hall control unit (in glove box). Set Digital Multimeter (US 1119 ) on 20 volt scale. Connect multimeter between terminal 2 (negative) and 4 (positive) of control unit connector. Turn ignition on. Voltmeter should indicate battery voltage. If not, repair circuit in wiring.
  2. Connect Test Lamp (US 1115 ) to terminal 4 and 6 of control unit connector. (Scheme 2) Crank engine and check signal from sending unit. If test lamp LED flickers, sending unit is okay. If not, turn ignition off and reconnect Hall control unit.
  3. Remove connector from sending unit at distributor. Connect multimeter between negative terminal 1 and positive terminal 15 on ignition coil. Turn ignition on.
  4. Initial meter reading should be 2 volts minimum, then voltage must drop to zero after 1-2 seconds. If reading is incorrect, replace Hall control unit.
  5. Check ignition coil and see if any sealing compound has leaked out. Replace coil if necessary. Briefly tap connector center terminal against engine ground.
  6. Displayed voltage must increase a minimum of 2 volts for a short time. If reading is incorrect, replace Hall control unit. Turn ignition off and reconnect sending unit.

Perform this test on GLI and GTI models only.

  1. With ignition off, disconnect ignition control unit. Set Digital Multimeter (US 1119 ) on 20 volt scale. Connect voltmeter negative lead to terminal 3 and positive lead to terminal 5 at connector. Turn ignition on.
  2. Meter should indicate battery voltage. If no voltage is present, check fuse 18 on fuse block. If okay, check ground connection at intake manifold. Check wire 5 to ignition switch.
  3. Connect voltmeter negative lead to terminal 3 and positive lead to terminal 8 at connector. Turn ignition on. Actuate full throttle switch. Meter should indicate battery voltage.
  4. If no voltage is present, voltage supply (center wire) to throttle switch is open. If not, full throttle switch is defective. Replace full throttle switch.
  5. Connect voltmeter negative lead to terminal 3 and positive lead to terminal 6 at connector. Turn ignition on. Meter should indicate battery voltage. If no voltage is present, wire to idle switch is open. If not, idle switch is improperly adjusted and/or defective.
  6. Connect voltmeter negative lead to terminal 3 and positive lead to terminal 10 at connector. Turn ignition on. Meter should indicate battery voltage. If no voltage is present, wire to fuel pump relay is open. Repair wire as necessary.
  7. Turn ignition off. Set multimeter to ohm scale. Connect ohmmeter between connector terminals 2 and 3. Ensure that CIS-E fuel control unit is connected. Ohmmeter reading must be 90,000-100,000 ohms. If reading is incorrect, wire 2 to CIS-E control unit is open. If not, CIS-E control unit is defective.
  8. Connect ohmmeter between connector terminals 3 and 4. Connect test connector in engine compartment to ground. Ohmmeter should indicate continuity to ground.
  9. Connect ohmmeter between connector terminals 3 and 11. Ohmmeter should indicate continuity. If no continuity is indicated, ground wire between terminal 3 and 11 is open. Repair as necessary.
  10. Connect ohmmeter between connector terminals 3 and 12. Disconnect Hall control unit and install a jumper wire between terminals 4 and 6. Ohmmeter should indicate continuity.
  11. Connect ohmmeter between connector terminals 3 and 13. Ohmmeter should indicate 1 milliohm. If reading is incorrect, wires to knock sensor are open or knock sensor is defective.
  12. Connect ohmmeter between connector terminals 3 and 14. Ohmmeter should indicate 300,000 ohms. If reading is incorrect, wires to knock sensor are open or knock sensor is defective.
  13. Connect ohmmeter between connector terminals 7 and 15. Disconnect Hall Effect sending unit and install a jumper wire between terminals 1 and 3. Ohmmeter should indicate continuity.
  14. Connect ohmmeter between connector terminals 7 and 9. Disconnect Hall Effect sending unit and install a jumper wire between terminals 1 and 2 (Brown/White wire). Ohmmeter should indicate continuity.

TROUBLE SHOOTING

Note. See the TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

DISASSEMBLY

  1. Loosen ground strap and remove static shield from distributor cap. (Scheme 3) Remove cap, rotor, carbon brush and spring. Remove dust cover. Remove connector from distributor by depressing retaining clip.
  2. Remove retaining snap ring. Carefully pry off trigger wheel. Remove washers. Remove screws and lift out Hall sending unit and connecting socket. Remove base plate and vacuum unit. Remove pin and distributor drive pinion and shims.

Exploded View of Bosch Hall Effect Distributor. Scheme 3

Scheme 3: Exploded View of Bosch Hall Effect Distributor
Scheme 3: Exploded View of Bosch Hall Effect Distributor

REASSEMBLY

  1. To assemble, reverse disassembly procedure. If a new Hall Effect sending unit (generator) is being installed, a special repair kit is available containing all necessary parts.
  2. Replace seals, and check components for cracks, corrosion and wear. Clean cap before installing. If trigger wheel was bent during removal, it must be replaced.