Ignition System - Bosch Hall Effect Volvo 240 I

DESCRIPTION

Note. Ignition system is controlled by the CIS-E electronic control system. See BOSCH CIS-E ELECTRONIC CONTROL SYSTEM in FUEL SYSTEMS section.

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.

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 an 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.

OPERATION

The Hall Effect sending unit is mounted inside the distributor. A trigger wheel passes in and out of the air gap of the Hall Effect sending unit. There is one trigger wheel shutter for each cylinder of the engine.

The Hall Effect sending unit signals the ignition control unit to make and break current flow in the primary circuit of the ignition coil. Secondary voltage is released through the high tension wiring, distributor cap and rotor to the spark plugs.

ADJUSTMENTS

No adjustments should be attempted on ignition system, except spark plug gap and initial ignition timing.

Engine Can be Started

If engine can be started but runs rough or lacks power, perform LIGHT EMITTING DIODE (LED) TEST .

Scheme 4

Scheme 5

Scheme 6

1. Ensure that starting problem is due to ignition system malfunction. Disconnect each spark plug lead, in turn, and attach a spark plug. Ground spark plug and crank engine. If spark is present, check for fuel system or engine mechanical malfunctions.
2. If no spark is present, check for spark at ignition coil by installing a spark plug wire and spark plug to coil tower. Ground spark plug and crank engine
3. If spark is present, check distributor, distributor cap, rotor, and spark plug wires. If no spark is present, check ground points (twin Black leads) on intake manifold. Make sure that connections are clean, tight, and free from corrosion. Clean or repair as necessary.
4. Turn ignition on and measure voltage between coil (terminal No. 15) and ground. Voltmeter reading should be 12 volts. If voltmeter reading is zero, check wiring to ignition coil. Repair wiring as necessary.
5. Disconnect ignition amplifier. Move dust cover to one side and connect voltmeter between terminal No. 1 and ground, then between terminals No. 4 and ground. Connect probes to rear side of connector. Connector can be damaged if probes are inserted into terminals. (Scheme 4): Ignition Amplifier Connector
6. Voltmeter reading should be 12 volts in both terminals. If reading is correct, go to next step. If voltmeter reading is zero, check wiring to ignition amplifier. Repair wiring as necessary.
7. Turn ignition off. Connect ohmmeter across terminals No. 1 and 4 to check coil primary circuit resistance. (Scheme 4) Ohmmeter reading should be.60-.90 ohms at 68°F (20°C). If reading is incorrect, check resistance between coil terminals No. 1 and 15.
8. If reading is now correct, repair wiring between ignition amplifier and ignition coil. If reading is still incorrect, replace ignition coil.
9. Connect ohmmeter across terminal No. 1 and coil tower to check coil secondary circuit resistance. Ohmmeter reading should be 6500-9000 ohms. If reading is incorrect, replace ignition coil.
10. Connect ohmmeter between ground and terminal No. 2 of ignition amplifier. (Scheme 4) Ohmmeter reading should be zero ohms. If reading is incorrect, check ignition amplifier ground wire. Ground wire is connected to intake manifold.
11. Check ignition amplifier terminal No. 5 shielding by making sure shielding is connected to terminal No. 3. Disconnect Red/White wire and Blue wire from ignition coil terminals No. 1 and 15.
12. Connect voltmeter between ground and terminal No. 5 of amplifier terminal. Crank engine. Voltmeter reading should be 2 volts. If okay, connect coil wires and ignition amplifier. If reading is zero volts, see step 24).
13. Disconnect distributor 3-pin connector. Turn ignition on and measure voltage between positive terminal (Red wire) and ground. Voltmeter reading should be 12 volts. If reading is zero volts, check ignition control unit terminals No. 4 and 6. NOTE: Ignition control unit terminals No. 4 and 6 may be checked using steps 20) through 23).
14. Measure voltage between center terminal (Blue wire) and ground. Voltmeter reading should be 4-6 volts. If reading is zero volts, see step 24). If any other voltage is displayed, ignition control unit is defective. Turn ignition off.
15. Measure resistance between negative terminal (Black wire) and ground. Ohmmeter reading should be zero ohms. If ohmmeter indicates infinity, check wiring between connector and terminal No. 10 of ignition control unit. Also check for defective control unit ground (terminal 20). Reconnect distributor. NOTE: Ignition control unit ground may be checked using steps 20) and 21).
16. Remove panel, to right of pedals, in footwell. Remove and disconnect ignition control unit. Remove connector cover and side cover plates from connector. Carefully reconnect ignition control unit.
17. Disconnect Red/White wire and Blue wire from ignition coil to prevent arcing. Turn ignition on. Connect voltmeter between ground and terminal No. 24 (Blue wire) at rear of ignition control unit. (Scheme 5) (Scheme 5): Testing Hall Effect Switch Voltage
18. Turn engine crankshaft in normal direction of rotation with a wrench. Each time trigger wheel vane passes Hall Effect pick-up coil, voltmeter reading should be more than 1.8 volts.
19. Voltage should drop to 0-.7 volts between vanes. If voltage readings are incorrect, Hall Effect pick-up coil is defective. Replace pick-up coil. Turn ignition off and disconnect voltmeter.
20. Disconnect ignition control unit. Turn ignition on. Measure voltage between terminal No. 6 and ground. DO NOT insert voltmeter probe into terminal. Use holes on side of connector. Use only enough pressure to make a good electrical contact. Voltmeter reading should be 12 volts.
21. Measure voltage between terminals No. 6 and 20. Voltmeter reading should be 12 volts. If voltage reading is zero, check ground connections at intake manifold. NOTE: If distributor connector is okay, it is not necessary to perform steps 22) or 23).
22. Turn ignition off. Check continuity between terminal No. 1 of distributor connector and terminal No. 10 of ignition control unit connector. (Scheme 6) Check continuity between terminal No. 2 of distributor connector and terminal No. 24 of ignition control unit connector.
23. Check continuity between terminal No. 3 of distributor connector and terminal No. 4 of ignition control unit connector. Ohmmeter reading should be zero ohms for all 3 checks. If readings are incorrect, repair wiring as necessary. (Scheme 6): Testing Distributor-to-Ignition Control Unit Wiring NOTE: If correct voltmeter reading was obtained when checking terminal No. 5 of ignition amplifier (step 12), it is not necessary to perform step 24).
24. Turn ignition off. Connect ohmmeter between terminal No. 5 of ignition amplifier connector and terminal No. 16 of ignition control unit connector. If ohmmeter reading is zero ohms, wiring is okay. Replace ignition control unit.
25. Connect ohmmeter between ground and terminal No. 3 of ignition control unit connector. Ohmmeter should indicate infinity. If not, terminal No. 3 of ignition control unit is shorted to ground. Repair wiring as necessary.
26. Connect ohmmeter between ground and terminal No. 7 of ignition control unit connector. Ohmmeter reading should be zero ohms. Slightly depress accelerator pedal. Ohmmeter resistance reading should increase. If not, check resistance at throttle switch to see if switch or wiring are defective. NOTE: Ohmmeter should never indicate infinity as throttle switch is connected in parallel with fuel system control unit.
27. Disconnect knock sensor. Install a jumper wire at rear of connector terminals, taking care not to damage them. Check continuity between terminals No. 12 and 13 of ignition control unit connector. Ohmmeter reading should be zero ohms. If circuit is shorted, check each knock sensor wire separately. NOTE: Ensure input wire is connected to terminal No. 13 and shield wire to terminal No. 12 of ignition control unit connector. Reversed wires will retard ignition timing.
28. Connect voltmeter between ground and terminal No. 8 of ignition control unit connector. Turn ignition on. Voltmeter reading should be 11 volts. If voltage is zero, repair fuel system wiring or replace defective fuel system control unit.
29. Turn ignition off. Install side plates on ignition control connector. Install rubber seal and carefully reconnect ignition control unit. Install ignition control unit and panel.
30. If ignition system test did not reveal any faults in ignition system, install a new ignition control unit and/or ignition amplifier.

Test Connections

1. Connect LED tester Red wire to battery positive terminal and Red/Yellow wire to ignition system test point. Ignition system test point wire (Red/Yellow wire) is located on left side of engine compartment. (Scheme 7)
2. Route LED test leads along fender and place LED on dashboard. Road test vehicle and have an assistant monitor LED. The LED will flash according to ignition system malfunctions.

Volvo Light Emitting Diode (LED) Tester. Scheme 7

Continuous LED Light

Start engine. LED should come on and go out as soon as engine speed reaches 920 RPM. If LED does not come on, check for open circuit between test point and pin No. 3 of ignition control unit. If LED does not go out at 920 RPM, check for short circuit in test point wiring. If wiring is okay, ignition control unit is defective.

One Flash

Accelerate engine to full throttle. If engine detonation occurs, initial ignition timing setting is too high, spark plugs are loose, gasoline octane rating is too low, fuel system pressure is too low or fuel injectors are clogged.

4 Flashes

1. Start and run engine at 3500 RPM for 5 seconds prior to testing, then allow engine to return to idle.
2. If safety retard (13 degrees) is activated or if engine lacks power, knock sensor is not connected, knock sensor is loose, wiring is defective from knock sensor to ignition control unit, or knock sensor wiring is reversed.
3. Ensure wires from knock sensor to ignition control unit are connected properly. Green wire goes to pin No. 13 of control unit. Shield from Green wire goes to pin No. 12 of control unit.

5 Flashes

Start engine and open throttle switch. If ignition advance is low or if engine lacks power, check wiring for open between pin No. 24 of LH fuel injection control unit and pin No. 8 of ignition control unit. If wiring is okay, the fuel injection or ignition control units are defective.

DISASSEMBLY

Note. The Hall Effect sending unit and trigger wheel (rotor) cannot be removed on Saab models. Entire distributor must be replaced.

1. Place distributor in soft-jawed vise. Remove distributor rotor and shield. Remove snap ring retaining trigger wheel. Carefully pry off trigger wheel and lock pin. DO NOT lose lock pin.
2. Remove snap ring, Hall switch retaining screws, and plastic pin from underneath distributor connector. Remove trigger plate and connector as an assembly.

Exploded View of Bosch Hall Effect Distributor. Scheme 8

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.

See also:
• LIGHT EMITTING DIODE (LED) TEST