Ignition System - Volvo/chrysler Hall Effect Volvo 240 I

DESCRIPTION

Volvo/Chrysler ignition system is breakerless and includes a knock sensor to monitor and control ignition knock and ping. Knock sensor converts mechanical vibration into electrical signals. Ignition control unit is programmed to react to the signals whose frequencies are characteristic of combustion chamber noise and change ignition timing to compensate. (Scheme 7)

Control receives inputs from the distributor Hall effect sender, throttle switch and knock sensor. Control unit senses engine load through manifold vacuum. All of these inputs are used to maintain optimal ignition timing for all engine operating conditions.

Schematic Of Volvo/Chrysler Ignition System. Scheme 7

TROUBLE SHOOTING

DISABLING IGNITION SYSTEM

Disable ignition system to prevent engine from starting and prevent discharge of high voltage while working on ignition system.

Disconnect wire from terminal 1 (-) on ignition coil and tape wire end to insulate from making contact with engine components.

NO SPARK OR WEAK SPARK TROUBLESHOOTING CHART

Check For Spark

1. Remove spark plug wire from spark plug and attach to known good plug.
2. Ground outer electrode of plug on engine. NOTE: An excessive gap between plug and ground can damage ECU. NOTE: If ignition system failure is not the problem, engine may start during this test. Shut off engine immediately if engine starts to avoid damage to catalytic converter.
3. Visually inspect plug while assistant cranks engine. Spark should be bright blue. If spark is yellow-orange check condition of components. See «VISUAL INSPECTION»(/volvo/240/i-1974-1993/remont/testing-diagnostics/#ignition-system-volvochrysler-hall-effect) . If there is no spark, test electrical system components. See «ELECTRICAL TESTS & FAULT TRACING»(/volvo/240/i-1974-1993/remont/testing-diagnostics/#ignition-system-volvochrysler-hall-effect__electrical-tests-fault-tracing) .
4. If a spark is observed but engine still will not start, refer to BASIC PROCEDURES article in ENGINE PERFORMANCE section.

FIRING ORDER

Firing order is 1-3-4-2 where cylinder No. 1 is at front of engine. Distributor rotates clockwise when viewed from driver's side of vehicle.

Distributor Cap & Rotor

Remove clips and remove cap. Check contacts inside cap and tip of rotor for carbon tracks, wear or pitting. Cracks or carbon tracking in cap may cause shorts to ground. Check that center black carbon brush cap springs back when compressed. If any faults are found, replace cap and/or rotor.

Spark Plug Wires

Gently bend wires in several places. Cracks may cause voltage leaks. Peel back rubber boots and check for pliancy and ability to seal out dirt and moisture. Replace wires if they are dry, cracked, oil-soaked or brittle.

Ignition Coil

Check coil for cracks, burns, carbon tracks or leaking fluid. Coil tower and center terminal should be clean and dry. If necessary, remove coil for cleaning and examination. Verify that wiring at coil top is not contacting metal coil housing. Loosen nut and reposition if necessary.

Primary Wires

Check for corrosion or damage. Clean and repair if necessary. Corroded or loose connections may interfere with signals required for proper operation.

ELECTRICAL TESTS & FAULT TRACING

Note. Tests must be done in order. Perform steps in QUICK CHECK and VISUAL INSPECTION before performing the following tests.

Note. For accurate results, ensure that battery is fully charged, there is fuel in tank, and that the ambient temperature is between 32° and 104°F (0°-40°C).

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

1. Check harness connectors at: ECU, distributor and two at firewall. Check that ground wire on intake manifold is tight and free from corrosion. CAUTION: DO NOT disconnect harness connector from control unit. Connector uses one way sleeve that is damaged when disconnected. If harness connector is removed or control unit is replaced, complete wiring harness must be replaced.
2. Check that vacuum hose to control unit is connected and in good condition. Replace if oil-soaked, dry, cracked or brittle. Disconnect and check for strong vacuum with engine running at 1,500 RPM.
3. Check for power and ground at ECU. (Scheme 8) Backprobe ECU harness connector and check for continuity between terminal 10 and ground. Turn ignition switch to ON and check for battery voltage between terminal 2 and ground. If not okay, check for faults in wiring to connector. (Scheme 8): ECU & Connector Terminal Identification
4. Check for power to coil. Turn ignition switch to ON. Check for voltage between coil terminal 15 and ground. Turn ignition OFF. If not okay, check for faults in wiring to coil.
5. Check coil primary and secondary resistance. (Scheme 9) Disconnect and mark all wires from coil. Check for resistance between primary terminals 1 and 15. Resistance should be 1.1 to 1.3 Ohms. Check for resistance between secondary terminal 1 and center tower. Resistance should be 9,600 to 11,600 Ohms. If values are not as specified, replace coil. (Scheme 9): Checking Primary & Secondary Coil Resistance
6. Check ECU switching function. With ignition OFF, disconnect harness connector from distributor Hall sender. Remove a spark plug, reconnect the plug wire and ground plug to engine. Turn ignition to ON. Briefly jumper between terminals B and C in connector. (Scheme 10) Each time terminals are jumpered, plug should fire strong spark. If car does not start, but plug fires during test, replace Hall sender. If plug does not fire, proceed to step 7). (Scheme 10): Jumpering Distributor Harness Connector
7. Check for power to Hall sender. If plug does not fire, turn ignition on and check for voltage at terminal A in Hall sender connector. (Scheme 11) If voltage is not present, check wire between control unit and Hall sender. If wire is okay, and coil is okay, replace ECU. (Scheme 11): Test Light Check At Distributor Harness Connector
8. Check throttle switch. With ignition OFF, open throttle pulley slowly and listen for click as throttle comes off its stop. If click is not heard, loosen retaining screws. Rotate switch clockwise slightly and turn counterclockwise until it just contacts stop. (Scheme 12) Tighten screws and recheck. If click is not heard at all, replace throttle switch. (Scheme 12): Throttle Switch Rotation
9. Check knock sensor signal. Connect timing light. See «IGNITION TIMING»(/volvo/240/i-1974-1993/remont/testing-diagnostics/#ignition-system-volvochrysler-hall-effect__ignition-timing). Start engine and allow to reach operating temperature. Increase engine speed to 1,500 RPM and hold throttle with screwdriver. Using a hammer, gently tap cylinder block near sensor. (Scheme 13) Timing should change by a maximum of 6°. If timing does not change and throttle switch is correctly adjusted, replace knock sensor.

Knock Sensor Location. Scheme 13

Note. If engine knock is detected, timing is retarded in 2° steps every 20 milliseconds, with a maximum of 6° retard. When knocking is no longer detected, timing begins advancing in 1° steps every 20 milliseconds.

Removal

1. Unhook two springs clips from sides of distributor cap and pull off cap. Leave spark plug wires attached.
2. Pull rotor straight off distributor.

Installation

1. Install new rotor. Ensure that rotor engages notch in distributor shaft.
2. Clip new cap on distributor. Transfer spark plug wires one at a time from old cap the new cap to maintain firing order.

1. Turn engine to Top Dead Center by hand. Scribe matching marks on distributor and cylinder block.
2. Unhook two springs clips from sides of distributor cap and pull off cap. Leave spark plug wires attached.
3. Remove harness connector from side of distributor.
4. Remove clamp down bolt and bracket. Pull distributor from cylinder head. Inspect O-ring on distributor shaft and replace if faulty.

Scheme 14

1. Align rotor to notch on distributor housing. Turn rotor clockwise 30° and install distributor. (Scheme 14) Rotor should be aligned with notch when distributor is seated in position. (Scheme 14): Distributor Rotor Alignment
2. Install clamp down bracket and tighten mounting bolt finger tight.
3. Rotate distributor until matching marks are aligned. Install cap. Adjust timing. See «IGNITION TIMING»(/volvo/240/i-1974-1993/remont/testing-diagnostics/#ignition-system-volvochrysler-hall-effect__ignition-timing).

Scheme 15

1. Disconnect negative cable from battery.
2. Remove distributor, rotor and dust shield. (Scheme 15) Remove circlip above trigger wheel. Using two screwdrivers, carefully pry up trigger wheel. Remove and save trigger wheel locating pin. (Scheme 15): Exploded View Of Bosch Distributor CAUTION: DO NOT bend trigger wheel. If trigger wheel is bent it must be replaced.
3. Remove circlip and spacer from above Hall sender. Pry off plastic connector housing from side of distributor. Lift sender from distributor. Ensure that spacer underneath Hall sender does not come out with sender.
4. Installation is reverse of removal. (Scheme 16)

Trigger Wheel & Locating Pin. Scheme 16

1. Disconnect negative cable from battery.
2. Remove distributor, rotor and dust shield.
3. Pry open two spring clips holding sender to distributor. (Scheme 17) Remove sender.

Hall Sender Retaining Clip Locations. Scheme 17

Install sender into distributor and press in retaining clips. Ensure wiring is positioned so that it is not damaged by rotor. Installation is reverse of removal.

Disconnect knock sensor harness from sensor. Remove knock sensor from engine block by unscrewing.

Clean mounting surface and sensor threads in block. Thread sensor into block and tighten. Connect harness connector.

IGNITION TIMING

Scheme 18

1. Connect a timing light and a tachometer according to equipment manufacturer's instructions. Start engine and run until it reaches operating temperature.
2. Disconnect and plug vacuum line to ECU. Ensure idle speed is 750 RPM. See appropriate BASIC PROCEDURES article in ENGINE PERFORMANCE section.
3. Point timing light at marks on flywheel. (Scheme 18) Timing should be 12 +/- 2° @ 750 RPM. If timing is incorrect, loosen distributor clamp bolt and rotate distributor until marks are aligned. Tighten bolt. (Scheme 18): Timing Mark Location
4. Stop engine. Disconnect test equipment. Reconnect vacuum line at ECU.

See also:
• DISABLING IGNITION SYSTEM
• VISUAL INSPECTION
• ELECTRICAL TESTS & FAULT TRACING
• IGNITION TIMING