Ignition System - Electronic Volvo 780 I

DESCRIPTION

Volvo uses 2 types of the EZK systems. The systems are similar in components and operations. The Volvo 740 and 760 with B230F/FT engines use an EZ117K type. The Volvo 760 and 780 with B280F engines use an EZ115K type.

The EZK system consists of a breakerless Hall Effect distributor, an ignition Electronic Control Unit (ECU), a knock sensor, a LED knock indicator, an amplifier module, ignition coil and a potentiometer and microswitch mounted on the throttle housing.

OPERATION

Inputs from engine speed, engine load, detonation, throttle position and battery voltage are supplied to the microprocessor within the ignition module to determine spark advance. Only the engine load and engine speed input signal values are used to determine the timing signal entered in the memory of the microprocessor. The microprocessor, after analyzing the parameters of engine operation, will adjust timing accordingly.

The ECU output signals provide control for the amplifier module, whose final transistor will make or break the primary coil circuit. The output signals also control the full load enrichening circuit of the injection ECU and the LED knock indicator.

The Volvo B280F engine utilizes 2 knock sensors, one for each cylinder bank. They are located below the intake manifold in the center of the block.

The knock sensors consist of piezo-electric transducers which produce a current within the frequency range which occurs when a cylinder knocks. The ECU will retard ignition timing by 3 degrees for the individual cylinder that developed knocking. When knocking stops, the ECU will hold the retarded ignition timing for a number of revolutions, depending on engine speed.

PRELIMINARY TEST PROCEDURES

Ignition Secondary Checks and Coil Resistance Checks are basic system tests, required whenever ignition problems are suspected. For these tests, refer to IGNITION SYSTEMS TROUBLE SHOOTING in this section. Check for hard codes which may be set in the computer. If any codes are set they must be checked and/or corrected prior to the following testing procedures.

Scheme 1

Scheme 2

Scheme 3

1. Check the ground connections from ignition ECU and power stage to inlet manifold ground to ensure proper connection. If ground connections are good, disconnect one spark plug wire from a spark plug. Attach a test spark plug to the disconnected spark plug wire and ground spark plug, crank engine and monitor spark.
2. A strong Blue-White spark indicates an engine or fuel system malfunction. If no spark or a weak spark is present, reconnect spark plug wire to spark plug. Disconnect coil wire from distributor cap and install test spark plug. Crank engine and monitor spark. If no spark or weak spark is present, the coil or ignition system primary circuit is defective.
3. If a strong Blue-White spark is present, check ignition rotor, distributor housing and spark plug wires. Replace components as necessary. If all the previous steps show no defective components, proceed to next step.
4. Remove air cleaner assembly. Ensure ignition is off and disconnect power stage connector. Remove connector dust cover. (Scheme 1) Attach multimeter negative (-) lead to ground and positive (+) lead to connector pin No. 4. Turn ignition on and note voltage reading. Voltage should be approximately 12 volts.
5. Leave multimeter attached and crank starter motor. Voltage should be approximately 12 volts. If voltage is too low, check battery and charging system. If voltage is not present, check Black wire from ignition ECU to ignition coil and power stage. Repair or replace as necessary.
6. Check power stage ground resistance with multimeter attached between power stage connector pin No. 2 and ground. Resistance should be zero ohm. Check ignition coil resistance with multimeter attached between power stage connector pin No. 1 and No. 4. Resistance should be 0.6-1.0 ohm. If resistance is below 0.6 ohm, check wires for short circuit.
7. If wires are okay but resistance is still below 0.6 or above 1.0 ohm, attach multimeter between ignition coil terminal No. 1 and No. 15. (Scheme 2) If resistance is below 0.6 or above 1.0 ohm install a new ignition coil. If resistance is 0.6-1.0 ohm, check continuity of wires between ignition coil and power stage connector pin No. 1 and No. 4. Repair or replace as necessary.
8. Check shield wire (ground) between ignition ECU and power stage. (Scheme 1) Shield wire should be connected to power stage connector pin No. 3. Repair if necessary. Check that power stage receives ignition ECU signal by disconnecting wires from ignition coil terminal No. 1. Attach positive (+) lead of multimeter to power stage connector pin No. 5 and negative (-) lead to ground.
9. Crank starter motor and monitor voltage reading. Voltage should be 0-2 volts. If voltage is within specifications, install a new power stage and recheck circuit. If a very low voltage is present or voltage continuously fluctuates, check wiring between ignition ECU and crankshaft position sensor. Repair or replace as necessary.
10. Turn ignition off. Reconnect disconnected components. Ensure all connectors are secure and properly connected. With ignition off, remove panel from lower left dashboard and disconnect ignition ECU connector. Remove dust cover from connector. Visually inspect that all pin connection sleeves are at the same height.
11. Attach multimeter positive (+) lead to ignition ECU connector pin No. 6 and negative (-) lead to ground. Turn ignition on. Voltage should be approximately 12 volts. Check resistance of engine RPM position sensor by attaching multimeter leads between ignition ECU connector pin No. 10 and No. 23. (Scheme 3) Resistance should be 500-600 ohms. Check and ensure shield wire (ground) is connected to ECU connector pin No. 11.
12. Turn ignition off. If no defects are found after performing all previous steps, or if engine still malfunctions after repairs, install a new ignition ECU. Recheck system as necessary.

B280F With EZ115K System

1. Check timing with engine at normal operating temperature and idle speed. If timing is not within specifications perform «CIRCUIT CHECK»(/volvo/780/i-1986-1991/remont/ignition-system/#ignition-system-electronic) in this article. If problem still exists, proceed to next step.
2. Check that wires from engine RPM/crankshaft sensor are correctly connected to the connector on left suspension tower. Check continuity of the wires. Repair or replace wire(s) as necessary. If problem still exists, proceed to next step.
3. Turn off ignition. Check that wires from cylinder one position sensor are correctly connected to the connector on left suspension tower. Check continuity of the wires. Repair or replace wire(s) as necessary.

Scheme 4

1. Install LED Tester using manufacturer's instructions. Turn ignition on. Diode light should be on. If light does not come on, check for an open circuit between test point connector wire and pin No. 3 of the ignition ECU. (Scheme 4) Repair and repeat test as necessary.
2. If light did come on, start engine and slowly increase the RPM. The light should go out when engine RPM is greater than 700 RPM. If light does not go out, there is a defect in the ignition ECU or a short circuit in the test point wiring. Repair and repeat testing.
3. After completing steps 1) and 2), test drive the vehicle while monitoring the LED Tester under conditions listed in the following steps. The LED Tester will flash any fault signals received from the ECU.
4. Drive vehicle with full load acceleration, then allow engine speed to drop to idle RPM. If one flash is counted, pre-ignition is indicated. Check for low fuel octane, high engine temperature, defective spark plugs or improper torque, air inlet leakage and excessive carbon build up.
5. Allow vehicle to maintain idle RPM and have helper monitor LED Tester. If 2 flashes are counted, an incorrect temperature sensor signal is indicated. Proceed to «CIRCUIT CHECKS»(/volvo/780/i-1986-1991/remont/ignition-system/#ignition-system-electronic) in this article. If 3 flashes are counted, disregard as not used.
6. If 4 flashes are counted, incorrect knock sensor signal or defective knock detection circuit in ECU is indicated. Proceed to «CIRCUIT CHECKS»(/volvo/780/i-1986-1991/remont/ignition-system/#ignition-system-electronic) in this article.
7. If 5 flashes are counted, incorrect load signal from fuel system ECU is indicated. Proceed to «CIRCUIT CHECKS»(/volvo/780/i-1986-1991/remont/ignition-system/#ignition-system-electronic) in this article. If 6 flashes are counted, incorrect cylinder one position sensor signal is indicated. Proceed to «CIRCUIT CHECKS»(/volvo/780/i-1986-1991/remont/ignition-system/#ignition-system-electronic) in this article.

Scheme 5

B230F/FT With EZ117K System

1. Install LED Tester using manufacturer's instructions. Turn ignition on. Diode light should be on. If light does not come on, check for an open circuit between test point connector wire and ignition ECU connector pin No. 3. (Scheme 5) Repair and repeat test as necessary.
2. If light did come on, start engine and slowly increase the RPM. The light should go out when engine RPM is greater than 920 RPM. If light does not go out, there is a defect in the ignition ECU or a short circuit in the test point wiring. Repair and repeat testing.
3. With step 1) and 2) completed, a test drive of the vehicle is necessary. Using a helper to monitor the LED Tester, the LED Tester will flash according to the fault signal it receives from the ECU. Proceed to the next step.
4. Drive vehicle under full load acceleration. If one flash is counted, pre-ignition is indicated. Check for low fuel octane, high ignition setting, defective spark plugs or improper torque, low fuel pressure or restricted injectors. In hot climates or high altitudes, maximum retard may be encountered. There is no need for concern if engine knock does not occur.
5. Operate engine at 3500 RPM for 5 seconds and allow it to run at idle. If 4 flashes are counted, a safety retard will be activated at high load and there will be a loss of power. Check knock sensor connector and torque. Check for open between knock sensor and ignition ECU. Ensure wires from knock sensor to ignition ECU are not reversed. Check for defective ignition ECU.
6. Operate engine with open throttle switch. If 5 flashes are counted, a defective load signal will cause low ignition advance and loss of power. Check for open circuit between ignition ECU connector pin No. 8 and fuel ECU connector pin No. 24. Check for defective fuel ECU and/or ignition ECU. Proceed to «CIRCUIT CHECKS»(/volvo/780/i-1986-1991/remont/ignition-system/#ignition-system-electronic) in this article.

Scheme 6

1. Turn ignition off. Remove panel from lower left of dashboard. Disconnect ECU connector from ECU. Remove cover from ECU connector. Visually inspect all pin connection sleeves to ensure all pins are at the same height. NOTE: When measuring resistance and voltage at connector, DO NOT probe into front of connector. Probe only through side of connector, just enough to make a good electrical contact. Pin identification is indicated on side of ECU connector.
2. Check temperature sensor circuit using a multimeter to measure resistance. Attach multimeter lead to pin No. 2 (Green wire) of the 8 pin "F" test connector, located on left suspension tower. Attach the other lead to a good ground. If resistance is not within specifications, repeat measurement at sensor(s) to determine if sensor wire(s) or sensor(s) is defective. See «TEMPERATURE SENSOR RESISTANCE»(/volvo/780/i-1986-1991/remont/ignition-system/#ignition-system-electronic) table in this article. Repair or replace as necessary. TEMPERATURE SENSOR RESISTANCE Degrees °F (°C) Resistance - Ohms -22 (-30) 24,000 32 (0) 6000 104 (40) 1200 176 (80) 275 248 (120) 110
3. Check the knock sensor wire resistance with a multimeter. Disconnect the connector at fuel distribution rail. Attach a jumper wire between pin No. 1 and pin No. 2 of fuel distribution rail connector. Attach the multimeter leads between ignition ECU connector pins No. 12 and 13. (Scheme 6) Resistance should be zero ohms. Check resistance between ignition ECU connector pins No. 24 and 25. Resistance should be zero ohms.
4. If resistance is high, an open circuit is indicated. Remove jumper wire from fuel distribution rail connector and check continuity of each wire. Repair or replace as necessary. If wiring is okay but fault code still flashes, incorrect knock sensor signal is indicated.
5. Install a new ignition ECU and repeat test using LED Tester. If LED still flashes fault code, reinstall original ECU and install new knock sensor(s). Repeat test procedures to ensure problem is corrected.
6. Check fuel system ECU load signal with a multimeter set for voltage measurement reading. Attach multimeter leads between ignition ECU connector pin No. 8 and ground. Turn ignition on. Voltage should be approximately 11 volts. If voltage is low or zero, there is an open circuit between the fuel ECU and ignition ECU or a defective fuel ECU.
7. Check cylinder one position sensor using a multimeter set for ohms reading. Attach multimeter leads between ignition ECU connector pins No. 18 and 19. Resistance should be zero ohm. Check that shield wire (ground) is connected to connector pin No. 21. If not within specifications, position sensor is defective.
8. Check throttle switch resistance with multimeter. Attach multimeter leads between ignition ECU connector pin No. 7 and ground. Resistance should be zero ohm. Slowly depress accelerator to open throttle switch. Resistance should increase. If reading is incorrect, measure resistance at throttle switch to determine if wire is broken or if throttle switch is defective.
9. If necessary, check throttle switch adjustment. Open throttle valve slightly and listen for an audible click. The click indicates that throttle switch opens at the same time as the throttle valve. Adjust throttle switch if necessary.
10. Check engine RPM/crankshaft position sensor resistance with a multimeter. Connect multimeter leads between ignition ECU connector pins No. 10 and 23. Resistance should be 500-600 ohms. Check that shield wire (ground) is connected to connector pin No. 11. If not within specifications, replace RPM/crankshaft position sensor.
11. Check that test connector is not grounded using a multimeter. Connect multimeter leads between ignition ECU connector pin No. 13 and ground. Resistance should be infinity. If not within specifications, test connector is either damaged or grounded. The test connector is a one wire (Yellow with Red) connector located at the right front fender in the engine compartment by the air cleaner assembly.
12. Connect multimeter leads between ignition ECU connector pin No. 20 and ground. Resistance should be zero ohm. If not within specifications, repair open circuit.
13. Turn ignition off and reconnect ignition ECU connector. Remove air cleaner assembly to gain access to power stage connector. Disconnect power stage connector and remove connector dust cover. Check ignition coil primary winding resistance with a multimeter.
14. Connect multimeter leads between power stage connector pin No. 1 and No. 4. Resistance should be 0.6-1.0 ohm. If resistance is below 0.6 ohm, check wires for short circuit. If wires are okay and resistance is still below 0.6 ohm or above 1.0 ohm, proceed to next step.
15. Connect multimeter leads between ignition coil terminals. If resistance is below 0.6 ohm or above 1.0 ohm install a new ignition coil and recheck resistance. If resistance is correct, check continuity of wires between ignition coil and connector pins No. 1 and 4. Repair or replace wire as necessary.
16. Attach multimeter leads between terminal No. 1 of ignition coil and coil tower. (Scheme 2) Resistance should be 6500-9000 ohms. If not within specifications, replace ignition coil.
17. Check power stage ground resistance with a multimeter. Attach multimeter leads between power stage connector pin No. 2 and ground. Resistance should be zero ohm. Check shield wire between ignition ECU and power stage. Shield wire should be connected to pin No. 3 of power stage connector.
18. Check for voltage at ignition coil and power stage with a multimeter. Connect multimeter negative (-) lead to ground. Connect multimeter positive (+) lead to power stage connector pin No. 4. Turn ignition on and note voltage reading. Voltage should be approximately 12 volts. Proceed to next step.
19. Crank starter motor and observe voltage reading. Voltage should be at least 10.5 volts. If voltage is too low, check battery and charging system. If there is no voltage, check wires between ignition ECU, ignition coil and power stage. Repair or replace as necessary.
20. Turn ignition off. If no defects were found in the previous steps and problems still exists, install a new ignition ECU and/or power stage. Reconnect disconnected components and recheck system.

Scheme 7

Scheme 8

1. Check for voltage at ignition coil with a multimeter. Attach multimeter negative (-) lead to ground and positive (+) lead to coil terminal No. 15. (Scheme 2) Turn ignition on and note voltage. Voltage should be approximately 12 volts. If no voltage is present, check for broken wire between coil and ignition ECU.
2. Turn ignition off. Disconnect power stage connector and remove dust cover. Connect multimeter negative (-) lead to ground. Turn ignition on. Touch multimeter positive (+) lead to connector pin No. 1 and note voltage reading. Touch positive (+) lead to connector pin No. 4 and note voltage reading. Voltage should be approximately 12 volts.
3. If no voltage is present, check for a broken wire between power stage connector and ignition ECU. Turn ignition off. Check ignition coil resistance. Resistance measurement should be taken at an ambient temperature of 68°F (20°C). Attach multimeter lead between power stage connector pins No. 1 and 4. Resistance should be 0.6-0.9 ohm.
4. If resistance is not within specifications, check resistance at ignition coil. Attach multimeter leads between ignition coil terminals No. 1 and 15. (Scheme 2) Resistance should be 0.6-0.9 ohm. If not within specifications, replace coil assembly and recheck.
5. If resistance is within specifications, check continuity of wires between ignition coil and power stage connector pins No. 1 and 4. Repair or replace as necessary.
6. Turn ignition off and disconnect ignition coil leads. Check ignition coil secondary windings resistance. Attach multimeter leads between ignition coil tower and terminal No. 1 of the coil. (Scheme 2) Resistance should be 6500-9000 ohms. If not within specifications, install a new ignition coil and recheck.
7. Check power stage ground resistance. Turn ignition off. Attach multimeter positive (+) lead to power stage connector pin No. 2 and negative (-) lead to ground. Resistance should be zero ohm. If resistance is other than zero ohm, check continuity of wire between connector pin No. 2 and intake manifold. Repair or replace as necessary.
8. Check shield (ground) wire between ignition ECU connector pin No. 16 and power stage connector pin No. 5. Shield wire should be connected to power stage connector pin No. 3. (Scheme 1)
9. Check voltage signal from ignition ECU to power stage with multimeter. Disconnect Red/White wire from ignition coil terminal No. 1 and Blue wire from coil terminal No. 15. (Scheme 2) Attach multimeter positive (+) lead to power stage connector pin No. 5 and negative (-) lead to ground. Crank starter motor and monitor voltage reading. Voltage should be approximately 2 volts. If no voltage is present, proceed to step 18).
10. Turn ignition off and reconnect ignition coil wires. Reconnect power stage connector. Disconnect distributor electrical connector. Attach multimeter negative (-) lead to ground. Turn ignition on. Touch multimeter positive (+) lead to harness connector pin No. 3. (Scheme 7) Voltage should be approximately 11 volts. If no voltage is present, proceed to step 16).
11. Leave multimeter negative (-) lead attached to ground and attach positive (+) lead to harness connector pin No. 2. Turn ignition on and note voltage reading. Voltage should be approximately 5 volts. If no voltage is present, proceed to step 18). If other than 5 volts are present, replace ignition ECU and recheck.
12. Turn ignition off and check distributor ground resistance. Leave multimeter negative (-) lead attached to ground and attach positive (+) lead to harness connector pin No. 1. Resistance should be zero ohm. If infinite resistance is present, check for poor or no ground connection at ignition ECU connector pin No. 20. Replace defective ignition ECU and perform step 18).
13. Turn ignition off and reconnect distributor electrical connector. Remove panel under steering wheel. Remove ignition ECU from above pedal cluster. Disconnect ECU connector and remove dust cover and side covers. Carefully reconnect connector to ECU. Ensure ignition is off.
14. Disconnect ignition coil Red-White wire and Blue wire. Attach multimeter negative (-) lead to ground and positive (+) lead to ECU connector pin No. 24 at rear of connector. Turn ignition on. Using a helper, turn crankshaft with a wrench and observe voltage reading.
15. As distributor trigger wheel vane passes switch in distributor, voltage should be more than 1.8 volts. Between vanes, the voltage should be 0.0-0.7 volt. If voltage is other than specified, replace hall switch in distributor. Turn ignition off and disconnect multimeter.
16. Ensure ignition is off and disconnect ignition ECU connector. Attach multimeter negative (-) lead to ground and positive (+) lead to ECU connector pin No. 6. Turn ignition on and note voltage reading. Voltage should be approximately 12 volts. If no voltage is present, check continuity of wire and repair or replace as necessary.
17. Leave positive (+) lead attached to connector pin No. 6 and attach negative (-) lead to connector pin No. 20. Voltage reading should be approximately 12 volts. If no voltage is present, check ground connection at intake manifold.
18. Turn ignition off. Check continuity between distributor harness connector and ignition ECU connector as follows: Probe distributor harness connector pin No. 1 and ECU connector pin No. 10. Probe distributor harness connector pin No. 2 and ECU connector pin No. 24. Probe distributor harness connector pin No. 3 and ECU connector pin No. 4. (Scheme 8) Resistance between all pins should be zero.
19. Disconnect power stage connector. Attach multimeter leads between power stage connector pin No. 5 and ECU connector pin No. 16. Resistance should be zero. If continuity is present, replace ignition ECU. If continuity is not present, repair or replace wire. Reconnect power stage connector. Check ignition ECU connector pin No. 3 is not shorted to ground.
20. Ensure ignition is off. Attach multimeter negative (-) lead to ground and positive (+) lead to ECU connector pin No. 7. Resistance should be zero ohm. Depress accelerator pedal slightly. Resistance should increase but never be infinite. If resistance is not within specifications, check resistance at throttle switch to determine if switch is defective or if there is a broken wire(s).
21. Disconnect wiring harness from knock sensor. Attach a jumper wire to both terminals on back of knock sensor connector. Attach multimeter between ignition ECU connector pins No. 12 and 13. If resistance shows zero ohm, remove jumper wire from knock sensor connector. An infinity reading should now be present. If both checks fail, check for broken or shorted wire(s). NOTE: Visually check that circuit wire is connected to ECU connector pin No. 13 and that shield (ground) is connected to connector pin No. 12. Reversed connections will retard ignition timing and cause loss of power.
22. Measure voltage signal from fuel system ECU. Attach multimeter negative (-) lead to ground and positive (+) lead to ignition ECU connector pin No. 8. Turn ignition on. Voltage should be approximately 11 volts. If no voltage is present, check and repair wire between ignition ECU connector pin No. 8 and fuel system ECU connector pin No. 24. If wire and connections are okay, replace fuel system ECU.
23. Turn ignition off. If no faults were found in the previous steps and a problem still exists, install a new ignition ECU and/or power stage. Reconnect all disconnected components.

See also:
• CIRCUIT CHECK