Generators & Regulators: Diagnosis Mitsubishi Eclipse III

TROUBLE SHOOTING

1. Is battery in good condition? If Yes, then go to next step. If No, then charge or replace battery.
2. Is generator drive belt in good condition? If Yes, then go to next step. If No, then adjust belt tension or replace belt.
3. Does charging warning light brightly when ignition switch is turned ON? If Yes, then go to next step. If NO, then: Check ignition switch. Check for burnt-out charging warning light. Check generator. Check charging warning light-related circuits.
4. Does charging warning light go out after starting engine? If Yes, then go to next step. If No, check generator.
5. Is an oscilloscope available? If Yes, go to next step. If No, then go to step 7.
6. Does Oscilloscope show normal wave pattern? If Yes, then go to next step. If No, then check generator.
7. Engine: 2,500 r/min. Headlight: ON (HIGH BEAM). voltage between generator terminal B and positive battery terminal. OK: 0.5V or less. Are generator output line and ground line in good condition? If Yes, then go to next step. If No, check generator output line and ground line.
8. Is output current normal? If Yes, then go to next step. If No, check generator.
9. Is regulated voltage normal? If Yes, then go to next step. If No, check generator.
10. Is voltage drops in generator output line normal? If Yes, generator is normal. Check other systems. In No, then check output line.

GENERATOR OUTPUT LINE VOLTAGE DROP TEST

Required special tool: MB991502: Scan Tool (MUT-II)

This test determines whether the wiring from the generator B-terminal to positive battery terminal (including the fusible link) is in good condition or not

1. Always be sure to check following before testing: Generator installation. Generator drive belt tension. Fusible link. Abnormal noise form generator while engine is running.
2. Tune ignition switch to LOCK (OFF) position. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
3. Disconnect negative battery cable.
4. Disconnect generator output wire from generator B-terminal and connect a DC test ammeter with a range of 0-100A in series between B-terminal and disconnected output wire. (Connect positive lead of ammeter to B-terminal and then connect negative lead of ammeter to disconnected output wire.) NOTE: A clamp-type ammeter which enables measurements to be taken without disconnecting generator output wire is recommended. If voltage may have dropped due to a bad connection at generator B-terminal and generator B-terminal is loosened when test ammeter is connected, connection will be completed at this time and possibility of finding problems will be reduced.
5. Connect a digital-type voltmeter between the generator B-terminal and positive battery terminal. (Connect positive lead of voltmeter to B-terminal and then connect negative lead of voltmeter to positive battery cable. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
6. Reconnect negative battery cable.
7. Connect a tachometer or scan tool MB991502.
8. Leave hood open.
9. Start engine.
10. With engine running at 2,500r/min, turn headlights and other light ON and OFF to adjust generator load so that the value displayed on ammeter is slightly above 30A. Maximum 0.3V. NOTE: When generator output is high and value displayed on ammeter does not decrease to 30A, set value to 40A. Read value displayed on voltmeter at this time. In this the limit value becomes maximum 0.4V. Adjust engine speed by gradually decreasing it until value displayed on ammeter is 30A. Take a reading of value displayed on voltmeter at this time.
11. If value displayed on voltmeter is above limit value, there is probably a malfunction in generator output wire. Check wiring between generator B-terminal and positive battery terminal (including fusible link). If terminal is not sufficiently tight or if harness has become discolored due to overheating, repair and then test again.
12. After test, run engine at idle.
13. Turn off all lights and turn ignition switch to LOCK (OFF) position.
14. Disconnect tachometer or scan tool MB991502. WARNING: Battery posts, terminal and related accessories contain lead and lead compounds. Wash hands after handling.
15. Disconnect negative battery cable.
16. Disconnect ammeter and voltmeter and tachometer.
17. Connect generator output wire to generator B-terminal. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
18. Connect negative battery cable.

Scheme 2

OUTPUT CURRENT TEST

Required special tool: MB991502: Scan Tool (MUT-II).

1. This test, always be sure to check the following: Generator installation. Battery. NOTE: Battery to be used should be slightly discharged. The load in a fully-charged battery will be insufficient and test may not be able to be carried out correctly.
2. Turn ignition switch to LOCK (OFF) position. WARNING: Battery posts, terminal and related accessories contain lead and lead compounds. Wash hands after handling.
3. Disconnect negative battery cable. WARNING: Never use clips to connect line. Loose connections (e.g. using clips) will lead to a serious accident because of high current.
4. Disconnect generator output wire from generator B-terminal and connect a DC test ammeter with a range of 0-100A in series between B-terminal and disconnected output wire. (Connect positive lead of ammeter to B-terminal and then connect negative lead o ammeter to disconnected output wire.) NOTE: A clamp-type ammeter which enables measurements to be take without disconnecting generator output wire is recommended.
5. Connect a voltmeter with a range of 0-20V between generator B-terminal and ground. (Connect positive lead of voltmeter to B-terminal and then connect negative lead of voltmeter to ground.) WARNING: Battery posts, terminal and related accessories contain lead and lead compounds. Wash hands after handling.
6. Connect negative battery cable.
7. Connect a tachometer or scan tool MB991502.
8. Leave hood open.
9. Check to be sure that the reading on voltmeter is equal to battery positive voltage. NOTE: If voltage is 0V, cause is probably an open circuit in wire of fusible link between generator B-terminal and battery positive terminal.
10. After turning light switch ON and turning on headlights, start engine. NOTE: Because current from battery will soon drop after engine is started, step 11 should be carried out as quickly as possible in order to obtain maximum current output value.
11. Immediately after setting headlights to high beam and turning heater blower switch to high revolution position, increase engine speed to 2,500 r/min and read maximum current output value displayed on ammeter. Limit value: 701% of nominal current output. NOTE: For nominal current output. See «GENERATOR MINIMUM OUTPUT SPECIFICATIONS»(ref-155766-S01306307662003062400000). the current output value will depend on electrical load and temperature of generator body. If electrical load is small while testing, specified level of current may not be output even though generator is normal. In such cases, increase electrical load by leaving headlights turned ON for some time to discharge battery or by using lighting system in another vehicle and then test again. The specified level of current also may not be output if the temperature of the generator body or ambient temperature is too high. In such cases, cool generator and then test again.
12. Reading on ammeter should be above limit value. If reading is below limit value and generator output wire is normal, remove generator from engine and check generator.
13. Run engine at idle speed after test.
14. Turn ignition switch to LOCK (OFF) position.
15. Disconnect tachometer or scan tool MB991502. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
16. Disconnect negative battery cable.
17. Disconnect ammeter and voltmeter and tachometer.
18. Connect generator output wire to generator B-terminal. WARNING: Battery posts, terminal and related accessories contain lead and lead compounds. Wash hands after handling.
19. Connect negative battery cable. (Scheme 3)or (Scheme 4).

Scheme 3

Scheme 4

GENERATOR MINIMUM OUTPUT SPECIFICATIONS

REGULATED VOLTAGE TEST

Required special tools

1. MB991502: Scan Tool (MUT-II).
2. MB991519: Generator Harness Connector.

This test determines whether the voltage regulator is correctly controlling the generator output voltage.

1. Always be sure to check the following before test: Generator installation. check to be sure that battery installed in vehicle is fully charged. Generator drive belt tension. Fusible link. Abnormal noise from generator while engine is running.
2. Turn ignition switch to LOCK (OFF) position. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
3. Disconnect negative battery cable.
4. Use special tool (Generator harness connector: MB991519) to connect a digital-type voltmeter between generator S-terminal and ground. (Connect positive lead of voltmeter to S-terminal and then connect negative lead of voltmeter to secure ground or to negative battery terminal.)
5. Disconnect generator output wire from generator B-terminal.
6. Connect DC test ammeter with a range of 0-100A (130A for Diamante) in series between B-terminal and disconnected output wire. (Connect positive load of ammeter to B-terminal and then connect negative lead of ammeter to disconnected output wire.) WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
7. Reconnect negative battery cable.
8. Connect a tachometer or scan tool MB991502.
9. Turn ignition switch to ON position and check reading on voltmeter is equal to battery positive voltage. NOTE: If voltage is 0V, cause is probably an open circuit in wire or fusible link between generator S-terminal and battery positive terminal.
10. Check to be sure that all lights and accessories are off.
11. Start engine.
12. Increase engine speed to 2,500 r/min.
13. Read value displayed on voltmeter when current output by generator becomes 10A or less.
14. If voltage reading conforms to value in voltage regulation table, then voltage regulator is operating normally. See «REGULATOR VOLTAGE SPECIFICATIONS»(ref-155766-S08201718572003062400000). If voltage is outside standard value, there is a malfunction of voltage regulator or generator.
15. After test, lower engine speed to idle speed.
16. Turn ignition switch to LOCK (OFF) position. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
17. Disconnect the negative battery cable.
18. Disconnect ammeter, voltmeter and tachometer.
19. Connect generator output wire to generator B-terminal. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds. Wash hands after handling.
20. Connect negative battery cable. (Scheme 5)or (Scheme 6).

Scheme 5

Scheme 6

REGULATOR VOLTAGE SPECIFICATIONS

Scheme 7

1. Remove generator relay from relay box inside engine compartment. (Scheme 7)
2. Set circuit tester to the Ohms range and check that there is continuity when (+) terminal of tester is connected to terminal 4 of generator relay and (-) terminal is connected to terminal 2.
3. Next, check that there is no continuity when (+) terminal is connected to terminal 2 and (-) terminal is connected to terminal 4.
4. If continuity checks in steps 2 and 3 show defect, replace generator relay.

Scheme 8

Scheme 9

Scheme 10

1. Check continuity between positive rectifier and stator coil lead connection terminal with tester. (Scheme 8) If there is continuity between terminals, diode is shorted, so replace rectifier.
2. Check continuity between negative rectifier and stator coil lead connection terminal with tester. (Scheme 9) If there is continuity between terminals, diode is grounded, so replace rectifier.
3. Check continuity of three diodes by connecting an ohmmeter to both ends of each diode. (Scheme 10) If there is continuity between directions or if there is no continuity, diode is damaged, so replace rectifier.