Charging System Buick Century VI

DESCRIPTION & OPERATION

AD230 generator has high amperage output. AD230 has an outside stator lamination diameter of 130 mm. Generator includes a delta stator, rectifier bridge, and rotor with slip rings and brushes. A built-in regulator incorporates fault detection circuitry. A conventional pulley and dual internal fans are used to cool slip ring end frame, rectifier bridge and regulator.

The generator provides voltage to operate the vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through the rotor. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC by the rectifier bridge and is supplied to the electrical system at the battery terminal.

When the engine is running, the generator turn-on signal is sent to the generator from the PCM, turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists. The PCM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives battery positive voltage that is hot at all times through the 10 amp (GEN) fuse in the underhood fuse block. This voltage is used by the regulator as the reference for system voltage control.

Regulated voltage varies with temperature. System limits voltage by controlling rotor field current while field current is on. Regulator switches rotor field current on and off at a fixed frequency of 400 cycles per second to help control radio noise. By varying overall on/off time, correct average field current for proper system voltage control is obtained. At high speeds, with lower electrical loads, on-time may be 10 percent. At low speeds, with higher electrical loads, on-time may be as much as 90 percent. See GENERATOR SPECIFICATIONS .

COMPONENT LOCATIONS

For component locations, see ELECTRICAL COMPONENT LOCATOR article in ELECTRICAL.

BELT TENSION

Note. Drive belt tension is controlled by a belt tensioner. No adjustment is required.

TROUBLE SHOOTING

Note. For additional information, see CHARGING SYSTEM - GENERAL TROUBLE SHOOTING article in GENERAL INFORMATION.

PRELIMINARY INSPECTION

Verify customer complaint by operating suspected system. Ensure battery is fully charged and passes load test. See BATTERY TESTING & INSPECTION under ON-VEHICLE TESTING. Visually inspect for obvious signs of mechanical and electrical damage. Inspect for blown fuses. See COMPONENT LOCATIONS . Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary. If no fault is found, perform self-diagnostics. See SELF-DIAGNOSTIC SYSTEM .

SYSTEM OPERATION CHECK

Note. Before making electrical checks, visually inspect all terminals for clean, tight connections. Ensure all charging system related fuses are okay. Check generator mounting bolts and drive belt tension. Ensure battery is fully charged and in good condition prior to testing charging system. See BATTERY TESTING & INSPECTION under ON-VEHICLE TESTING. Ensure battery cable connections are in good condition and free of corrosion. Ensure starting system is okay. See STARTERS article in ELECTRICAL.

SELF-DIAGNOSTIC SYSTEM

Note. Diagnostic trouble code tests are written specifically for use with GM Tech I or Tech II scan tools. Generic scan tool can be used but may have limited functions. This article only covers the portion of those systems which relates to charging system diagnosis. For further information, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

RETRIEVING DIAGNOSTIC TROUBLE CODES

See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM under SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

CLEARING DIAGNOSTIC TROUBLE CODES

See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM under SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Circuit Description

The Powertrain Control Module (PCM) monitors the system voltage to make sure that the voltage stays within the proper range. Damage to components, and incorrect data input can occur when the voltage is out of range. The PCM monitors the system voltage over an extended length of time. If the PCM detects a system voltage outside an expected range for the calibrated length of time, DTC P0560 will set.

Conditions For Running DTC

1. System voltage below 11 volts.
2. Engine speed above 1500 RPM.
3. Vehicle speed below 25 MPH.

Conditions For Setting DTC

The PCM detects a system voltage out of range for 2 seconds.

Action Taken When DTC Sets

1. The PCM will not illuminate the Malfunction Indicator Light (MIL).
2. The PCM will command a message to be displayed.
3. The PCM will store conditions which were present when the DTC set as Fail Records data only.

Conditions For Clearing MIL/DTC

1. The PCM will command the message OFF after one trip in which the diagnostic test has been run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Procedure

1. If diagnostic system check was not performed, go to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under ON-VEHICLE TESTING. If diagnostic system check was performed, go to next step.
2. Connect scan tool to Data Link Connector (DLC). DLC is located under instrument panel, near steering column. Turn ignition switch to RUN position. Using scan tool, observe ignition 1 signal parameter in PCM data list. If ignition 1 signal parameter is less than 11 volts, go to next step. If ignition 1 signal parameter is greater than 11 volts, go to step 6 .
3. Using scan tool, compare Battery Voltage parameter in Dash Integration Module (DIM) data list with Ignition 1 Signal parameter. If readings differ more than 0.5 volt, go to next step. If readings differ 0.5 volt or less, perform «TEST A: CHARGING SYSTEM TEST»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under SYSTEM TESTS.
4. Test PCM battery positive circuit for high resistance. See appropriate POWER DISTRIBUTION article. If high resistance was not found, go to next step. If high resistance is found, go to step 7 .
5. Inspect PCM harness connector for poor connections. If connections are okay, go to next step. Repair as necessary, then go to step 7 .
6. Replace PCM. After replacement, reprogram PCM. See «REMOVAL & INSTALLATION»(ref-159248) article in ENGINE PERFORMANCE. Program PCM. After repair, go to next step.
7. Review and record scan tool Fail Records data. Using scan tool, clear DTCs. Operate vehicle at less than 25 MPH with engine speed greater than 1500 RPM. Using scan tool, observe Specific DTC Information for DTC P0560 until test runs. If scan tool indicates DTC P0560 failed this ignition, repeat test beginning at step 3 . If scan tool indicates DTC P0560 passed this ignition, system is okay.

The Powertrain Control Module (PCM) uses the generator turn on signal circuit to control the generator. A high side driver within the PCM allows the PCM to turn the generator ON and OFF. When generator operation is desired, the PCM sends a 5 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the generator is enabled by the PCM, the voltage regulator controls generator output independently of the PCM. Under certain operating conditions, the PCM can turn Off the generator by turning Off the 5 volt signal on the generator turn ON signal circuit. The PCM has fault detection circuitry which monitors the state of the generator turn ON signal circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn on signal circuit, pulling the voltage low. This also causes the PCM to set the DTC.

The PCM receives generator output feedback via the generator field duty cycle signal circuit. The voltage regulator generates a Pulse-Width Modulation (PWM) signal on the field control circuit. The regulator varies the pulse width of this signal in order to control generator output. This signal is also sent to the PCM via the generator field duty cycle signal circuit. The pulse width of the signal is proportional to generator output. The PCM expects generator output to be within a predetermined range under certain operating conditions. If the PCM detects that the PWM signal on the generator field duty cycle signal circuit is not within the expected range, this DTC will set.

When this DTC sets, the PCM sends a class 2 serial data message to the IPC illuminating the Charge indicator light.

The engine is running.

1. The generator turn on signal circuit voltage is low while the PCM is commanding the generator ON.
2. The above condition is present for more than 30 seconds.

or

1. The generator field duty cycle signal PWM is less than 5 percent.
2. The engine RPM is less than 2500.
3. The above conditions are present for more than 30 seconds.

1. The PCM stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Light (MIL) will not illuminate.
3. The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

1. A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
2. The current DTC will clear when the diagnostic runs and does not fail.
3. Use a scan tool in order to clear the MIL diagnostic trouble code.

1. If diagnostic system check was not performed, perform «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under ON-VEHICLE TESTING. If diagnostic system check was performed, go to next step.
2. Connect scan tool to Data Link Connector (DLC). DLC is located below left side of instrument panel. Start engine. Using the scan tool, observe the specific DTC information for DTC P0620 until the test runs. If the scan tool indicates that DTC P0620 has passed this ignition cycle, problem is intermittent. Check wiring and connections. If the scan tool does not indicate that DTC P0620 has passed this ignition cycle, go to next step.
3. Start engine. Using scan tool, command GEN-L terminal ON and OFF. If voltage level does not change with each command, go to next step. If voltage level changes with each command, go to step 6 .
4. Turn ignition switch to OFF position. Disconnect generator harness connector. Turn ignition switch to RUN position. Using scan tool, command GEN-L terminal ON. Measure voltage between ground and generator harness connector terminal "B" (Red wire). Voltage should be 5 volts with generator commanded ON. If voltage is as specified, go to next step. If voltage is not as specified, go to step 7 .
5. Test Red wire for a short or open between generator harness connector terminal "B" and PCM harness connector C2 terminal No. 61. If problem does not exist, go to step 8 . If problem exists, repair as necessary. After repair, go to step 11 .
6. Test Orange wire for a high resistance or open between generator harness connector terminal "D" and 10A GEN fuse located in underhood fuse block mounted to right front strut tower. If problem does not exist, go to next step. If problem exists, repair as necessary. After repair, go to step 11 .
7. Inspect generator harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step 11 . If problem does not exist, go to step 9 .
8. Test B+ circuit for a high resistance or open. If problem does not exist, go to step 10 . If problem exists, repair as necessary. After repair, go to step 11 .
9. Replace the Generator. See «GENERATOR»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under REMOVAL & INSTALLATION. After replacement, go to step 11 .
10. Replace PCM. See «REMOVAL & INSTALLATION»(ref-159248) article in ENGINE PERFORMANCE. Program PCM. After repair, go to next step.
11. Review and record scan tool Fail Records data. Using scan tool, clear DTCs. Start engine. Using scan tool, observe Specific DTC Information for DTC P0620 until test runs. If scan tool indicates DTC P0620 failed this ignition, repeat test beginning at step 2 . If scan tool indicates DTC P0620 passed this ignition, system is okay.

SYSTEM TESTS

SYMPTOM INDEX

1. If diagnostic system check was not performed, perform «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under ON-VEHICLE TESTING. If diagnostic system check was performed, go to next step.
2. The battery must be above a 70 percent state of charge. If battery inspection test was performed, go to next step. If battery inspection test was not performed, see «BATTERY TESTING & INSPECTION»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__battery-testing-inspection) under ON-VEHICLE TESTING.
3. Install a scan tool. Start the engine. With a scan tool, command the GEN-L Terminal OFF and ON. Observe the Ignition 1 Signal parameter. The voltage should change with each command. If voltage changes with each command, go to next step. If voltage does not change with each command, go to step 8 .
4. Turn ON the following accessories: Headlights on high beams. A/C on maximum. Blower fan on high. Heated seats (if equipped). With a scan tool, observe the ignition 1 signal parameter in the engine data list. Increase engine speed to 2500 RPM. Voltage should 12.0-15.5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 6 .
5. Turn OFF all accessories. Turn OFF the ignition. Connect a carbon pile tester to the vehicle. Connect an inductive ammeter probe to the output circuit of the generator. Start the engine. With a scan tool, command the GEN-L Terminal ON. Increase engine speed to 2500 RPM. Adjust the carbon pile as necessary in order to obtain maximum current output of greater than or equal to 94A. If amperage is as specified, system is OK. If amperage is not as specified, go to step 7 .
6. If the voltage measured is greater than 15.5 volts, go to step 12 . If the voltage measured is not greater than 15.5 volts, go to next step.
7. Leave the vehicle accessories ON or maintain load test value. Maintain engine speed at 2500 RPM. Measure the voltage between the generator output terminal and the generator metal housing. If B+ voltage is measured, go to step 14 . If B+ voltage is not measured, go to step 9 .
8. Turn ignition switch to OFF position. Disconnect generator harness connector. Turn ON the ignition, with the engine OFF. Measure voltage between ground and generator harness connector terminal "B" (Red wire). Using scan tool, command GEN-L Terminal ON and OFF. Voltage should be zero volts with generator commanded OFF, and greater than 4.7 volts with generator commanded ON. If voltage is as specified, go to step 14 . If voltage is not as specified, go to step 11 .
9. Maintain engine speed at 2500 RPM and continue to operate generator at load test value. Using a DVOM, measure voltage drop between battery negative terminal and the metal housing of the generator. If voltage drop is 0.5 volt or less, go to next step. If voltage drop is greater than 0.5 volt, go to step 15 .
10. Maintain engine speed at 2500 RPM and continue to operate generator at load test value. Using a DVOM, measure the voltage drop from the output terminal of the generator to the positive terminal on the battery. If voltage drop is 0.5 volt or less, go to step 14 . If voltage drop is greater than 0.5 volt, go to step 16 .
11. Test Red wire for a short or open between generator harness connector terminal "B" and PCM harness connector C2 terminal No. 61. See «WIRING DIAGRAMS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__wiring-diagrams) . If problem does not exist, go to step 13 . If problem exists, repair as necessary. After repair, go to step After repair, go to step 19 .
12. Test Orange wire for a high resistance or open between generator harness connector terminal "D" and 10A DIM fuse located in rear fuse block under left rear seat. If problem does not exist, go to step 14 . If problem exists, repair as necessary. After repair, go to step 19 .
13. Inspect PCM harness connector for poor connections. If problem does not exist, go to step 17 . If problem exists, repair as necessary. After repair, go to step 19 .
14. Inspect generator harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step 19 . If problem does not exist, go to step 18 .
15. Repair high resistance or open in ground circuit of generator. See «WIRING DIAGRAMS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__wiring-diagrams) . After repair, go to step 19 .
16. Test B+ circuit for a high resistance or open. If problem exists, repair as necessary. After repair, go to step 19 .
17. Replace PCM. See «REMOVAL & INSTALLATION»(ref-159248) article in ENGINE PERFORMANCE. Program PCM. After repair, go to step 19 .
18. Replace generator. See «GENERATOR»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under REMOVAL & INSTALLATION. After repair, go to next step.
19. Operate system to verify repair. If system is not operating correctly, repeat test beginning at step 2 .

TEST B: CHARGE INDICATOR ALWAYS ON

1. If diagnostic system check was not performed, perform «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under ON-VEHICLE TESTING. If diagnostic system check was performed, go to next step.
2. Start engine. If battery charge indicator remains illuminated after 5 second bulb check, go to next step. If battery charge indicator does not remain illuminated after 5 second bulb check, problem is intermittent. Check wiring and connections.
3. Install scan tool. Using scan tool, observe Battery Voltage parameter in Instrument Panel Cluster (IPC) data list. If voltage measures 10-15 volts, go to next step. If voltage does not measure 10-15 volts, perform «TEST A: CHARGING SYSTEM TEST»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) .
4. Replace IPC. See ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Go to next step.
5. Operate system to verify repair. If system is not operating correctly, repeat test beginning at step 2 .

TEST C: CHARGE INDICATOR INOPERATIVE

1. If diagnostic system check was not performed, perform «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under ON-VEHICLE TESTING. If diagnostic system check was performed, go to next step.
2. Turn ignition switch to RUN position. If battery charge indicator illuminates during 5 second bulb check, problem is intermittent. Check wiring and connections. If battery charge indicator does not illuminate during 5 second bulb check, go to next step.
3. Replace Instrument Panel Cluster (IPC). See ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Go to next step.
4. Operate system to verify repair. If system is not operating correctly, repeat test beginning at step 2 .

TEST D: GENERATOR NOISE DIAGNOSIS

1. Test generator for proper operation. See «TEST A: CHARGING SYSTEM TEST»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) . After inspection, go to next step.
2. Start engine. Verify that generator noise can be heard. Turn switch to OFF position. Disconnect generator 4-pin harness connector. Start engine. Listen for generator noise. If noise does not exist, go to step 11 . If noise exists, go to next step.
3. Turn switch to OFF position. Remove drive belt. Spin generator pulley by hand. If pulley rotates smoothly and noise does not exist, go to next step. If pulley rotates roughly and/or noise exists, go to step 11 .
4. Inspect pulley for looseness, or loose pulley nut. If pulley and nut are okay, go to next step. If pulley and/or nut is loose, go to step 11 .
5. Loosen all generator mounting bolts. Tighten generator mounting bolts to specification. See «TORQUE SPECIFICATIONS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__torque-specifications) . Install drive belt. Start engine and listen for noise. If noise has decreased or stopped, system is okay. If noise still exists, go to next step.
6. Check for stretched generator connections, or hoses or other equipment rubbing on generator. If problem exists, repair as necessary. After repair, go to next step. If problem does not exist, go to step 8 .
7. Reroute electrical connections, hoses, etc., away from generator. Start engine and listen for noises. If noise has decreased or stopped, system is okay. If noise still exists, go to next step.
8. Check drive belt for proper tension. If drive belt is loose, go to next step. If drive belt is okay, go to step 10 .
9. Replace drive belt tensioner. Start engine and listen for noise. If noise has decreased or stopped, system is okay. If noise still exists, go to step 11 .
10. Check comparable vehicle for similar noise. If noise exists in similar vehicle, system is okay. If noise does not exist in similar vehicle, go to next step.
11. If no definite generator problems were found, ensure all other possible sources of noise are eliminated. If all possibilities have been eliminated, replace generator. See «GENERATOR»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) under REMOVAL & INSTALLATION. After repair, go to next step.
12. Start engine and verify that noise is reduced or eliminated. If noise is still objectionable, go to step 2 .

ON-VEHICLE TESTING

Note. Before making electrical checks, visually inspect all terminals for clean, tight connections. Ensure all charging system related fuses are okay. Check generator mounting bolts and drive belt tension. Ensure battery is in good condition prior to testing charging system. Ensure starter is okay. See appropriate STARTERS article.

BATTERY TESTING & INSPECTION

Note. Manufacturer recommends using Battery Tester (J-42000) for testing battery. Follow instructions provided with tester.

1. Inspect battery for a cracked, broken or damaged case. If battery case is okay, go to next step. If battery case is not okay, go to step 15 .
2. Compare battery Cold Cranking Amperage (CCA) and Reserve Capacity (RC) rating to specifications. See «BATTERY SPECIFICATIONS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) table. If battery meets or exceeds specifications, go to next step. If battery does not meet or exceed specifications, go to step 15 .
3. Turn ignition switch to OFF position. Attempt to rotate negative battery cable connector clockwise with light finger pressure. If negative connector rotates, go to next step. If negative connector does not rotate, go to step 5 .
4. Using an INCH lb. torque wrench, record torque value while loosening negative battery cable bolt. If torque is equal to or greater than 88 INCH lbs. (10 N.m), go to step 9 . If torque is less than 88 INCH lbs. (10 N.m), go to next step.
5. Attempt to rotate positive battery cable connector clockwise with light finger pressure. If battery cable rotates, go to next step. If battery cable does not rotate, go to step 7 .
6. Ensure all electrical loads are off. Follow manufacturers instructions and install Battery Tester (J-42000) to vehicle battery. Follow any instructions displayed on Battery Tester. If Battery Tester passed battery, go to step 14 . If Battery Tester did not pass battery, go to step 8 .
7. Using an INCH lb. torque wrench, record torque value while loosening positive battery cable bolt. If torque is equal to or greater than 88 INCH lbs. (10 N.m), go to step 10 . If torque is less than 88 INCH lbs. (10 N.m), go to next step.
8. Disconnect negative and positive battery cables. Inspect battery and cable terminals for corrosion and defects. Clean and wire brush lead face of both battery terminals and metal contact surfaces on both cable connectors. Remove bolts from both battery cable connectors and inspect for corrosion and defects. If problem exists, repair or replace as necessary. After repair, go to step 11 .
9. Disconnect the negative battery cable. Inspect for the following conditions and repair as needed: The cable bolt is too long or deformed at the end. There is foreign material present inside the nut in the battery terminal. Damage to battery terminal face or cable connector ring. If problem exists, repair or replace as necessary. After repair, go to next step.
10. Disconnect the positive battery cable. Inspect for the following conditions and repair as needed: The cable bolt is too long or deformed at the end. There is foreign material present inside the nut in the battery terminal. Damage to battery terminal face or cable connector ring. If problem exists, repair or replace as necessary. After repair, go to next step.
11. Install Battery Tester (J 42000) to vehicle battery. Follow battery tester manufacturer's instructions. Follow any instructions displayed on battery tester. If battery tester passed battery test, go to next step. If battery tester did not pass battery test, go to step 15 .
12. Press CODE button on battery tester. Record displayed code on vehicle repair order for warranty purposes. Then,, go to next step.
13. Connect positive battery cable to battery and tighten bolt to 13 ft. lbs. (17 N.m). Connect negative battery cable to battery and tighten bolt to 13 ft. lbs. (17 N.m). After cable bolts are properly tightened, battery is okay. Inspection is complete.
14. Press CODE button on Battery Tester. Record displayed code on vehicle repair order for warranty purposes. Battery is okay. Inspection is complete.
15. Replace battery. Inspection is complete.

BATTERY SPECIFICATIONS

BATTERY SPECIFICATIONS

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 4) - Lack of communication may be because of a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
2. 5) - The symptom list in Symptoms will determine the correct diagnostic procedure to use.
3. 6) - The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will collect all the available information before you perform tests.

1. Perform battery inspection test. See «BATTERY TESTING & INSPECTION»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__battery-testing-inspection) under ON-VEHICLE TESTING. After inspection, go to next step.
2. Connect scan tool to Data Link Connector (DLC). DLC is located below left side of instrument panel. Turn ignition switch to RUN position. If scan tool powers up, go to next step. If scan tool does not power up, perform appropriate test. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool. Rotate the ignition switch through all positions while observing the Class 2 Power Mode parameter. The ignition switch parameter reading should match the ignition switch position for all switch positions. If reading is as specified, go to next step. If reading is not as specified, see appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
4. Turn ON the ignition, with the engine OFF. Attempt to communicate with each of the following modules on the class 2 serial data circuit: Body Control Module (BCM). Instrument Panel Cluster (IPC). Powertrain Control Module (PCM). The scan tool should communicate with all modules on the class 2 serial data circuit. If communication is as specified, go to next step. If communication is as not specified, see appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
5. Select display DTC function for each module. Record all displayed DTCs, status of displayed DTCs and module that set DTC. If DTCs are displayed, go to next step. If no DTCs are displayed, repair charging system by symptom. See «SYMPTOM INDEX»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system) table under SYSTEM TESTS.
6. If scan tool displays DTCs which begin with "U", perform appropriate test in accordance with DTC retrieved. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display DTCs which begin with "U", go to next step.
7. If scan tool displays DTCs B1000, B1007, or B1009, perform appropriate test in accordance with DTC retrieved. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display DTCs B1000, B1004, B1007 or B1009, perform appropriate test in accordance with DTC retrieved. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__diagnostic-trouble-code-definitions) .

BENCH TESTING

Note. Manufacturer recommends replacing generator assembly. Bench testing procedures are not provided.

REMOVAL & INSTALLATION

Removal (3.1L)

Note. Generator is serviced as a complete unit only.

1. Disconnect negative battery cable.
2. Remove drive belt from generator.
3. Place coolant recovery reservoir aside for access.
4. Remove the generator rear brace nut (4). Remove bolts (1, 2 & 3) from generator. (Scheme 1)
5. Disconnect electrical connector from generator.
6. Remove protective boot from generator output BAT terminal.
7. Remove generator output BAT terminal nut and remove positive battery lead from generator.
8. Remove generator.

Scheme 1

Installation (3.1L)

1. Position generator to engine.
2. Install positive battery lead to generator.
3. Install generator output BAT terminal nut. Tighten generator output BAT terminal nut to 15 ft. lbs. (20 N.m).
4. Install protective boot to generator output BAT terminal.
5. Connect electrical connector to generator.
6. Install generator bolts (2 & 3) to generator. (Scheme 1)
7. Install generator pivot bolt (1) to generator.
8. Tighten generator bolts in order described. See «TORQUE SPECIFICATIONS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__torque-specifications). The following is a mandatory torque sequence: Tighten generator pivot bolt (1). See Tighten generator bolt (2). Tighten generator bolt (3).
9. Install the generator rear brace nut (4). Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__torque-specifications).
10. Install coolant recovery reservoir.
11. Install drive belt.
12. Connect negative battery cable.

Removal (3.8L)

Note. Generator is serviced as a complete unit only.

1. Disconnect negative battery cable.
2. Remove drive belt from generator.
3. Remove generator rear brace.
4. Remove bolts (1 & 3) and stud (2) from generator. (Scheme 2)
5. Disconnect electrical connector from generator.
6. Position aside protective boot from generator output BAT terminal for access.
7. Remove generator output BAT terminal nut and remove positive battery cable from generator.
8. Remove generator.

Scheme 2

Installation (3.8L)

1. Position generator to engine.
2. Install positive battery lead to generator.
3. Install generator output BAT terminal nut. Tighten generator output BAT terminal nut to 15 ft. lbs. (20 N.m).
4. Install protective boot to generator output BAT terminal.
5. Connect electrical connector to generator.
6. Install generator stud (2) to generator bracket. (Scheme 2)
7. Install generator bolts (1 & 3) to generator bracket.
8. Tighten generator bolts and stud in order described. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/century/vi-1997-2005/remont/charging-system/#charging-system__torque-specifications). The following is a mandatory torque sequence: Tighten generator bolt (1). Tighten generator stud (2). Tighten generator rear bracket bolt (3).
9. Install generator rear brace.
10. Install drive belt.
11. Connect negative battery negative cable.

OVERHAUL

Note. All generators are serviced by replacement only.

GENERATOR SPECIFICATIONS

GENERATOR SPECIFICATIONS

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

WIRING DIAGRAMS

For wiring diagram, see

1. For 2003, «STARTING/CHARGING»(ref-154365-S14039913752003080900000) under SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
2. For 2004, «STARTING/CHARGING»(ref-164753-S08602931082004081600000) under SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

See also:
• COMPUTER RELEARN PROCEDURES
• RETRIEVING DIAGNOSTIC TROUBLE CODES
• CLEARING DIAGNOSTIC TROUBLE CODES
• GENERATOR SPECIFICATIONS
• BATTERY TESTING & INSPECTION
• COMPONENT LOCATIONS
• SELF-DIAGNOSTIC SYSTEM
• P0560
• B
• C
• D
• WIRING DIAGRAMS
• TORQUE SPECIFICATIONS
• DIAGNOSTIC TROUBLE CODE DEFINITIONS