Charging System - Generators & Regulators: Diagnosis Ford Explorer III

TROUBLE SHOOTING

Note. For trouble shooting charging system, see BASIC TROUBLE SHOOTING article in GENERAL INFORMATION.

PRELIMINARY INSPECTION

Ensure battery posts and cables are clean and tight. Inspect drive belt. Ensure connections at generator, regulator and engine ground are clean and tight. Inspect fusible links (2 Gray 12 gauge and one Brown 18 gauge) and central junction box fuse No. 21 (5-amp). Turn ignition on and ensure warning light operates. Check bulb and circuit, if necessary. Start engine and verify charge warning light goes out. If problem is found, repair as necessary. If problem is not found, repair by symptom. See SYMPTOM INDEX table under SYSTEM TESTS.

BATTERY LOAD TEST

Connect battery tester according to tool manufacturer's instructions. Load test battery at approximately one-half cold-cranking amperage rating for 15 seconds while observing battery voltage. If voltage reading is 9.6 volts or more, battery is okay. If voltage reading is less than 9.6 volts, charge battery and retest. If loaded battery voltage is still less than 9.6 volts after charging battery, replace battery.

BATTERY TEST WITH DIGITAL BATTERY ANALYZER

Connect digital battery analyzer to battery and follow on screen instructions. If battery test good, return to service. If battery does not test good, replace battery.

GENERATOR LOAD TEST

1. Ensure drive belt is in good condition. Replace belt as necessary. If belt is okay, connect charging system load tester in accordance with manufacturer's instructions. Start and run engine at 2000 RPM and apply load until generator output levels off.
2. Record maximum generator output current. See «GENERATOR OUTPUT SPECIFICATIONS»(ref-139561-S36452082992002050100000) . With engine running, turn A/C (if equipped) and headlights on, turn blower motor to high speed. Voltage should increase a minimum of .5 volt. If generator output is 10-20 percent of rated amperage, generator output is okay. If generator does not produce rated output, go to «NO-LOAD TEST»(ref-139561-S37470455162002050100000) .

GENERATOR NO-LOAD TEST

Connect voltmeter positive lead to generator B+ terminal, or battery and negative lead to ground. Start and run engine at 2000 RPM with all accessories off. Read voltmeter when voltage stabilizes. Voltage should be 13-15 volts.

PARASITIC DRAW TEST

Check for current drains on the battery in excess of 50 milliamps (0.050 amp) with all the electrical accessories off and the vehicle at rest. Current drains can be tested with the following procedure

1. Make sure the junction box/fuse panels are accessible without turning on interior and underhood lights.
2. Drive the vehicle at least 5 minutes and over 30 MPH to turn on and exercise vehicle systems.
3. Allow the vehicle to sit with the key off for at least 40 minutes to allow modules to time out/power down.
4. Connect a fused jumper wire between the negative battery cable and the negative battery post to prevent modules from resetting and to catch capacitive drains.
5. Disconnect the negative battery cable from the post without breaking the connection of the jumper wire.
6. Connect the tester between negative battery cable and the post. The meter must be capable of reading milliamps and should have a 10 amp capability.
7. Remove the jumper wire.
8. If the draw is found to be excessive, pull fuses from the battery/central junction box one at a time and note the current drop. Do not reinstall the fuses until you are finished testing.
9. Check the wiring schematic in the wiring diagram for any circuits that run from the battery without passing through the battery/central junction box. Disconnect these circuits if the draw is still excessive.

ELECTRONIC MODULE PARASITIC DRAW TEST

1. Repeat the steps of the battery drain testing.
2. Make sure all doors are closed and accessories are off. Without starting the engine, turn the ignition switch to RUN for a moment and then OFF. Wait a few minutes for the illuminated entry lamps to turn off if equipped.
3. Connect the ammeter and read the amperage draw.

The current reading (current drain) should be less than 50 mA (0.05 amp). If the current drain exceeds 50 mA (0.05 amp) after a few minutes, and if this drain did not show in previous tests, the drain is most likely caused by an inoperative electronic component. As in previous tests, remove the fuses from the battery/central junction box one at a time to locate the problem circuit.

SELF-DIAGNOSTIC SYSTEM

Note. All diagnostic tests are written specifically for New Generation Star (NGS) tester. Most generic OBD-II compliant scan tools should be able to perform all test procedures.

RETRIEVING & CLEARING DIAGNOSTIC TROUBLE CODES

For retrieving and clearing DTCs, see SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV in ENGINE PERFORMANCE.

Using NGS tester, perform PCM self-test. Perform appropriate test under SYSTEM TEST in accordance with DTC retrieved. See POWERTRAIN CONTROL MODULE DIAGNOSTIC TROUBLE CODE INDEX table. Codes listed in this table are only for testing covered in this article. For complete DTC listing, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV in ENGINE PERFORMANCE. If no DTCs are retrieved, repair by symptom. See SYMPTOM INDEX table under SYSTEM TESTS.

POWERTRAIN CONTROL MODULE DIAGNOSTIC TROUBLE CODE INDEX

TEST A: BATTERY IS DISCHARGED OR BATTERY VOLTAGE IS LOW

1. Check The Battery Condition Perform Battery Test to determine if the battery can hold a charge and is okay for use. See «BATTERY LOAD TEST»(ref-139561-S01332774352004061100000) or «BATTERY TEST WITH DIGITAL BATTERY ANALYZER»(ref-139561-S42540177362004061100000) under ON-VEHICLE TESTING. Is the battery okay? If yes, go to next step. If no, install new battery. Test the system for normal operation.
2. Check The Generator Output Perform generator tests. See «GENERATOR LOAD TEST»(ref-139561-S28540676852002050100000) and «GENERATOR NO-LOAD TEST»(ref-139561-S37470455162002050100000) under ON-VEHICLE TESTING. Is the generator okay? If yes, go to next step. If no, go to «TEST B: THE CHARGING SYSTEM WARNING INDICATOR IS ON WITH THE ENGINE RUNNING (THE CHARGING SYSTEM VOLTAGE DOES NOT INCREASE)»(ref-139561-S40348315262002050100000) to diagnose the charging system.
3. Check For Current Drains Perform battery drain test. See «PARASITIC DRAW TEST»(ref-139561-S22463893292004061100000) . Are there any excessive current drains? If yes, repair as necessary. Test the system for normal operation. If no, go to next step.
4. Check For Current Drains Which Shut Off When The Battery Is Disconnected Perform electronic module parasitic draw test. See «ELECTRONIC MODULE PARASITIC DRAW TEST»(ref-139561-S22767518072004061100000) . Are there any current drains which shut off when the battery is disconnected? If yes, repair as necessary. Test the system for normal operation. If no, go to «TEST B: THE CHARGING SYSTEM WARNING INDICATOR IS ON WITH THE ENGINE RUNNING (THE CHARGING SYSTEM VOLTAGE DOES NOT INCREASE)»(ref-139561-S40348315262002050100000) to diagnose the charging system.

TEST B: THE CHARGING SYSTEM WARNING INDICATOR IS ON WITH THE ENGINE RUNNING (THE CHARGING SYSTEM VOLTAGE DOES NOT INCREASE)

1. Check Generator B+ Circuit (Black/Orange Wire) Measure the voltage between the generator B+ terminal and ground. (Scheme 1) Is the voltage equal to battery voltage? If yes, go to next step. If no, repair Black/Orange wire. Test the system for normal operation.
2. Check Generator "A" Circuit (Orange/Light Blue Wire) Measure the voltage between the generator connector terminal "A" and ground. (Scheme 2) Is the voltage equal to battery voltage? If yes, go to next step. If no, repair Orange/Blue wire. Test the system for normal operation.
3. Check "I" Circuit (Light Green/Red wire) For An Open With the ignition switch in the RUN position and the engine running, measure the voltage between the generator connector terminal "I" and ground. Is the voltage 8-10 volts? If yes, go to step 5. If no go to next step.
4. Check "I" Circuit (Light Green/Red wire) For Continuity Measure the resistance between the generator connector terminal "I", harness side and the PCM connector "A", terminal No. 8, harness side. (Scheme 3) Is the resistance less than 5 ohms? If yes, install a new PCM. Test the system for normal operation. If no, repair Light Green/Red wire. Test the system for normal operation.
5. Check For Voltage Drop In B+ Circuit (Black/Orange wire) With the engine at 2,000 RPM, turn the headlamps and the rear defroster on and the blower motor to high, measure the voltage drop between the generator connector B+ terminal (Black/Orange wire), component side and positive battery terminal. Is the voltage drop less than 0.5 volt? If yes, install a new generator. Test the system for normal operation. If no, repair high resistance in the B+ circuit. Test the system for normal operation.

Scheme 1

Scheme 2

Scheme 3

TEST C: THE CHARGING SYSTEM OVERCHARGES (BATTERY VOLTAGE IS GREATER THAN 15.5 VOLTS)

1. Check For Voltage Drop In "A" Circuit (Orange/Light Blue wire) With the engine running, turn the headlamps and rear defroster ON and the blower motor on HIGH; measure the voltage drop between the generator connector terminal "A", harness side and positive battery terminal. (Scheme 2) Is the voltage drop less than 0.5 volt? If yes, go to next step. If no, repair the high resistance in the Orange/Light blue wire. Test the system for normal operation.
2. Check Generator & Battery Ground Connections Check the ground connections between the voltage regulator and the generator and the engine, and the battery and the engine. See «WIRING DIAGRAMS»(ref-139561-S00514772402002050100000). Are all ground connections clean and tight? If yes, install a new generator. Test the system for normal operation. If no, repair ground connections as necessary. Test the system for normal operation.

TEST D: THE CHARGING SYSTEM WARNING INDICATOR IS ON WITH THE ENGINE RUNNING AND THE BATTERY INCREASES VOLTAGE

1. Check "I" Circuit (Light Green/Red Wire) For An Open Turn the ignition off. Disconnect generator connector. With the engine running, measure the voltage between the generator terminal "I", harness side and ground. (Scheme 2) Is the voltage 8-10 volts? If yes, go to step 4. If no, go to next step.
2. Check "I" Circuit (Light Green/Red Wire) For Continuity Turn ignition off. Disconnect PCM connector "A". Measure the resistance between the generator connector terminal "I", harness side and the PCM connector "A", terminal No. 8, harness side. (Scheme 3) Is the resistance less than 5 ohms? If yes, go to next step. If no, repair Light Green/ Red wire. Test the system for normal operation.
3. Check "I" Circuit (Light Green/Red Wire) For A Short To Ground Measure the resistance between the generator connector terminal "I", harness side and ground. Is the resistance greater than 10,000 ohms? If yes, install a new PCM. Test the system for normal operation. If no, repair circuit. Test the system for normal operation.
4. Check Generator Integrity Turn ignition off. connect generator connector. Measure the voltage between the generator connector terminal "I" and ground. Is the voltage less than 2 volts? If yes, install a new generator. Test the system for normal operation. If no, see appropriate ANALOG INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT for diagnosis of the instrument cluster.

TEST E: THE CHARGING SYSTEM WARNING INDICATOR IS OFF WITH THE IGNITION SWITCH IN THE RUN POSITION AND THE ENGINE OFF

1. Check The Charging System Warning Indicator Lamp Disconnect generator connector. With the engine off, connect a fused jumper wire (15A) between the generator connector terminal "I" (Light Green/Red wire), harness side and ground. (Scheme 2) Turn ignition on, engine off. Is the charging system warning indicator illuminated? If yes, install a new generator. Test the system for normal operation. If no, see appropriate ANALOG INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT for diagnosis of the instrument cluster.

TEST F: THE CHARGING SYSTEM WARNING INDICATOR FLICKERS OR IS INTERMITTENT

1. Check For Loose Connections Check all generator, battery, and power distribution connections for looseness, corrosion, loose or bent terminals, or loose eyelets. See «WIRING DIAGRAMS»(ref-139561-S00514772402002050100000). Are all connections clean and tight? If yes, go to next step. If no, repair as necessary. Test the system for normal operation.
2. Check Fuse With the engine running, check fuse No. 21 (5A) in central junction box looseness by wiggling the fuse and noting the charging system warning indicator operation. Does the charging system warning indicator flicker? If yes, repair loose fuse connections as necessary. Test the system for normal operation. If no, go to next step.
3. Check "A" Circuit (Orange/Light Blue Wire) Connections Turn ignition off. Connect a fused jumper wire between the generator connector terminal "A", harness side and the positive battery terminal. (Scheme 2) With the engine running, note the charging system warning indicator operation. Does the charging system warning indicator flicker? If yes, install a new generator. Test the system for normal operation. If no, repair loose connection(s) in circuits. Test the system for normal operation.

TEST G: THE GENERATOR IS NOISY

1. Check For Accessory Drive Noise Check the accessory drive belt for damage and correct installation. Check the accessory mounting brackets and generator pulley for looseness or misalignment. Is the accessory drive okay? If yes, go to next step. If no, repair as necessary. Test the system for normal operation.
2. Check Generator Mounting Check the generator mounting for loose bolts or misalignment. Is the generator mounted correctly? If yes, go to next step. If no, repair as necessary. Test the system for normal operation.
3. Check Generator For Electrical Noise Turn ignition off. Disconnect generator connector. With the engine running, using a stethoscope or equivalent listening device, probe the generator. Is the noise still present? If yes, go to next step. If no, install a new generator. Test the system for normal operation.
4. Check Generator For Mechanical Noise With the engine running, use a stethoscope or equivalent listening device to probe the generator area for unusual mechanical noise. Is the generator the noise source? If yes, install a new generator. Test the system for normal operation. If no, diagnose the source of engine noise.

TEST H: RADIO INTERFERENCE

1. With the engine running, tune the radio to a station where the interference is present. Turn ignition off. Disconnect generator connector. Start engine. With the engine running, note any radio interference. Is the interference present with the generator disconnected? If yes, diagnose the in-vehicle entertainment system. If no, install a new generator. Test the system for normal operation.