How To Replace Ford F-350 Alternator
1994 Ford F-350 Alternator
Alternator Testing,Removal And Installation:
REMOVAL & INSTALLATION
See Figures 1, 2, 3 and 4
Fig. Disengage all wiring harness connections from the alternator
Fig. Once it is unbolted, maneuver the alternator from the engine compartment
Fig. Side terminal alternator
Fig. Fig. 4: Rear terminal alternator
- Disconnect the battery ground cable.
- Remove the adjusting arm bolt.
- Remove the alternator through-bolt. Remove the drive belt from the alternator pulley and lower the alternator.
Some engines are equipped with a ribbed, K-section belt and automatic tensioner. A suitable tool must be made to remove the tension from the tensioner arm. Loosen the idler pulley pivot and adjuster bolts before using the tool..
- Label all of the leads to the alternator so that you can install them correctly and disconnect the leads from the alternator.
- Remove the alternator from the vehicle.
- To install, reverse the above procedure. Observe the following torques:Pivot bolt: 58 ft. lbs. (78 Nm)How To Test Ford F-350 Alternator
Adjusting bolt: 25 ft. lbs. (34 Nm)
Wire terminal nuts: 60-90 inch lbs. (6.8-10.1 Nm)
TESTING
When performing charging system tests, turn off all lights and electrical components. Place the transmission in P (AT) or N (MT) and apply the parking brake.
To ensure accurate meter indications, the battery terminal posts and battery cable clamps must be clean and tight.
WARNING
Do not make jumper wire connections except as instructed. Incorrect jumper wire connections can damage the regulator or fuse links.
Preliminary Inspection
- Make sure the battery cable connections are clean and tight.
- Check all alternator and regulator wiring connections. Make sure all connections are clean and secure.
- Check the alternator belt tension. Adjust, if necessary.
- Check the fuse link between the starter relay and alternator. Replace if burned out.
- Make sure the fuses/fuse links to the alternator are not burned or damaged. This could cause an open circuit or high resistance, resulting in erratic or intermittent charging problems.
- If equipped with heated windshield, make sure the wiring connections to the alternator output control relay are correct and tight.
- If equipped with heated windshield, make sure the connector to the heated windshield module is properly seated and there are no broken wires.
CHARGING SYSTEM INDICATOR LIGHT TEST
- If the charging system indicator light does not come on with the ignition key in the RUN position and the engine not running, check the ignition switch-to-regulator I terminal wiring for an open circuit or burned out charging system indicator light. Replace the light, if necessary.
- If the charging system indicator light does not come on, disconnect the electrical connector at the regulator and connect a jumper wire between the I terminal of the connector and the negative battery cable clamp.
- The charging system indicator light should go on with the ignition switch in the RUN position.
- If the light does not go on, check the light for continuity and replace, if necessary.
- If the light is not burned out, there is an open circuit between the ignition switch and the regulator.
- Check the 500 ohm resistor across the indicator light.
- Connect the negative and positive leads of a voltmeter to the negative and positive battery cable clamps.
- Make sure the ignition switch is in the OFF position and all electrical loads (lights, radio, etc.) are OFF.
- Record the battery voltage shown on the voltmeter; this is the base voltage.
- Connect a suitable tachometer to the engine.
- Start the engine and bring the engine speed to 1500 rpm. With no other electrical loads (doors closed, foot off the brake pedal), the reading on the voltmeter should increase, but no more than 2.5 volts above the base voltage.
The voltage reading should be taken when the voltage stops rising. This may take a few minutes.
- If the voltage increases as in Step 2, perform the Load Test.
- If the voltage continues to rise, perform the Over Voltage Tests.
- If the voltage does not rise to the proper level, perform the Under Voltage Tests.
- With the engine running, turn the blower speed switch to the high speed position and turn the headlights on to high beam.
- Raise the engine speed to approximately 2000 rpm. The voltmeter reading should be a minimum of 0.5 volts above the base voltage. If not, perform the Under Voltage Tests.
If the voltmeter readings in the No-Load Test and Load Test are as specified, the charging system is operating properly. Go to the following tests if one or more of the voltage readings differs, and also check for battery drain.
OVER VOLTAGE TESTS- If the voltmeter reading was more than 2.5 volts above the base voltage in the No-Load Test, connect a jumper wire between the voltage regulator base and the alternator frame or housing. Repeat the No-Load Test.
- If the over voltage condition disappears, check the ground connections on the alternator, regulator and from the engine to the dash panel and to the battery. Clean and securely tighten the connections.
- If the over voltage condition still exists, disconnect the voltage regulator wiring connector from the voltage regulator. Repeat the No-Load Test.
- If the over voltage condition disappears (voltmeter reads base voltage), replace the voltage regulator.
- If the over voltage condition still exists with the voltage regulator wiring connector disconnected, check for a short between circuits A and F in the wiring harness and service, as necessary. Then, reconnect the voltage regulator wiring connector.
- If the voltage reading was not more than 0.5 volts above the base voltage, disconnect the wiring connector from the voltage regulator and connect an ohmmeter from the F terminal of the connector to ground. The ohmmeter should indicate more than 2.4 ohms.
- If the ohmmeter reading is less than 2.4 ohms, service the grounded field circuit in the wiring harness or alternator and repeat the Load Test.
WARNING
Do not replace the voltage regulator before a shorted rotor coil or field circuit has been serviced. Damage to the regulator could result.
- If the ohmmeter reading is more than 2.4 ohms, connect a jumper wire from the A to F terminals of the wiring connector and repeat the Load Test. If the voltmeter now indicates more than 0.5 volts above the base voltage, the regulator or wiring is damaged or worn. Perform the S and ICircuit Tests and service the wiring or regulator, as required.
- If the voltmeter still indicates an under voltage problem, remove the jumper wire from the voltage regulator connector and leave the connector disconnected from the regulator.
- Disconnect the FLD terminal on the alternator and pull back the protective cover from the BAT terminal. Connect a jumper wire between the FLDand BAT terminals and repeat the Load Test.
- If the voltmeter indicates a 0.5 volts or more, increase above base voltage, perform the S and I Circuit Tests and service the wiring or regulator, as indicated.
- If the voltmeter still indicates under voltage, shut the engine OFF and move the positive voltmeter lead to the BAT terminal of the alternator. If the voltmeter now indicates the base voltage, service the alternator. If the voltmeter indicates 0 volts, service the alternator-to-starter relay wire.
- Disconnect the voltage regulator wiring connector and install a jumper wire between the A and F terminals.
- With the engine idling and the negative voltmeter lead connected to the negative battery terminal, connect the positive voltmeter lead to the Sterminal and then to the I terminal of the regulator wiring connector.
- The S circuit voltage reading should be approximately 1 / 2 the I circuit reading. If the voltage readings are correct, remove the jumper wire. Replace the voltage regulator and repeat the Load Test.
- If there is no voltage present, service the faulty wiring circuit. Connect the positive voltmeter lead to the positive battery terminal.
- Remove the jumper wire from the regulator wiring connector and connect the connector to the regulator. Repeat the Load Test
- Make sure the battery is okay.
- Turn on the headlights or any accessory. If the headlights or accessory do not operate, the fuse link is probably burned out.
- On some vehicles there are several fuse links. Proceed as in Step 2 to test other fuse links.
- To test the fuse link that protects the alternator, check for voltage at theBAT terminal of the alternator, using a voltmeter. If there is no voltage, the fuse link is probably burned out.
CHARGING SYSTEM INDICATOR LIGHT TEST
Two conditions can cause the charging system indicator light to come on when your truck is running: no alternator output, caused by a damaged alternator, regulator or wiring, or an over voltage condition, caused by a shorted alternator rotor, regulator or wiring.
In a normally functioning system, the charging system indicator light will be OFF when the ignition switch is in the OFF position, ON when the ignition switch is in the RUN position and the engine not running, and OFF when the ignition switch is in the RUN position and the engine is running.
- If the charging system indicator light does not come on, disconnect the wiring connector from the regulator.
- Connect a jumper wire between the connector I terminal and the negative battery cable clamp.
- Turn the ignition switch to the RUN position, but leave the engine OFF . If the charging system indicator light does not come on, check for a light socket resistor. If there is a resistor, check the contact of the light socket leads to the flexible printed circuit. If they are good, check the indicator light for continuity and replace if burned out. If the light checks out good, perform the Regulator I Circuit Test.
- If the indicator light comes on, remove the jumper wire and reconnect the wiring connector to the regulator. Connect the negative voltmeter lead to the negative battery cable clamp and connect the positive voltmeter lead to the regulator A terminal screw. Battery voltage should be indicated. If battery voltage is not indicated, service the A circuit wiring.
- If battery voltage is indicated, clean and tighten the ground connections to the engine, alternator and regulator. Tighten loose regulator mounting screws to 15-26 inch lbs. (1.7-2.8 Nm).
- Turn the ignition switch to the RUN position with the engine OFF . If the charging system indicator light still does not come on, replace the regulator.
- Connect the negative and positive leads of a voltmeter to the negative and positive battery cable clamps.
- Make sure the ignition switch is in the OFF position and all electrical loads (lights, radio, etc.) are OFF.
- Record the battery voltage shown on the voltmeter; this is the base voltage.
- Connect a suitable tachometer to the engine.
- Start the engine and bring the engine speed to 1500 rpm. With no other electrical loads (doors closed, foot off the brake pedal), the reading on the voltmeter should increase, but no more than 2.5 volts above the base voltage.
The voltage reading should be taken when the voltage stops rising. This may take a few minutes.
- If the voltage increases as in Step 2, perform the Load Test.
- If the voltage continues to rise, perform the Over Voltage Tests.
- If the voltage does not rise to the proper level, perform the Under Voltage Tests.
- With the engine running, turn the blower speed switch to the high speed position and turn the headlights on to high beam.
- Raise the engine speed to approximately 2000 rpm. The voltmeter reading should be a minimum of 0.5 volts above the base voltage. If not, perform the Under Voltage Tests.
If the voltmeter readings in the No-Load Test and Load Test are as specified, the charging system is operating properly. Go to the following tests if one or more of the voltage readings differs, and also check for battery drain.
OVER VOLTAGE TESTSIf the voltmeter reading was more than 2.5 volts above base voltage in the No-Load Test, proceed as follows:
- Turn the ignition switch to the RUN position, but do not start the engine.
- Connect the negative voltmeter lead to the alternator rear housing. Connect the positive voltmeter lead first to the alternator output connection at the starter solenoid and then to the regulator A screw head.
- If there is greater than 0.5 volts difference between the 2 locations, service the A wiring circuit to eliminate the high resistance condition indicated by excessive voltage drop.
- If the over voltage condition still exists, check for loose regulator and alternator grounding screws. Tighten loose regulator grounding screws to 15-26 inch lbs. (1.7-2.8 Nm).
- If the over voltage condition still exists, connect the negative voltmeter lead to the alternator rear housing. With the ignition switch in the OFFposition, connect the positive voltmeter lead first to the regulator A screw head and then to the regulator F screw head. If there are different voltage readings at the 2 screw heads, a malfunctioning grounded brush lead or a grounded rotor coil is indicated; service or replace the entire alternator/regulator unit.
- If the same voltage is obtained at both screw heads in Step 5 and there is no high resistance in the ground of the A+ circuit, replace the regulator.
If the voltmeter reading was not more than 0.5 volts above base voltage, proceed as follows:
- Disconnect the electrical connector from the regulator. Connect an ohmmeter between the regulator A and F terminal screws. The ohmmeter reading should be more than 2.4 ohms. If it is less than 2.4 ohms, the regulator has failed. also check the alternator for a shorted rotor or field circuit. Perform the Load Test after servicing.
WARNING
Do not replace the voltage regulator before a shorted rotor coil or field circuit has been serviced. Damage to the regulator could result.
- If the ohmmeter reading is greater than 2.4 ohms, connect the regulator wiring connector and connect the negative voltmeter lead to the alternator rear housing. Connect the positive voltmeter lead to the regulator Aterminal screw. The voltmeter should indicate battery voltage. If there is no voltage, service the A wiring circuit and then perform the Load Test.
- If the voltmeter indicates battery voltage, connect the negative voltmeter lead to the alternator rear housing. With the ignition switch in the OFFposition, connect the positive voltmeter lead to the regulator F terminal screw. The voltmeter should indicate battery voltage. If there is no voltage, there is an open field circuit in the alternator. Service or replace the alternator, then perform the Load Test after servicing.
- If the voltmeter indicates battery voltage, connect the negative voltmeter lead to the alternator rear housing. Turn the ignition switch to the RUNposition, leaving the engine off, and connect the positive voltmeter lead to the regulator F terminal screw. The voltmeter should read 1.5 volts or less. If more than 1.5 volts is indicated, perform the I circuit tests and service the I circuit if needed. If the I circuit is normal, replace the regulator, if needed, and perform the Load Test after servicing.
- If 1.5 volts or less is indicated, disconnect the alternator wiring connector. Connect a set of 12 gauge jumper wires between the alternator B+terminal blades and the mating wiring connector terminals. Perform the Load Test, but connect the positive voltmeter lead to one of the B+ jumper wire terminals. If the voltage increases more than 0.5 volts above base voltage, service the alternator-to-starter relay wiring. Repeat the Load Test, measuring voltage at the battery cable clamps after servicing.
- If the voltage does not increase more than 0.5 volts above base voltage, connect a jumper wire from the alternator rear housing to the regulator Fterminal. Repeat the Load Test with the positive voltmeter lead connected to one of the B+ jumper wire terminals. If the voltage increases more than 0.5 volts, replace the regulator. If the voltage does not increase more than 0.5 volts, service or replace the alternator.
- Disconnect the wiring connector from the regulator. Connect a jumper wire between the regulator A terminal and the wiring connector A lead and connect a jumper wire between the regulator F screw and the alternator rear housing.
- With the engine idling and the negative voltmeter lead connected to the negative battery terminal, connect the positive voltmeter lead first to the Sterminal and then to the I terminal of the regulator wiring connector.
- The S circuit voltage should be approximately 1 / 2 that of the I circuit. If the voltage readings are correct, remove the jumper wire. Replace the regulator and connect the regulator wiring connector. Perform the Load Test.
- If there is no voltage present, remove the jumper wire and service the faulty wiring circuit or alternator.
- Connect the positive voltmeter lead to the positive battery terminal and connect the wiring connector to the regulator. Repeat the Load Test.
- Make sure the battery is okay .
- Turn on the headlights or any accessory. If the headlights or accessory do not operate, the fuse link is probably burned out.
- On some vehicles there are several fuse links. Proceed as in Step 2 to test other fuse links.
- To test the fuse link that protects the alternator, check for voltage at theBAT terminal of the alternator and A terminal of the regulator, using a voltmeter. If there is no voltage, the fuse link is probably burned out.
In all of the Field Circuit Drain test steps, connect the negative voltmeter lead to the alternator rear housing.
- With the ignition switch in the OFF position, connect the positive voltmeter lead to the regulator F terminal screw. The voltmeter should read battery voltage if the system is operating normally. If less than battery voltage is indicated, go to Step 2.
- Disconnect the wiring connector from the regulator and connect the positive voltmeter lead to the wiring connector I terminal. There should be no voltage indicated. If voltage is indicated, service the I lead from the ignition switch to identify and eliminate the voltage source.
- If there was no voltage indicated in Step 2, connect the positive voltmeter lead to the wiring connector S terminal. No voltage should be indicated. If no voltage is indicated, replace the regulator.
- If there was voltage indicated in Step 3, disconnect the wiring connector from the alternator rectifier connector. Connect the positive voltmeter lead to the regulator wiring connector S terminal. If voltage is indicated, service the S lead to the alternator connector to eliminate the voltage source. If no voltage is indicated, the alternator rectifier assembly is faulty.
BASE VOLTAGE TEST
- Connect the negative and positive leads of a voltmeter to the negative and positive battery cable clamps.
- Make sure the ignition switch is in the OFF position and all electrical loads (lights, radio, etc.) are OFF.
- Record the battery voltage shown on the voltmeter; this is the base voltage.
Turn the headlights ON for 10-15 seconds to remove any surface charge from the battery, then wait until the voltage stabilizes, before performing the base voltage test.
NO-LOAD TEST- Connect a suitable tachometer to the engine.
- Start the engine and bring the engine speed to 1500 rpm. With no other electrical loads (doors closed, foot off the brake pedal), the reading on the voltmeter should increase, but no more than 3 volts above the base voltage.
The voltage reading should be taken when the voltage stops rising. This may take a few minutes.
- If the voltage increases as in Step 2, perform the Load Test.
- If the voltage continues to rise, perform the Over Voltage Tests.
- If the voltage does not rise to the proper level, perform the Under Voltage Tests.
- With the engine running, turn the blower speed switch to the high speed position and turn the headlights on to high beam.
- Raise the engine speed to approximately 2000 rpm. The voltmeter reading should be a minimum of 0.5 volts above the base voltage. If not, perform the Under Voltage Tests.
If the voltmeter readings in the No-Load Test and Load Test are as specified, the charging system is operating properly. Go to the following tests if one or more of the voltage readings differs, and also check for battery drain.
OVER VOLTAGE TESTSIf the voltmeter reading was more than 3 volts above base voltage in the No-Load Test, proceed as follows:
- Turn the ignition switch to the RUN position, but do not start the engine.
- Connect the negative voltmeter lead to ground. Connect the positive voltmeter lead first to the alternator output connection at the starter solenoid (1992) or load distribution point (1993-96) and then to the regulator A screw head.
- If there is greater than 0.5 volts difference between the 2 locations, service the A wiring circuit to eliminate the high resistance condition indicated by excessive voltage drop.
- If the over voltage condition still exists, check for loose regulator and alternator grounding screws. Tighten loose regulator grounding screws to 16-24 inch lbs. (1.7-2.8 Nm).
- If the over voltage condition still exists, connect the negative voltmeter lead to ground. Turn the ignition switch to the OFF position and connect the positive voltmeter lead first to the regulator A screw head and then to the regulator F screw head. If there are different voltage readings at the 2 screw heads, a malfunctioning regulator grounded brush lead or a grounded rotor coil is indicated; replace the regulator/brush set or the entire alternator.
- If the same voltage reading, battery voltage, is obtained at both screw heads in Step 5, then there is no short to ground through the alternator field/brushes. Replace the regulator.
If the voltmeter reading was not more than 0.5 volts above base voltage, proceed as follows:
- Disconnect the wiring connector from the regulator and connect an ohmmeter between the regulator A and F terminal screws. The ohmmeter should read more than 2.4 ohms. If the ohmmeter reads less than 2.4 ohms, check the alternator for shorted rotor to field coil or for shorted brushes. Replace the brush holder or the entire alternator assembly. Perform the Load Test after replacement.
WARNING
Do not replace the regulator if a shorted rotor coil or field circuit has been diagnosed, or regulator damage could result. Replace the alternator assembly.
- If the ohmmeter reading is greater than 2.4 ohms, connect the regulator wiring connector and connect the negative voltmeter lead to ground. Connect the positive voltmeter lead to the regulator A terminal screw; battery voltage should be indicated. If there is no voltage, service the Awiring circuit and then perform the Load Test.
- If battery voltage is indicated in Step 2, connect the negative voltmeter lead to ground. Turn the ignition switch to the OFF position, then connect the positive voltmeter lead to the regulator F terminal screw. Battery voltage should be indicated on the voltmeter. If there is no voltage, replace the alternator and then perform the Load Test.
- If battery voltage is indicated in Step 3, connect the negative voltmeter lead to ground. Turn the ignition switch to the RUN position, but leave the engine OFF . Connect the positive voltmeter lead to the regulator Fterminal screw; the voltmeter reading should be 2 volts or less. If more than 2 volts is indicated, perform the I circuit tests and service the Icircuit, if needed. If the I circuit tests normal, replace the regulator, if needed, then perform the Load Test.
- If 2 volts or less is indicated in Step 4, perform the Load Test, but connect the positive voltmeter lead to the alternator output stud. If the voltage increases more than 0.5 volts above base voltage, service the alternator-to-starter relay (1992) or alternator-to-load distribution point (1993-96) wiring. Repeat the Load Test, measuring the voltage at the battery cable clamps after servicing.
- If the voltage does not increase more than 0.5 volts above base voltage in Step 5, perform the Load Test and measure the voltage drop from the battery to the A terminal of the regulator (regulator connected). If the voltage drop exceeds 0.5 volts, service the wiring from the A terminal to the starter relay (1992) or load distribution point (1993).
- If the voltage drop does not exceed 0.5 volts, connect a jumper wire from the alternator rear housing to the regulator F terminal. Repeat the Load Test with the positive voltmeter lead connected to the alternator output stud. If the voltage increases more than 0.5 volts, replace the regulator. If voltage does not increase more than 0.5 volts, replace the alternator.
- Disconnect the wiring connector from the regulator. Connect a jumper wire from the regulator A terminal to the wiring connector A lead. Connect a jumper wire from the regulator F screw to the alternator rear housing.
- With the engine idling and the negative voltmeter lead connected to ground, connect the positive voltmeter lead first to the S terminal and then to the A terminal of the regulator wiring connector. The S circuit voltage should be approximately 1 / 2 the A circuit voltage. If the voltage readings are normal, remove the jumper wire, replace the regulator and connect the wiring connector. Repeat the Load Test.
- If there is no voltage present, remove the jumper wire and service the damaged or worn wiring circuit or alternator.
- Connect the positive voltmeter lead to the positive battery terminal. Connect the wiring connector to the regulator and repeat the Load Test.
- Make sure the battery is okay .
- Turn on the headlights or any accessory. If the headlights or accessory do not operate, the fuse link is probably burned out.
- On some vehicles there are several fuse links. Proceed as in Step 2 to test other fuse links.
- To test the fuse link that protects the alternator, check for voltage at theBAT terminal of the alternator and A terminal of the regulator, using a voltmeter. If there is no voltage, the fuse link is probably burned out.
In all of the Field Circuit Drain test steps, connect the negative voltmeter lead to the alternator rear housing.
- With the ignition switch in the OFF position, connect the positive voltmeter lead to the regulator F terminal screw. The voltmeter should read battery voltage if the system is operating normally. If less than battery voltage is indicated, go to Step 2.
- Disconnect the wiring connector from the regulator and connect the positive voltmeter lead to the wiring connector I terminal. There should be no voltage indicated. If voltage is indicated, service the I lead from the ignition switch to identify and eliminate the voltage source.
- If there was no voltage indicated in Step 2, connect the positive voltmeter lead to the wiring connector S terminal. No voltage should be indicated. If no voltage is indicated, replace the regulator.
- If there was voltage indicated in Step 3, disconnect the 1-pin S terminal connector. Again, connect the positive voltmeter lead to the regulator wiring connector S terminal. If voltage is indicated, service the S lead wiring to eliminate the voltage source. If no short is found, replace the alternator.
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