I just install another alternator on 79 mercury capri with a 302 motor and still not having enough volts reading, the positive I disconnected and the vehicle shuts off. I think i have all the wiring hook up right. I just can't believe its the alternator again.

If you have a test light you can check ground and voltage at pump.

If you need further help, reach me via phone at https://www.6ya.com/expert/chris_b82b45c59bcf133d

That should be controlled by the switch and not the motor. I would get both head lights in the same position and start them together by disconnecting battery for 10 seconds and starting back together

Disconnect the Red battery terminal first and then loosen the serpentine belt by moving the tensioner pulley with the correct socket to permit slack enough to dislodge the serpentine belt from any pulley such as the idler pulley or other pulley. Pay close attention of how the belt is routed prior to removing. Remove electrical connections to the alternator. Remove all alternator mounting bolts to remove the alternator. I would recommend a Haynes manual from the parts store on your vehicle. I will help you now and well into the future with all problems that may occur. Be sure you have a fully charged battery at all times as a low battery will cause the internal voltage regulator to over heat and burn up due to the need for more amperage than the alternator can generate.

It's best to relate symptoms to narrow things down. I assume you are still getting a dead battery when trying to start even after replacing the alternator and battery.
Get a volt meter. Harbor freight sells them ridiculously cheap (about $5). Measure the voltage at the battery terminals when the engine is running. If it is at least 13.5 volts to 15 volts then the alternator is charging correctly. If it is 12 volts then the alternator is not charging the battery.

If the alternator checks out ok, then check for things that could be draining the battery when the car is off. Usual suspect is the trunk light. Put your cell phone on video record into the trunk facing the light, then shut the trunk. If the light stays on, its because the switch in the latch mechanism is faulty. WD40 might make it work, or just pull the bulb. Also, check the glove box light the same way. Good luck...Chris

Could you please explain in further detail what is the L wire you're referring to?

Ford Excursion, Expedition, Lincoln Navigator 2000-2005
Starter

• REMOVAL & INSTALLATION
• TESTING & TROUBLESHOOTING

Print

Removal & Installation

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
   
   Negative battery cable
   
2. Raise and safely support the vehicle.
3. Remove or disconnect the following:
   NOTE To disconnect the hard-shell connector from the solenoid S terminal, grasp the plastic shell and pull off; do not pull on the wire. Pull straight off to prevent damage to the connector and S terminal.
   
   
   Starter terminal cover Terminal nut and separate the battery starter cable from the starter motor Solenoid S terminal connector, if equipped with a starter mounted solenoid
   
4. Remove or disconnect the following:
   
   Starter motor retaining bolts Starter motor from the vehicle
   

To install:

1. Install or connect the following:
   
   Starter motor and retaining bolts. Tighten the bolts to 15-20 ft. lbs. (20-27 Nm). Bttery starter cable and a terminal nut to the starter motor. Tighten the terminal nuts to 79 inch lbs. (9 Nm). Slenoid S terminal connector, if equipped with a starter mounted solenoid Sarter solenoid safety cap, if equipped
   
2. Lower the vehicle.
3. Remove or disconnect the following:
   
   Ngative battery cable
   
4. Start the engine several times to check starter motor operation.

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Remove or disconnect the following:
   
   Negative battery cable
   
3. Raise the front of the truck and install jackstands beneath the frame. Firmly apply the parking brake and place blocks in back of the rear wheels.
4. Remove or disconnect the following:
   
   Wiring from the starter motor terminals Starter motor retaining bolts, loosen Starter retaining bolts while supporting the starter motor Starter from the vehicle
   

To install:

1. The installation is the reverse of removal. Tighten the starter retaining bolts to 15-20 ft. lbs. (20-27 Nm)

4.6L, 5.4L & 6.8L Engines

1. Before servicing the vehicle, refer to the precautions section.
2. Disconnect the negative battery cable.
3. Raise and safely support the vehicle.
4. Remove or disconnect the following:
   NOTE To disconnect the hard-shell connector from the solenoid S terminal, grasp the plastic shell and pull off; do not pull on the wire. Pull straight off to prevent damage to the connector and S terminal.
   
   
   Starter terminal cover Terminal nut and separate the battery starter cable from the starter motor Solenoid S terminal connector, if equipped with a starter mounted solenoid
   
5. Remove or disconnect the following:
   
   Starter motor retaining bolts Starter motor from the vehicle
   

To install:

1. Install or connect the following:
   
   Starter motor and retaining bolts. Tighten the bolts to 15-20 ft. lbs. (20-27 Nm). Battery starter cable and a terminal nut to the starter motor. Tighten the terminal nuts to 79 inch lbs. (9 Nm). Solenoid S terminal connector, if equipped with a starter mounted solenoid Starter solenoid safety cap, if equipped
   
2. Lower the vehicle.
3. Connect the negative battery cable.
4. Start the engine several times to check starter motor operation.

6.0L Diesel Engine

1. Before servicing the vehicle, refer to the precautions section.
2. Disconnect the battery ground cable.
3. Remove starter solenoid protective cap.
4. Disconnect the starter motor electrical connections.
5. Remove the bolts and the starter.

To install:

1. Installation is the reverse of the removal procedure. Tighten the starter bolts to 18 ft. lbs. (25 Nm)

7.3L Engine

1. Before servicing the vehicle, refer to the precautions section.
2. Remove or disconnect the following:
   
   Negative battery cable
   
3. Raise the front of the truck and install jackstands beneath the frame. Firmly apply the parking brake and place blocks in back of the rear wheels.
4. Remove or disconnect the following:
   
   Wiring from the starter motor terminals Starter motor retaining bolts, loosen Starter retaining bolts while supporting the starter motor Starter from the vehicle
   

To install:

1. The installation is the reverse of removal. Tighten the starter retaining bolts to 15-20 ft. lbs. (20-27 Nm)

Testing & Troubleshooting

Feed Circuit Test

1. Make sure the battery is fully charged.
2. Disconnect the Inertia Fuel Shutoff (IFS) switch.
3. Connect a remote starter switch between the starter solenoid S-terminal and the battery positive (+) terminal.
4. Connect the Rotunda 73 Digital Multimeter positive lead to the battery positive (+) post. Connect negative lead to the starter solenoid M-terminal.
   
   

   Fig. Motor feed circuit-S-terminal (1), remote starter switch (2), battery (3), Rotunda 73 digital multimeter (4), B-terminal (5), M-terminal (6)
   

5. Engage the remote starter switch. Read and record the voltage. The voltage reading should be 0.5 volt or less.
6. If the voltage reading is 0.5 volt or less, go to the Motor Ground Circuit Component Test.
7. If the voltage reading is greater than 0.5 volt, indicating excessive resistance, move the Rotunda 73 Digital Multimeter negative lead to the starter solenoid B-terminal and repeat the test. If the voltage reading at the B-terminal is lower than 0.5 volt, the concern is either in the connections at the starter solenoid or in the solenoid contacts.
8. Remove the cables from solenoid B-, S- and M-terminals. Clean the cables and connections and reinstall the cables to the correct terminals. Repeat Steps 3 through 6. If the voltage drop reading is still greater than 0.5 volt when checked at the M-terminal or less than 0.5 volt when checked at the B-terminal, the concern is in the solenoid contacts. Install a new starter motor.
9. If the voltage reading taken at the solenoid B-terminal is still greater than 0.5 volt after cleaning the cables and connections at the solenoid, the concern is either in the positive (+) battery cable connection or in the positive battery cable itself.
10. By moving the Rotunda 73 Digital Multimeter negative lead toward the battery and checking each mechanical connection point, the excessive voltage drop can be located. When the high reading disappears, the last mechanical point that was checked is the concern. Repair or install a new connection as required.

Ground Circuit Test
A slow cranking condition can be caused by resistance in the ground or return portion of the cranking circuit. Check the voltage drop in the ground circuit as follows:

1. Disconnect the inertia fuel shutoff switch.
2. Connect a remote starter switch between the starter solenoid S-terminal and the battery positive (+) terminal.
3. Connect the Rotunda 73 Digital Multimeter positive lead to the starter motor housing (the connection must be clean and free of rust or grease). Connect the negative lead to the negative (-) battery terminal.
   
   

   Fig. Motor ground circuit-Rotunda 73 digital multimeter (1), battery (2), S-terminal (3), M-terminal (4), B-terminal (5), remote starter switch (6)
   

4. Engage the remote starter switch and crank the engine. Read and record the voltage reading. The reading should be 0.2 volt or less.
5. If the voltage drop is more than 0.2 volt, clean the negative cable connections at the battery and body connections, and retest.
6. If the voltage drop is greater than 0.2 volt, determine which way the current is flowing in the cable.
7. Connect the Rotunda 73 Digital Multimeter positive lead to the end of the cable nearest battery positive.
8. Connect the multimeter negative lead to the terminal at the other end of the cable.
9. Crank the engine and observe the voltage reading. The voltage reading should be 0.2 volt or lower. If the voltage drop is too high, clean the terminal ends. Retest, and if still high, install a new cable. If the voltage reading is less than 0.2 volt and the engine still cranks slowly, install a new starter motor.

Voltage Drop Test

WARNING When servicing the starter motor or performing other underhood work in the vicinity of the starter motor, be aware that the heavy gauge battery input lead at the starter solenoid is "electrically hot" at all times.

WARNING A protective cap or boot is provided over the battery input terminal on all vehicle lines and must be installed after servicing. Be sure to disconnect the battery ground cable before servicing the starter motor.
Always make the Rotunda 73 Digital Multimeter connections at the component terminal rather than at the wiring end connector. Making a connection at the wiring end connector could result in false readings because the meter will not pick up a high resistance between the wiring connector and the component.

Hello! I would suspect that the alternator isn't supplying a charge to the battery...There is enough current to handle lights, radio etc...But not enough to drive the starter motor...Not necessarily a bad alternator although it may be...Are the battery terminals clean and tight?...If not, clean and tighten...The quickest way to determine the cause is with a volt meter...If you have one, set it to read +12 volts...With the ignition off read across the battery and record reading...Jump start the engine...Remove jumper cables...Take another reading across the battery...It should read 1.8-2.0 volts higher...If not the alternator is defective...

Guru....Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Sound like you have a bad battery, take the battery to an auto parts where they can check it for you.

you might be tightening it too tight or you have a burr on one of your pullies

short or loose connection