With battery ground disconnected and positive connected if i take a voltage tester and touch from battery ground to chassis ground i get 12.52 volts, just what the battery tests,+ to -.

Purchase or make up a tester using a small 12 volt globe and 2 wires. Connect one test-lead to negative ground.
Any exposed metal screw to bodywork will do.
Now, if you want to test which fuse is blown, touch sharpened point of positive test lead to metal tab of fuse on output side, going through each fuse until no voltage is found.
If you have power and want to disconnect it via the fuse:
Connect positive side of tester to car radio's positive on harness.
Pull each fuse one-by-one until no power.

the fuel pump relay has 4 leads. one is positive to battery, one is negative, ground, one is input voltage(on/off), and one is load (to the fuel pump +). Locate a 12 volt dc power source and connect the negative to the relay ground, and the positive to the relay input voltage lead. When 12 volts is applied to the input voltage, you should hear a click of the relay opening- additionally, if you have a multi-tester, you can also check for continuity (resistance, ohmage) by connecting the multi-tester to the 2 other leads. when the input voltage lead receives the 12 volts, you should hear a click AND the multitester should detect continuity in the circuit, and lose continuity when the 12 volt is removed from the input voltage lead.

normally from the negative terminal of the battery to either the chassis,panel part or directly onto the engine

Check the display. Ask a helper to step on the brake pedal while you check the lights from the rear. If no lights appear, check the fuse that connects the brake lights. The owners manual will show the location of the fuse box and which fuse is for the brake lights. Pull out the fuse and look at the wire in the central window. If the wire is broken, replace the fuse. Make sure the new fuse is not blown, and carries the same amperage.
Take note of lights that are out, if any are working. The problem may be cured by replacing the bulb in a brake light that's out. A burned out bulb has a broken filament and a dark brown spot on one side. Check the owners manual for bulb type.
Check the circuit if replacement bulbs and fuses do not restore the lights. Find the wiring diagram in the vehicle assembly manual. The circuit for the brake lights runs from the battery to the fuse, to the pedal switch, to a connection plug, to the lights. The circuit has to be checked with a volt tester at all points.
Check the battery power and the light on your volt tester. Turn the ignition key far enough to activate the electrical systems. Turn on the lights to check for battery power. If the battery has power, ues it to check the volt tester. Put the black lead (the ground) from the volt tester on the negative battery terminal. Briefly touch the red tester light on the positive terminal. The light on the volt tester should flash brightly.
Test the wiring to the fuse. Clip the ground wire to solid metal near the fuse. Touch the light tip to both sides of the fuse. Both should light the tester. If neither side lights, the wire between the battery and fuse is bad. If only one side lights, the fuse is blown.
Test the switch and wiring. Touch the light tip of the tester to both terminals on the brake pedal switch without putting any pressure on the pedal. One should carry power and the other should not. When both show power, the switch is stuck and the brake lights are always on. If neither shows power, the wiring between the fuse and the switch is bad. Now check both switch terminals while the pedal is depressed. Both sides should light the tester. If not, the switch is bad.
Check the connection plug. Unplug the connection and refer to the vehicle manual to identify the brake light wire. Touch the tester light on the brake light wire at the inner socket on the battery side. If the tester lights, the power is flowing to this point. If not, the wire between the plug and the pedal switch is bad.
Check the socket. Plug in the connector plug and remove the bulb. Touch the contact inside the socket. If the tester lights, the socket is good. The socket and wire running to the plug should be replaced if the tester doesn't light.
Check the bulb with the ground wire. The bulb must be in its socket. The ground wire running to the socket should be black or brown. Stab the tester through the insulation. If the tester lights, the bulb is good. Replace the bulb if it doesn't light.
Check the ground wire. Remove some of the insulation around the ground wire. Twist one end of the extra wire around the exposed ground wire. Touch the other end to a solid piece of metal. If the brake light comes on, the ground wire is bad.
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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 www_ropesmor,

This code P0123 is Throttle position sensor circuit high input.

There four basic reasons for this code.

1. An open or short to ground between the TPS (throttle position sensor) and the ECM (Engine control module).
2. A short to battery voltage between TPS and the ECM.
3. A short between the TPS wires.
4. A faulty TPS.

See below for connector diagrams.

First, with scan tool monitor TPS with throttle closed voltage should be
I f you don't have a scan tool, back probe terminal 1with a volt meter to ground and you will see the voltage as outlined above otherwise follow the steps below.


1.Check to see if there is about 5 volts at the TPS; with engine off key on disconnect the TPS back probe the harness side terminal 3 to ground with a volt meter if there is about 5 volts go to step 2 if about 5 volts if not repair the 5 volt circuit.

2. Probe the harness side terminal 2 to chassis ground with a volt meter, if voltage above .02 repair circuit 2 short to voltage. If voltage is .02 volts or below go to step 3.

3. Probe the harness side terminal 1 to ground with volt meter if below .5 volts go to step 4 if not repair short to battery between TSP harness and ECM connector

4 Turn the ignition off and disconnect the ECM connector . With an ohm meter measure the resistance between the ECM (terminal C18) and TPS ground circuit it should be below 1 ohm. Measure the resistance between the ECM (terminal C8) and TPS signal circuit it should be below 1 ohm. If not repair the open circuit.

After faulty circuit is found and repaired clear code and verify repair.







I hope this helps.

Regards,

netvan

Odds are the problem is with the alternator rather than the battery however both are possible. Your local garage can test this for you, usually for free, if you can get the car there. But if you can't and have a set of booster cables and a DC voltage tester ( usually the small cheap ones are sufficient) then the following will work to let you know where the problem lies. Boost charge your battery from another vehicle ( positive to positive, negative to ground or follow the directions in your owners manual) until there's enough voltage in your battery to start your car. Make sure all your lights and accessories are shut off. With the engine on the problem car running disconnect the booster cables from both vehicles. Turn the tester on to DC volts on a range setting closest to but not less than 18 volts. Attach red lead to positive and black to negative on the questionable battery. Have an assistant rev the engine slightly. If the reading on the tester is below 12 volts then your alternator is not putting out enough voltage to charge your battery and it's your alternator that needs replacement. Of course this is assuming all of your main wires are snug and in good condition.

Hello! Either the positive battery connection or the ground connection is resistive (dropping voltage across the cables)...The ground connection being most suspect...If you have a digital multimeter and a wee bit of experience using one these connections can be tested...Set the meter to the lowest dc voltage scale...Place the + probe of the meter on the center of the + battery terminal...The - probe on the other end of the cable at the starter...You must read less than .03 volts...Next, place + probe on the - battery post and the - probe on bare metal of the starter case...You must read less than .05 volts,,,If not the connections need to be removed and cleaned so bare metal touches bare metal...A quick test with meter set on the X10 ohm scale is to measure between the center of the - battery terminal to both chassis and engine block...Both should read a dead short ie...zero ohms...Guru...saailer

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

Get a battery check first and have it charged. Then, switch off all lights, radio, ignition switch. Reconnect the charged battery negative ground first, then, the positive terminal. Find if there's a spark. if it does, then, you must check your electrical wiring since this is grounded. Do not connect the positive terminal. Clear the grounded connection first. If no spark, go ahead. Crank your engine, and let it run at neutral position. And check the voltage that goes out of the alternator, this must be more than 15 volts DC. Then check the voltage output of the regulator which must be 13
to 14 volts DC. However, if you cannot get the right voltage at the
alternator., you have to replace it. Then, you can check the regu-
lator output voltage, and get the right voltage. Get this done,. and
send your e-mail for the result.

if its a standard check the clutch pedal switch if its an auto check the neutral safety switch and check the fuse in the fusebox that says CRANK