Hi I have a 2002 7.3. When I star unit after being charged my voltage reads 11.9 on edge display truck runs good no issues. I leave it over night and come back to start it is reading 9.9 and will not start.

I used multi meter to check drain it is.60 I dint think that is to bad.
When driving I am reading 14.1 volts.

Thoughts on wher to start I have new battery 6 moths ago.

Thanks in advance

 

This is an indication of failing Battery (or Batteries). Both batteries need to be load tested independent of the other, Specific Gravity (SG) recorded as well as topped off (both Fluid and Charged).

11.9vdc No Load Battery Voltage is not good at all. Anything less than 10.5vdc will drop the CMP out of the PCM and the vehicle will NOT start.

.60 = What you're saying is 600mV draw.

You replaced "I have new battery 6 moths ago". Was this one or both? Ours should always be replaced as a set (2).

You need to begin a troubleshooting process to identify the issue.

Tools: DVOM, Carbon Pile Tester or Similar Device, Hydrometer.

Charging system problems often come to you as a "no-start" complaint. The battery will have discharged and the starter won't crank the engine.

The first step is to test the battery and charge it if necessary.

No-Load Test:

Voltage Percent Charge

12.60V - 12.72V 100%
12.45V - 12.71V 75%
12.30V - 12.44 V 50%
12.15V - 12.29V 25%
(Readings obtained at 80°F)

STARTER MOTOR — LOAD TEST

NOTE: The batteries must be fully charged before performing a starter load test.

1. Set the parking brake and shift the transmission into the NEUTRAL position.

2. Remove Fuse 17 from the engine compartment fuse box.

3. Connect the Alternator, Regulator, Battery and Starter Tester (ARBST). Follow the manufacturers supplied instructions.

4. Connect a remote starter switch across the starter relay Terminal and the battery positive terminal post.

5. Turn the ignition switch to the RUN position.

6. Crank the engine and record the voltmeter reading.

7. Turn the carbon pile control **** until the voltmeter indicates the same reading recorded during cranking the engine. Record the ammeter reading.

8. Compare the ammeter reading with specifications.

STARTER MOTOR — MOTOR FEED CIRCUIT VOLTAGE DROP TEST (7.3L)

1. This test is performed to determine if slow cranking is caused by high resistance in the starter motor circuit wiring.

2. The voltage drop test can only be performed with the starter motor on the vehicle.

3. Disconnect the wiring from the fuel shutoff solenoid.

4. Connect the positive lead of the 73 Digital Multimeter to the battery positive (+) post, and the negative lead to the starter solenoid Terminal.

5. Connect a remote starter switch between the starter solenoid Terminal and the positive battery terminal post.

6. Press the remote starter switch and record the voltage reading.

7. The voltage reading should be 0.5 volt or less. A reading higher than
0.5 volt indicates high resistance.

8. Repeat the test on the starter solenoid B-terminal.

9. If the readings are higher than 0.5 volt, remove the wiring from the starter solenoid.

10. Clean and inspect each wire connector and the starter solenoid terminals.

11. Install the wires onto the starter solenoid and retest.

12. If the reading at the starter solenoid M-terminal is still higher than 0.5 volt or the reading at the B-terminal is lower, carry out the Starter Solenoid Component Test. If no change is noted, install a new positive battery cable lead.

STARTER MOTOR — MOTOR GROUND CIRCUIT VOLTAGE DROP TEST (7.3L)

NOTE: A slow cranking condition can also be caused by high resistance in the ground circuit.

1. Disconnect the wiring from the fuel shutoff solenoid.

2. Connect the Digital Volt-Ohmmeter positive lead to the starter motor housing.

3. Connect the Digital Volt-Ohmmeter negative lead to the battery negative (-) terminal.

4. Connect a remote starter switch between the starter solenoid Terminal and the positive battery terminal post.

5. Press the remote starter switch and record the voltage reading.

6. The voltage reading should be 0.2 volt or less. If the voltage reading is higher, remove and clean the negative cable connections at the battery, starter motor and the body.

7. Retest the system. If readings are still higher than 0.2 volt, test each individual negative cable.

STARTER SOLENOID (7.3L)

1. Disconnect the battery negative cable.

2. Using the Digital Multimeter, check the windings of the solenoid as follows:

a. Measure the resistance between the starter motor ground terminal and the solenoid case. The resistance reading should be approximately 0.95 ohms.

b. An extremely high resistance reading indicates a break or fault in winding continuity.

c. A very low resistance reading indicates a short or ground in the winding circuit.

*Either condition is cause for installation of a new solenoid assembly.

RIPPLE VONTAGE:

1. Ripple Voltage Ripple voltage or (AC voltage) can be measured by switching your DMM to AC and connecting the black lead to a good ground and the red lead to the "BAT" terminal on the back of the alternator, (not at the battery).

2. A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged alternator diodes.

ALTERNATOR LEAKAGE TEST:

Alternator Leakage Current to check alternator diode leakage, connect the Multimeter in series with the alternator output terminal when the car is not running. Leakage current should be a couple of milliamps at most; more often, it will be on the order of 0.5 milliamps. Use care when disconnecting the alternator output wire; make sure the battery is disconnected first.

Using a DMM/High-Voltage Clamp (1000+ AMPS) the Starter should be tested on the Passengers (+) Battery Cable, between the cable connection on the battery and the starter itself. It should NOT exceed 721 AMPS.