Hey everyone, new to the forums here. Just got myself a gently used Econoline E-350 7.3 Diesel and was loving it when she ran:





E-350 7.3 Diesel

Recently I have been having some charging issues. It started with it intermittently having a hard time to start, especially when it was warm. I carried a jump box with me and that always seemed to work. Then I noticed the voltmeter on the dash dropping. It went down to the 8 and I was like something is wrong.

Checked the battery voltage, it was at 9.6v. OK, maybe alternator isn't charging. Advance Auto tested the alternator, said it was bad. I replaced alternator. No difference. I pulled the battery and ran it on a conditioner to bring it up to proper voltage. It's now at 12.6v resting. Starts the van no problem. When running though the voltage doesn't increase to 13-14 volts like it should though telling me the alternator isn't doing it's job. Increasing engine RPM actually decreases voltage? Checked all the obvious things like bad grounds but everything seemed clean.

The only thing that was fishy was when I pulled the three way plug from the alternator, one of the pins had corrosion on it. I cleaned it up before installing the new alternator. I didn't do a diode test on the new alternator because I figured it was new, but hey maybe I got a lemon?

Anyway I'm going crazy trying to figure out where the problem is. All fuses are ok. Is there an external regulator or something I should be on the lookout for? Is there anything else that could be causing a non charging issue? The battery was manufactured in 2014 so it's relatively new.

And on a random note my ABS light is now on?

I've searched the forum and can't seem to find anything similar to this, so apologies if it's been asked before. Thanks!

 

I wouldn't leave a parts store with an alternator without having them test it. I've seen too many of them bad out of the box.

 

Hmm guess I know what I'll be doing tomorrow? Any other ideas? Thanks Pikachu.

 

After rereading your post it appears as if you pulled and checked one battery. There's two batteries in your system, one in engine bay and one on the frame rail under the passenger seat.

 

You were certainly right! I thought it was weird that there was only one, but I figured it would be obvious. I figured wrong. Man this thing was tucked up in there. Took three different socket sizes to get it out of there. It looks like they attached the box to the frame at the plant, put the battery in it and then set the body on top of it. Really dumb design. There was no easy way to get in there, even to check the leads.




Anyway, this battery was fine. Actually fairly new and it test 12.6 volts so no issues there. With all the other batteries disconnected, I went to the front leads and tested the voltage and it was 6.7 volts. That would tell me I am loosing voltage somewhere between them, perhaps at a faulty ground? I lost daylight and had to fix my daily driver so I had to shelf it for the night, but I will keep at it and report back.

 

Sounds like you're on the right track and have the problem narrowed down. Good luck.

 

Here are some excerpts that may be of assistance to you.

*NOTE* No charge from alternator...replaced alternator.... Still no charge?

The Sensing & Switching Circuit controls the Alternator Output (on/off). Fuse #6 (Fuse #7 if Dual Alternator Equipped) in the under hood junction box (5 Amp). Connects the circuit to the instrument cluster.

a. Check for continuity from Fuse #6 (LG/R) (Fuse #7 if Dual Alternator Equipped) to the Alternator Plug. If there is no continuity, I have found several:

b. Chafed wires at the valve cover plug.

c. Corrosion on the bottom of the Junction Box

d. And defective Pins on the Alternator Plug.

Any of these will prevent the regulator from closing and thereby show a no charging state. Download "Alternator Circuit.jpg" from Photo's folder for reference.

BATTERIES:

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 .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.

Hope this helps,

Tom

 

Wow Tom that's an amazing and thorough answer! You've certainly given me more to looks for. Still no luck, been at it for a few days now. Here's what I've tackled, in no particular order:

Replaced alternator. No difference. Returned alternator, back to original.

Took original alternator to Advance Auto, bench tested it there. Passed with flying colors. Had them check it again. Passed with flying colors.

Dropped 2nd battery box and checked battery terminals. Cleaned and replaced. Charged battery to 100%.

Cleaned front battery terminals, charged to 100%.

Removed ground cable from battery to block, cleaned and replaced. Applied dielectric grease.

Followed positive wire from front battery to fuse box under hood. Removed all connectors, cleaned and replaced. Checked each fuse under hood, including #6 and #7 with test light on each side, good to go.

Cleaned b+ terminal on back of alternator and ring terminal. Replaced. Fixed crappy insulation to prevent fire down the road.

Put test light on 12v pin from alternator harness, confirmed constant 12v current coming down field wire. Got a pic of it:




Confirmed alternator is properly grounded to block.

Noted on wiring diagram the rectifier is outputting 6v through that little jumper wire, or supposed to be. Not sure what that's about. Scratched head.

Checked voltage on battery with and without truck running. Stays constant at 12.6 volts or so. Increasing engine RPM actually makes current drop. Checked voltage directly out of alternator, reading is the same.

Truck has no problem starting, no hesitation, cranks normal. Runs great (off of battery I am assuming.)

Indicator light on dash comes on and turns off as it should when ignition is turned on.

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I'm going to re-read your post and give it another go. Am I missing anything? This is sucking the fun out of my weekend Thanks in advance for any other info.

 

OK update, not sure what I did but everything seems to be working today? Only thing I can think of is I drove it briefly the night before (I was assuming off of the battery). Maybe something jiggled back in to place? I 'm going to have to keep an eye on it, would hate to be stuck somewhere other than my driveway with it.

Don't you hate when that happens? No explanation... oh well. I'll take it.