Hey everyone,

I'm brand new to this forum and I appreciate all of the advice that I hope to receive. I have a 1999 E350 6.8 motorhome and I am having trouble getting my alternator to charge. Here's what I know as fact:
1. Brand new alternator, bench tested.
2. Battery indicator light on dash NEVER comes on, even when the RV is initially started.
3. All fuses are good, continuity tests done on each.
4. Batter indicator light on dash is brand new, just replaced all instrument cluster light bulbs.
5. Continuity is good on positive wire leading to the alternator from the battery.
6. Green/red wire on the alternator harness does not have any voltage when key is in ignition or when RV is on (I think this is my problem from what I've read).
7. All belts are appropriately tight and the alternator pulley is spinning when the engine is running.

Questions I have and can't find the answers to:
1. Is the instrument cluster battery indicator light in circuit with the alternator? Does it provide the voltage tickle needed for the alternator to engage?
2. Is there a hidden fuse that I can't seem to find that is hindering my alternator from producing a charge?

Thank you to all who take the time to help. I'm at the end of my rope with this one and I'm trying to avoid throwing parts at it to figure this issue out.

-Jake
San Diego, CA

 

Hey there.
1. Have you checked continuity with a multI meter the ends of the battery cable and all wires leading to and from the alternator harness.
2. Does your alternator harness have 3 wires? If so, one of the thin ones is for the battery light
3. Does your battery test good, and also, with a multimeter set to amps and placed between the posititve terminal and batt cable...do you see any signs of unusual draw when key off?.

 

Seems possibly relevant.....

​​​​​​https://www.ford-trucks.com/forums/1152957-1999-f250-super-duty-not-charging.html

 

Thanks so much for the reply.
1. Yes, ground and positive battery have continuity. Yes, all wires from the alternator have continuity.
2. 3 wires. I've read that the green/red wire is for the battery light. Has continuity all the way to the battery light on the instrument panel.
3. Battery tests great at 12.4v and is less than a year old. I'll check the amps loss tomorrow when it's not raining.

Thanks again!
-Jake

 

I attached a schematic for the 2001 e-series, and while it's not for the '99, it should be at least similar.

There are a lot of fusible links, I'd check those before going anywhere else.

 

The 01 SD with a diesel is quite different from the 99 F53 gasser's charging system. It really shouldn't be used.

Here''s the correct diagram:



Go check fuse F9 in the engine compartment fuse box. If there's no power on the LG/R wire at the alternator, it won't charge as the I circuit is what turns on the voltage regulator.

 

Which is why, if you look at the image I posted VERY CAREFULLY - it says "Diesel w/Single Generator, Gasoline

Also, OP says it's an E350 RV. The image I posted is from the E-series EVTM for 2001.

 

F9 fuse is good. Continuity tested with multimeter. Does voltage go onto the alternator or out of the alternator via the LG/R I wire?

 

Art is correct and has provided the correct drawing. I saw the word "motorhome" (been looking at used ones lately) and jumped to the F53 and missed the E350 reference. Sorry about that!

With that in mind, the correct fuse to check is fuse F14 under the dash which should be HOT IN START OR RUN. The "I" or "Ignition" terminal tells the regulator to turn on when the switch is in the correct position. When the ignition is in START or RUN but the engine isn't running, the regulator also uses this line to provide a ground for the charge lamp. When the alternator starts putting out voltage, the voltage on this terminal rises to the output voltage and the lamp goes out (no current flowing through it).

Sorry about the mis-direction...

 

I just pulled fuse 14 from under the dash and it has continuity, and had 0v with key off and 12.49 with key on. Any other ideas? I really want to fix this my self so I can use the otherwise repair money for gas for this beast 👍I have power at the fuse box, but dash battery light never illuminates and my I wire connecting to the alternator reads 0v with key on and engine on. Thanks.

Jake

 

Check for continuity between the two points (fuse F14 load side and the I connection). You may have a wire broken inside the insulation, probably near the alternator connection.

 

First off, thank you to all who helped with their ideas about this non charging issue. I had the instrument cluster off for a couple of days and replaced all of my dash lights, checked continuity on all wires and on the back of the instrument cluster. By God's grace, I just so happened to look at the I wire (lg/r) and the prong that connected it to the instrument cluster. The I wire was the only prong that was not sitting level. I bent it up to make better contact and boom... Battery light is now on with key on and alternator is now putting out 14.5 v. I'm so pumped to have saved so much money by doing this with everyone's help. What a great first experience on this site. Thank you all again!

Jake

 

Glad you got it solved, and thanks for coming back and saying so for someone in the future. Once you said you had continuity, it never occurred to me the connection at the cluster could be a weak link. This is one of those things a parts changer type mechanic would have been glad to rack up a bill of failed attempts and never solved the issue.
Welcome to the forum.

 

Jake, congratulations on fixing it yourself

And THANKS for reporting back and letting us know what it was.

Enjoy your V10 - it's BSEG time