When exiting the freeway last Friday morning I noticed my batter icon lit and volt gauge was reading at N of Normal. It's usually at the M. Replaced alternator in parking lot that night to go home but no change. After 5 hours Saturday removing both batteries, topping elector-lite and charging, cleaning battery end of all cables and removing / cleaning post of charge cable from alternator at passenger fender still no change. (Swamped alternators many times doing tests.) With digital meter my batteries were reading 19+ volts on the bench (They are forklift batteries rated at 1000cca @ 0degrees). Charge post of alternator reads 14.5 volts with cable to batteries attached, once removed post reads .5 volts. Took both alternators, new and old, into Advance Auto Sunday. They both bench test as good. Found one 30amp Maxy fuse blown but it's the trailer battery circuit. 50amp Maxy for charging system is fine. Seems I'm not getting a signal to the alternator to induce the field. Alternator is about 32 months old but truck sat for a year, has been back on the road about 8 months. Any help here would be Much Appreciated!

 

I suspect it's one of the Fuseable links hooked to the starter solenoid on the passenger fender. Perhaps the trailer charge system did it...... remove the trailer charge solenoid

 

Thanks again Cuda. Would that solenoid be in the fuse box next to the air filter? I buy passed the fuse-able link in the alternator charge cable long ago. After 3 alternators and two fuse-able links in under two hours I'd had enough. That break down left me less then 20 hours to drive from Grand Rapids MI to New Orleans with a tool trailer in tow.

 

I think you're answering yoru own question...
Did you ever find the reason why those fuse links kept blowing?
There has to be a reason why...

I had the main alternator wire actually break on 2 of my trucks just under the degas bottle. You have to pull the battery and degas bottle out and remove the wire harness going from the alternator to the fender solenoid. There's a bend in the harness and the wires corroded or just plain wore out there or something stupid. I chased the problem like you till I tore into the wires.
A short there would pop that fuse link, I'd imagine.

Good luck.

 

This post here can also be part of your trans issue you
have in another post. You will have to look for the open
or short in the harness now. You have bypassed the link
and made the wire itself the fuse.

.02
Bill

 

Do you think that could be part of the problem?

 

Thank all of you for your replies! Perhaps I'm not being clear. There is NO fuse-able link in the battery charge cable from the stud on the alternator to the relay on the passenger fender. I understand I didn't correct that problem buy the book but it has worked for over 2 years. My problem at this point is the alternator does not produce current. It's been off the truck and bench tested along with the new one, both work fine. And it works if I do the jumper / test in the truck. For some reason it's not receiving signal / power to induce the field. After doing a long search this morning I found the specs for when and how much voltage should be at each wire in the 3-wire plug and will test this asap. Was hoping there was another fuse or link in the harness on the control circuit side rather then pulling the loom apart looking for a broken wire. As to my high battery voltage I don't know 100% if my meter is correct or if this is the result of using HD hilo batteries. Either way again thank all of you for your input. One other FYI. I've used my Edge programmer to check for codes. The only one is "Exhaust back pressure sensor high" or something to that effect. Which I have had for several years. About the same time as I started having EBPV issues.

 

Okay dug out from the Blizzard we had here a week ago. Tested the batteries again they are reading 13.5 volts. Tested the 3-wire plug on the alternator with the key off, key on, and truck running. All tests were from the negative post on the battery. The green wire (drivers side) is 3.88 volts, middle white wire is .04 volts, and white wire (passenger side) is .02 volts. Same reading regardless of key position or truck running. Does anyone know what turns this circuit on? Short of tearing the wiring loom apart what is the next place to check. Have checked all the fuses in the engine compartment fuse box but not in the truck yet. Everything seems to be working all though the wipers and turn signals seem a little slow. Drove a 150 miles on batteries alone last night. Thanks again for the help on this one.

 

Green should read 12v with ign in run and start.
You checked the 5amp fuse in ip box?

Bill

 

Ahhhh............No. What 5amp fuse and is this a stupid question, but what is the ip box? Thank You for your response!

 

A bit of my mistake. The E-series has a fuse.
The f-series does not.
What year is your truck?

The Y/W and BK/O should be 12V from the fuse link.
LG/R is from the ign thru the charge lamp.

IP was instrument panel

Bill

 

Bill,

My truck is a 96 with 220k. I don't have that color scheme at my 3-wire plug. At this point I know what it's not doing. I need to know what is upstream in the system. What controls or sends power to the wire on the drivers side of the plug that should be 12+ / battery voltage with the key on?? The alternator and regulator work. It's NOT getting power / signal. Where does that power come from??? And why would I have 3.8 volts there but not 12? Shorted? Relay somewhere? Some stupid Ford design or hidden fuse?

Duh! Are you telling me there is a fuse-able link in the wire loom? We're NOT talking about the link in the large charge cable coming off the stud on the alternator? Because I DON'T have a fuse-able link in that section anymore. When I jumper the regulator the alternator works. It's NOT getting power from the circuit in the wire loom.

Thanks,
Chuck

 

Less work this way Chuck.

<a href="http://good-times.webshots.com/photo/2030346530103887306TtURGE"><img src="http://inlinethumb33.webshots.com/43744/2030346530103887306S500x500Q85.jpg" alt="charge system"></a>

Bill

 

Thanks Bill,

When I download the diagram I can't open it. I'm not an electrical engineer so it doesn't do me any good on the screen. At this point I'm about to put a switch in the dash straight to the regulator and chalk this one up to more POS Ford Engineering!

Chuck

 

Don't give up now! I am having the same no signal prob 2day with a 97 f250 psd. yesterday i drove truck and charging was intermittent. pulled O'rielly lifetime alt. off- took 2 store -tested bad. they give me another and i installed along with a new 3 wire plug. the old plug showed signs of rust. so i used heatshrink butt connectors. i have backprobed my connections and they pass. my orange blk 4 guage actually runs to the gpr in center of engine. i did unplug ebv actuator because tube needs cleaned. kicking in and out all the time etc, etc. my orange blk wie tests ok for continuity. batteries were @ 13.98 after chrgng but drp 2 12.17 and falling at alt and 12.16 at batt -using batt ground post 4 ground. positive cables(cable) are brand new. i dont like the new 3wire plug- not a true wthrpk- but it seems to test ok for cont. one thing i haven't seen addressed is the bat lamp. mine is not coming at key on. hasn't been for a while either. i- like you feel that no signal voltage is my problem. but i have heard of some fords that would not charge if lamp was burnt out but hav no personal experience with that myself. btw i took new alt back and had it ckd also. if anyone could help us out here it would b great- my hands are about frozen enough 4 the day!