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That Guy
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19 Posts
Discussion Starter #1
Hi Guys, so I am having issues where the truck isn't charging. I've had issues in the past (last year) that ended up being a broken ground lug that bolted to the frame. I fixed that and it has been great for a long while. Recently, the alternator started charging only after the truck was revved up but It didn't bother me too much. I eventually replaced that alternator with a new (reman FORD) unit. The plug was now on the bottom. It ran well for a while, but started to get funny and quit charging. I swapped the old one back and it would always charge after revved up as it used to. Well that one was starting to die (bearings letting go) so I put the new back on. I found that the issue had been the connector / pigtail because if i would hold it in one spot it would charge and not if I let go. COOL FIXED RIGHT? No. So that next night driving home (headlights / ac on) it was doing great then all of a sudden quit charging again. Turned out that I had a battery go bad. SO i warrantied out 2 NEW batteries, and another Ford Alternator (plug on top this time) just in case the battery took out the innards or voltage regulator of that one.

Everything was great for 2 days then it all quit again. this time I'm stumped.


TL;DR New alternator, 2 New batteries, New pigtail/connector. NO Charge

The real pisser is that i found out it quit at 3am when I had a trailer hooked up and was about to leave on a trip. Charged all that previous day. Parked it, Not charging that morning.

I ruled out the new alt being bad because I snagged an alt off of another truck that was known good, and it didn't charge it either.



Anywho the "I" circuit is feeding the connector from the cluster the signal voltage (IIRC it was between 3 and 8 or 9 volts) depending on KOER or KOEO But as soon as the connector is plugged into the alternator it drops to .004 volts Unplug it and it jumps back to normal signal voltage.
The other wire always has battery voltage like it should. What would cause this? It does this with 3 different alternators. Including the one that runs great on the other truck.


My battery light on the dash NEVER lights up. Even when i first key on. I checked the bulb and all fuses related to the cluster. All good.

If you have any ideas please throw 'em my way. Thanks in advance!
 

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Master BS'er
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5,931 Posts
Is the system voltage ever getting low? Does the charge light prove out when you turn the key on? And how many wires to the alternator? What's the year make and model?

What I'm thinking is that this could very well be normal operation. The only thing that strikes me as unusual is the one wire that's either 3, 8 or 9. That's weird, but anyway some systems, especially two wire alternators it's perfectly normal for the system voltage to not be a steady 14v like the old days.
 

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That Guy
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19 Posts
Discussion Starter #4
Is the system voltage ever getting low? Does the charge light prove out when you turn the key on? And how many wires to the alternator? What's the year make and model?

What I'm thinking is that this could very well be normal operation. The only thing that strikes me as unusual is the one wire that's either 3, 8 or 9. That's weird, but anyway some systems, especially two wire alternators it's perfectly normal for the system voltage to not be a steady 14v like the old days.
Oops, just saw the light never comes on. Even at key on. So now you need the correct diagram for that truck.

2004 6.0 single alt system
I have diagrams, I believe that the 3-9 volt range is correct in operation it’s just that when it is actually plugged into the alternator it loses voltage. I’m not sure if it shorts to ground through the alternator or what.

When it did work voltage was around 14.1 at the terminal and 13.3 in my SCT monitor inside the cab.

Now it’s just battery voltage. As the batteries die (truck running off batteries) the voltage drops. If I unhook batteries while running truck dies
 

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CAT lover
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602 Posts
Just a thought, but have you checked your grounds on the engine block? maybe try running a temporary ground cable from the battery right to the alternator bolt to rule out any question of bad ground.

Stupid question... Are there fusable links in the charging wire? Could they be cooked?
 

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That Guy
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19 Posts
Discussion Starter #6
Just a thought, but have you checked your grounds on the engine block? maybe try running a temporary ground cable from the battery right to the alternator bolt to rule out any question of bad ground.

Stupid question... Are there fusable links in the charging wire? Could they be cooked?


The grounds to the block are solid. At least the one in the front near the tranny filter. I re did that one not long ago, and it has been checked since.

I'll double check my diagram, but i Think 2 out of the 3 alt wires have fusable links but they are still getting voltage, so I don't think thats the issue. I may ohm them out when i get a minute.

I really like the idea of adding a group to the alternator body. I didn't think of that. That would definitely rule out a bad ground. Thank you!
 

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Administrator
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32,949 Posts
the lack of the alt light at key on is going to be a key clue to your issue

there is a way to bypass the charge circuit for testing using the wires at the back of the alternator
 

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That Guy
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19 Posts
Discussion Starter #8
the lack of the alt light at key on is going to be a key clue to your issue

there is a way to bypass the charge circuit for testing using the wires at the back of the alternator
Do you happen to have any more information on the process for this?






Here is some more detail Just in case.

The truck was loaded for a trip friday morning 3 am
I was so pissed that I had to borrow a truck at 5 am and reload that I just let the truck sit until this Thursday afternoon (yesterday)

I came home from work and fired her up.
CHARGING

13.6 at post on alternator
13.1-13.3 on SCT Monitor
I also took temperature readings, just in case. I compared them to what I've read and they seem normal.


I turned AC on max got
13.6 Post
12.6 SCT

Shut truck off for 1 minute and re started

No load
13.6 POST Now (was 13.8 with no load previous fire up)
13.0-13.12

AC ON MAX
13.59 Post
SCT 12.6-12.8

AT this point the pigtail to the alt has
13.36v t the orange wire
12.8 at green wire (I circuit)

I then did some more testing with shutting the truck off, letting it sit, running again, adding lights for more load, etc.

I can post that all up if asked for.

I took the truck to dinner. Drive with ac and lights on. got fuel. all was good.


UNTIL THE NEXT MORNING
I fired it up to go to work ant it just would not charge.
Let run long enough for Glow plugs timer to quit
revved it up in case it just wasn't self-exciting
nothing

Post has 12.35
SCT had 12.12
Orange wire had battery voltage 12.35 or so
Green wire showed 0-0.001

SO what would make the I circuit want to sometimes work and sometimes not?
It doesn't seem like a connection issue because i drove it. it charged fine, and was charging when parked. Literally did nothing to the truck.

Thanks guys
 

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Master BS'er
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5,931 Posts
Gotta have a diagram bro. I'll see if I can find one.

He's talking about bypassing the regulator, or pcm, and full Fielding the alternator. You jump battery voltage straight to the field winding, then check the output. It's a quick and dirty test of what the alt is capable of putting out. You could try it, but I'm not sure it's gonna help much this time. It seems to be a control issue.
 

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Master BS'er
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5,931 Posts
So we've gotta have the exact model of your truck. Systems will be very different from model to model, even in the same make and year.

I've seen an f350 xlt that had an internal regulator and a lariat or whatever that had a two wire system with the regulator inside the pcm. All from the same year, so the details matter on this one.
 

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That Guy
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19 Posts
Discussion Starter #11
Gotta have a diagram bro. I'll see if I can find one.

He's talking about bypassing the regulator, or pcm, and full Fielding the alternator. You jump battery voltage straight to the field winding, then check the output. It's a quick and dirty test of what the alt is capable of putting out. You could try it, but I'm not sure it's gonna help much this time. It seems to be a control issue.
So we've gotta have the exact model of your truck. Systems will be very different from model to model, even in the same make and year.

I've seen an f350 xlt that had an internal regulator and a lariat or whatever that had a two wire system with the regulator inside the pcm. All from the same year, so the details matter on this one.

Okay got ya. Yes i agree with control issue. Its just never consistent.

Truck is 2004 Lariat F350 Supercab Longbed SRW
Single Alternator system with 2 wire control then the B+ post


I have access to all data so I can see diagrams but it does not go as detailed as model specific.
 

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Master BS'er
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5,931 Posts
Perfect. All data is all you'll need. If there isn't two different diagrams then there isn't two systems. Usually anyway, all data is pretty good.

Anyway, if there is no voltage on the green/red wire, that's the problem. Chase it back untill you find power. Looks like it comes from the cluster. Make sure the power isn't dropping out on the red/yellow wire at the cluster. If it's not, and there's no power at the green wire then the cluster is bad. You can also ohms test the green wire and check it that way if you want but resistance can really bite you if you're not careful. Especially on an intermittent problem like this.

Sent from my SM-G950U using Tapatalk
 

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That Guy
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19 Posts
Discussion Starter #13
Perfect. All data is all you'll need. If there isn't two different diagrams then there isn't two systems. Usually anyway, all data is pretty good.

Anyway, if there is no voltage on the green/red wire, that's the problem. Chase it back untill you find power. Looks like it comes from the cluster. Make sure the power isn't dropping out on the red/yellow wire at the cluster. If it's not, and there's no power at the green wire then the cluster is bad. You can also ohms test the green wire and check it that way if you want but resistance can really bite you if you're not careful. Especially on an intermittent problem like this.

Sent from my SM-G950U using Tapatalk
It basically gives me 1 alt system/ 2 alt system / gas truck (externally regulated)

I'm gong to dig in this weekend again. I had ohm'd out the alternator plug to the first harness connection.Was good I forget the connector number this second i believe was pin 6 and it was good to there. I've read threads where people had a dual alternator delete plug. Basically a loop and all-data shows that connector but my truck didn't have it (at least not where i saw photos of others trucks having it.)

But anyway from the plug where i stopped my resistance check it goes though 1 or 2 more connectors, then the firewall to the cluster i believe. Bad thing is yesterday I was going to try and get some tracing done and it was working. I can't fix it when its working.

If the power dropped at the red/yellow wire at the cluster would I lose all cluster functions? Any other symptoms? I have no cluster issues at all other than this.

Thank you for your time!
 

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Master BS'er
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5,931 Posts
Don't know if other functions would stop or not. You would need to look at the diagram for the cluster and see what that fuse feeds if anything else. Also that would tell you if the signal gest through the bulb or is separate. I'm guessing it's separate, but I don't know that.

Look up the cluster circuit for a better answer on that.

Sent from my SM-G950U using Tapatalk
 

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That Guy
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19 Posts
Discussion Starter #15
Don't know if other functions would stop or not. You would need to look at the diagram for the cluster and see what that fuse feeds if anything else. Also that would tell you if the signal gest through the bulb or is separate. I'm guessing it's separate, but I don't know that.

Look up the cluster circuit for a better answer on that.

Sent from my SM-G950U using Tapatalk
From what I can find in alldata it shows the cluster as a device and doesn't get into specific of the diagrams inside of itself, unless I'm missing it.
I wonder if this is all caused by like a broken solder joint in the cluster kinda low how the overhead computers are known for.

I'm going to try and trace the wire all the way from the alt to the cluster tomorrow and see what I can find.
Some of the diagrams for connectors are a little funny but I think i can manage.


If you remember I said that this morning I fired her up to drive to work and it wasn't charging.
I just got home and fired her up and shes charging good. Literally the only change was the time of day.

If I find anything, or have any issues, ill post them up,. Thank you!
 

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Master BS'er
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5,931 Posts
I'm kinda thinking it's an issue inside the cluster too. What you're gonna have to do is get to the green wire at the cluster itself and see if there is a signal coming out or not. Course, you'll have to catch it when it's acting up.

If there's 12v at the cluster but not the alt, the wire is bad. If power is coming into the cluster but not out, the cluster is bad. Smacking it a bit might get the problem to show up more easily. If that doesn't work, don't smack it harder though.

Sent from my SM-G950U using Tapatalk
 

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That Guy
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19 Posts
Discussion Starter #17
So this weekend the truck charged and I drove it all weekend with no issues.Ill admit i didn't start it as early as I do for work days

Monday morning same old ####, not charging, I got home from work Monday 530pm or so and it fired up and charged fine.

Tuesday morning I decided to say f it and drive it to work not charging because I needed to use the truck. I drove 15 miles traffic with it discharging. Maybe 30-45 minutes. I parked the truck and had to move it 1.5 hours later and it didn't charge then either. at the end of the work day 7 hours 45 minutes later ( i timed it for some reason) I started it to drive it home and I revved it up and it began charging. It almost like it just does not like to charge in the morning Or could it maybe be moisture related? Like something to do with the morning dew?

Wednesday Morning same thing. I drove it to work discharging, fired it up now (lunch time) charging good.
Maybe sitting in the florida sun heats something up enough to contact?
Whats weird though is that once i keep driving it even if i shut it off and come back lets say after a movie or something even at night when its cool and no sun it'll still charge again too.

I haven't yet resistance checked from the cluster to the alternator. I'm going to set up to do that saturday morning when i "know" it won't charge in the morning and then wait half a day and check it when it gets warm enough or dry enough or whatever to work.

tapping / smacking on the cluster changes nothing at any time


I'd like to add that the truck isn't some beater work truck where it has like water leaks to the cab and stuff. The truck is in good shape.


Also, if i did throw a used cluster at it, would any 04 cluster work? even from an e series?
 

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That Guy
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19 Posts
Discussion Starter #18
I'm becoming more sure this is temperature dependent. What I said yesterday about driving at night proved false. I drove long enough at night last night (no sun/ac on) for what I'm guessing is the interior to cool enough enough to lose contact. I put a temperature gauge in the truck this morning and once the interior reached around 100F and it charged when I fired it up. (still no charging in the morning)



Is there anything i need to know about before I buy another cluster?

I'm going to disassemble this one first and see if I can find anything, but I'm not hopeful.

Thank You all again so much
 
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