400 Charging System Not Functioning - What else could the problem be?
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From: Oregon
I ended up running to Radioshack and picking up a decent DMM for $29.99. I checked the battery, and it came out at 12.58V. When the truck was running, it went to 12.46V. So there's no charging system (I'm shocked 
).
I unhooked the ground cable, and tested with all the fuses in (10A range), it read -0.06 Took all the fuses out, still read -0.06. This is with the trailer brakes and the radio disconnected.
I'm not sure what all this means, as I'm lost when it comes to auto-electrical...
Where else should I start looking for problems?
Well, first things first, I need to get my charging system fuctioning... What should I be testing (and how)? Since, as I've stated (plenty of times
) before, new alternator, solenoid and VR (amongst other parts), so what should I be checking towards wiring and all that?
).I unhooked the ground cable, and tested with all the fuses in (10A range), it read -0.06 Took all the fuses out, still read -0.06. This is with the trailer brakes and the radio disconnected.
I'm not sure what all this means, as I'm lost when it comes to auto-electrical...
Where else should I start looking for problems?
Well, first things first, I need to get my charging system fuctioning... What should I be testing (and how)? Since, as I've stated (plenty of times
) before, new alternator, solenoid and VR (amongst other parts), so what should I be checking towards wiring and all that?
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From: Virginia
Yes, you are not charging. 1st thing to do is take your new meter, put the neg lead on the neg of the battery, and put the + lead on the large output wire on the alternator. You should read battery voltage. If you don't, then follow the large lead from the alternator along in the harness, and somewhere along the way you should run into a colored rubber thing in the wire. This is a fusible link, and is probably blown out if you don't have battery voltage on the output wire of the alt.
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Thanks Franklin2, just tried your suggestion. Output on the ALT reads the battery voltage, so that's not the problem.
There's no power coming out of the white wire with a black stripe either, which appears to go to the electronic choke. I had the motor running and used a test light for that. So no power output whatsoever from the ALT.
What should I be looking for next?
Also, there are two wires welded to the ALT-Solenoid wire, one is a thick black wire with a yellow stripe, that seems to run into the cab (and has power when the motor is running) and one is a smaller yellow wire with a black stripe that runs into the voltage regulator. What is the function of these two, and could they somehow be connected to the problem?
EDIT: Another thing, if I have a bad ground and it's sucking power, would this screw up the ground my voltage regulator has to the body, either burning it up or just causing it to not work?
There's no power coming out of the white wire with a black stripe either, which appears to go to the electronic choke. I had the motor running and used a test light for that. So no power output whatsoever from the ALT.
What should I be looking for next?
Also, there are two wires welded to the ALT-Solenoid wire, one is a thick black wire with a yellow stripe, that seems to run into the cab (and has power when the motor is running) and one is a smaller yellow wire with a black stripe that runs into the voltage regulator. What is the function of these two, and could they somehow be connected to the problem?
EDIT: Another thing, if I have a bad ground and it's sucking power, would this screw up the ground my voltage regulator has to the body, either burning it up or just causing it to not work?
Last edited by ihateminimumwage; Apr 25, 2007 at 03:52 PM.
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Originally Posted by ihateminimumwage
if I have a bad ground and it's sucking power, would this screw up the ground my voltage regulator has to the body, either burning it up or just causing it to not work?
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From: Virginia
The next thing I would do is take a scrap piece of wire, disconnect the wire on the "f" terminal of the alternator, and put your scrap piece of wire on that terminal. Get the meter set up to read battery voltage. Get the engine running, and watch the battery voltage as you take the other end of the "f" wire and touch it to the battery + terminal. When you touch the wire, the alternator should go into full charge if it's working. You should see the battery voltage jump way up, and you may hear the alternator start making a whining noise.
This will tell us if the alternator is in working condition or not.
This will tell us if the alternator is in working condition or not.
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From: Oregon
If I have a hot wire touching a ground somewhere in the system, would it be giving me the -.06 reading? The negative mark in front of it is what I'm wondering about.
Also, would anything else obviously be screwing up because of the lack of a full ground? Battery to engine ground seems good, no problems with startup or anything.
I also totally forgot to mention, when I first replaced my alternator and voltage regulator, there was a slight burning smell in the cab. Couldn't smell it from the engine compartment, and my passenger couldn't smell it (but he does smoke a lot, so that's not saying much). I got home that night and it seemed to be coming from my side around the instrument cluster area. I just pulled my cluster off, and can't see anything specifically damaged, but would anyone have an idea of what might have been burning up in there?
Also, would anything else obviously be screwing up because of the lack of a full ground? Battery to engine ground seems good, no problems with startup or anything.
I also totally forgot to mention, when I first replaced my alternator and voltage regulator, there was a slight burning smell in the cab. Couldn't smell it from the engine compartment, and my passenger couldn't smell it (but he does smoke a lot, so that's not saying much). I got home that night and it seemed to be coming from my side around the instrument cluster area. I just pulled my cluster off, and can't see anything specifically damaged, but would anyone have an idea of what might have been burning up in there?
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From: Oregon
Originally Posted by Franklin2
The next thing I would do is take a scrap piece of wire, disconnect the wire on the "f" terminal of the alternator, and put your scrap piece of wire on that terminal. Get the meter set up to read battery voltage. Get the engine running, and watch the battery voltage as you take the other end of the "f" wire and touch it to the battery + terminal. When you touch the wire, the alternator should go into full charge if it's working. You should see the battery voltage jump way up, and you may hear the alternator start making a whining noise.
This will tell us if the alternator is in working condition or not.
This will tell us if the alternator is in working condition or not.
Yeah, alternator works! With the jumper, my battery was reading at about 15.8 at low idle.Progress!
Alright... What next?
EDIT: Used a circuit tester, and the yellow wire from the voltage regulator to the solenoid is okay, and the green/red wire to the ignition switch has power when I put the key in the power position. So would this mean my VR isn't working (again)?
Last edited by ihateminimumwage; Apr 25, 2007 at 07:08 PM.
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Glad to see Dave helping you! He is much better at talking people thru electrical problems than I am.
He is much better at talking people thru electrical problems than I am.
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From: Virginia
Ok. The alternator works.
You are getting 12 volts from the green/red to the "s" terminal(there are two different ways this could be wired from the factory, let me know if the green red is not hooked to the "s" but hooked to the "i" terminal).
You said the yellow wire, which is hooked to the "a" is good. You should have 12 volts on the "a" terminal of the regulator.
One more check. Take your voltmeter, and put the + probe on the + of the battery. Put the neg probe on the case of the regulator. You should get 12 volts. If not, the reg may have a ground problem.
If everything is checking out so far, then get the engine started, put the neg probe of the meter on the battery neg, and put the + probe of the meter on the "f" terminal of the regulator. You should have some voltage there. The voltage level of the "f" of the regulator will depend on how much the reg wants the alt to put out. If you get no voltage on the "f" terminal of the reg, then it looks like the regulator is bad.
You are getting 12 volts from the green/red to the "s" terminal(there are two different ways this could be wired from the factory, let me know if the green red is not hooked to the "s" but hooked to the "i" terminal).
You said the yellow wire, which is hooked to the "a" is good. You should have 12 volts on the "a" terminal of the regulator.
One more check. Take your voltmeter, and put the + probe on the + of the battery. Put the neg probe on the case of the regulator. You should get 12 volts. If not, the reg may have a ground problem.
If everything is checking out so far, then get the engine started, put the neg probe of the meter on the battery neg, and put the + probe of the meter on the "f" terminal of the regulator. You should have some voltage there. The voltage level of the "f" of the regulator will depend on how much the reg wants the alt to put out. If you get no voltage on the "f" terminal of the reg, then it looks like the regulator is bad.
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Red/green is hooked into the S terminal. 12v at the A terminal. Ground test on the regulator worked and showed the battery voltage.
Ran the motor, and the F terminal was putting out 0.55 V.
Ran the motor, and the F terminal was putting out 0.55 V.
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From: Virginia
.55v does not sound like enough. I would replace the regulator.
P.S. I did a quick summary of your first post, and it sounds like you had it fixed, and the new regulator may have failed. I don't know if they will warrenty it or not. Regulators are easy to fry if the "f" wire touches metal somewhere, or the field in the alternator is grounded out. You put in a new alt with the new regulator, so the alternator should not have burnt the new reg.
Also make sure when you are messing with taking the alt in or out, or the reg, that you disconnect the battery. That is the #1 cause of the fusible link I was talking about earlier getting blown.
P.S. I did a quick summary of your first post, and it sounds like you had it fixed, and the new regulator may have failed. I don't know if they will warrenty it or not. Regulators are easy to fry if the "f" wire touches metal somewhere, or the field in the alternator is grounded out. You put in a new alt with the new regulator, so the alternator should not have burnt the new reg.
Also make sure when you are messing with taking the alt in or out, or the reg, that you disconnect the battery. That is the #1 cause of the fusible link I was talking about earlier getting blown.
Last edited by Franklin2; Apr 25, 2007 at 11:37 PM.
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Success!! 
I replaced the regulator, and it's charging fine now. Before I started the truck up, I went through all the DMM tests again and visually checked the wires (sure don't want to have to go get another VR), and found that the orange wire to the F terminal had a small bit where the insulation was damaged, and it looked like the bare wire might have been touching the alternator before I started messing with the whole thing. That might explain why the regulator burned out, taped that off, and no problems.
Anyways, thanks so much Dave, system's working great now, and I've learneda lot about it (and how useful my DMM is)!
I replaced the regulator, and it's charging fine now. Before I started the truck up, I went through all the DMM tests again and visually checked the wires (sure don't want to have to go get another VR), and found that the orange wire to the F terminal had a small bit where the insulation was damaged, and it looked like the bare wire might have been touching the alternator before I started messing with the whole thing. That might explain why the regulator burned out, taped that off, and no problems.
Anyways, thanks so much Dave, system's working great now, and I've learneda lot about it (and how useful my DMM is)!
