1 Wire Alternator Problem
Thread Starter
|
Logistics Pro
Joined: Oct 2002
Posts: 4,489
Likes: 5
From: Valley Center, CA
Yea Ax, I'm suspicious too. This was supposed to be easy! You mentioned about shecking it with no battery wire. Doesn't an alternator need a battery wire attached to make electrictiy? Yup,there were no instructions in the box. And the only help I got was from the clerk at the shop. I told him that I assumed I was supposed to hook the battery wire up to the large post with the red ring around it. He said that was correct. 
So it's back to the shop I go. But, as it turned out the first unit was not even for a Ford (even though it bolted in), and the unit I have now was the only one they still had in stock and was the floor model. (I wonder if it had been dropped or tampered with.) I don't know how I could be screwing this up, what with only one wire to hook up. Jag
So it's back to the shop I go. But, as it turned out the first unit was not even for a Ford (even though it bolted in), and the unit I have now was the only one they still had in stock and was the floor model. (I wonder if it had been dropped or tampered with.) I don't know how I could be screwing this up, what with only one wire to hook up. Jag
Hotshot
Joined: Oct 2004
Posts: 15,882
Likes: 88
From: Durham NC
Do you have a volt-ohm meter? set it @ next higher scale than 12V DC. Disconnect the output wire, with engine running touch red lead to output term, the black to ground. Alternator output should read ~ 14 v. at 2000 RPMs.
If the output is correct, I'd suspect you are getting feedback or a short someplace, probably in the AC circuit since that kills the engine. Have you tried pulling the AC fuse and see what happens? Why were you changing the alternator, appearance or charging problem?
If the output is correct, I'd suspect you are getting feedback or a short someplace, probably in the AC circuit since that kills the engine. Have you tried pulling the AC fuse and see what happens? Why were you changing the alternator, appearance or charging problem?
Last edited by AXracer; Jun 13, 2005 at 12:14 PM.
Thread Starter
|
Logistics Pro
Joined: Oct 2002
Posts: 4,489
Likes: 5
From: Valley Center, CA
I am changing the alternator because of charging problems. If I run the truck without A/C or lights, then the stock alternator puts out 14.5 v 
But if I turn on the A/C, then the voltage drops to 12.5. 
I've had the stock alternator and the external regulator checked by Autozone where I bought them. They say that they are good even though I thought it was a bad regulator. So I thought that by going with the 1-wire unit, I could eliminate the external regulator as a possible source of the problem. Question: If I had some sort of short in the A/C unit, then wouldn't it just blow the fuse? Thanks, Jag
But if I turn on the A/C, then the voltage drops to 12.5. I've had the stock alternator and the external regulator checked by Autozone where I bought them. They say that they are good even though I thought it was a bad regulator. So I thought that by going with the 1-wire unit, I could eliminate the external regulator as a possible source of the problem. Question: If I had some sort of short in the A/C unit, then wouldn't it just blow the fuse? Thanks, Jag
Hotshot
Joined: Oct 2004
Posts: 15,882
Likes: 88
From: Durham NC
not necessarily, there could be enough load to keep the fuse from blowing, just pulling the voltage down below what the ignition needs such as a bad bearing or winding in the blower motor or a bad clutch electromagnet. From what I'm hearing you say, the same problem has been present all along (with the old alternator) and it tested good off the truck. So putting on a different good alternator isn't likely to solve the problem.
There is something amiss in your AC circuit IMHO you're chasing the wrong horse.
You could also be getting feedback in the AC and/or headlight circuit thru a relay.
There is something amiss in your AC circuit IMHO you're chasing the wrong horse.
You could also be getting feedback in the AC and/or headlight circuit thru a relay.
Last edited by AXracer; Jun 13, 2005 at 02:26 PM.
Fleet Owner
Joined: Jul 2004
Posts: 27,286
Likes: 1,050
From: NM
I haven't seen how you're hooking the 1-wire up; are you using any of the stock harness? If so, that could be part of the problem.
But back to your original problem; Watch your voltmeter as the A/C clutch kicks on and off; they draw a lot of current when in good shape (10 amps +/-), and if they develop a short in their hold-in winding, can draw 30+ amps (it will be getting very hot, another thing to look for). Anyway, if the voltage is OK when it's off, but drops when it is on, you've got your culprit!
But back to your original problem; Watch your voltmeter as the A/C clutch kicks on and off; they draw a lot of current when in good shape (10 amps +/-), and if they develop a short in their hold-in winding, can draw 30+ amps (it will be getting very hot, another thing to look for). Anyway, if the voltage is OK when it's off, but drops when it is on, you've got your culprit!
Hotshot
Joined: Oct 2004
Posts: 15,882
Likes: 88
From: Durham NC
It's possible the clutch is frozen as well so that when the magnet trys to pull it in it can't so it keep trying. you should be able to see the clutch close when the AC is turned on. One last idea, the compressor could have a bad bearing or seal or even be out of refrigerant and is overloading the engine.
Last edited by AXracer; Jun 13, 2005 at 03:00 PM.
Thread Starter
|
Logistics Pro
Joined: Oct 2002
Posts: 4,489
Likes: 5
From: Valley Center, CA
All good thoughts. But I believe that I may have found a simpler solution. I contacted the local manufacturer of these 1-wire alternators. I took it to him to check for proper operation. The unit checked out, but it did have a noise in the bearing. So they took it apart to fix that and also rotated the body so that the power post was positioned at 1:00 instead of 9:00. The problem, as diagnosed by the tech, is the way I had my accessories wired. 
It sounds strange, but he told me not to hook the main feed for my fan, lights, and fuel pump to the back of the alternator! He wants me to change the feed directly to the battery so that the alternator does see the power drain so readily. I'll try it tonight to see if I was cause of all the trouble. 
Jag
It sounds strange, but he told me not to hook the main feed for my fan, lights, and fuel pump to the back of the alternator! He wants me to change the feed directly to the battery so that the alternator does see the power drain so readily. I'll try it tonight to see if I was cause of all the trouble. Jag
Hotshot
Joined: Oct 2004
Posts: 15,882
Likes: 88
From: Durham NC
You have your accessories wired directly to the alternator? That IS likely the cuprit, nothing should be wired directly to the alternator but the battery.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Fleet Mechanic
Joined: Jun 2004
Posts: 1,766
Likes: 39
From: Minnesota
From the reading I have done. The problem with a 1 wire unit as I understand it is that they do not have a voltage sensing circuit externally. So the voltage will reduce with a load the same as the old alternator you had did. The unit keeps a constant voltage internally and does not adjust for external variation. So even if the head lights are on reducing the system voltage to 12 volts the alternator internally is at 14 volts and will not change. That is why you see the 1 wire units on old tractors with a limited load.
Thread Starter
|
Logistics Pro
Joined: Oct 2002
Posts: 4,489
Likes: 5
From: Valley Center, CA
It turns out that the wire for the excessories on the back was only for the headlights. I disconnected it, but the alternator still only puts out 12.5v with the A'C off. I'm going to put a good charge on the battery and then check the amp draw from the electric fuel pump and fan. Jag
Hotshot
Joined: Oct 2004
Posts: 15,882
Likes: 88
From: Durham NC
Most alternators do not produce full voltage output at idle try measuring the output @ ~ 2K RPM. Are you putting the VOM in series with the output terminal and battery or are you disconnecting the wire to the battery and measuring from the output terminal to ground?
Thread Starter
|
Logistics Pro
Joined: Oct 2002
Posts: 4,489
Likes: 5
From: Valley Center, CA
Unfortuantely, I've been out of town for three days in SF. Ax, I haven't got that far. The 12.5v I measured was obtained by putting my multi-meter on DC (50-volt range) current and clipping the ground wire to the engine and the hot wire to the post on the back of the alternator. Then, while it was hooked up this way, I tried reving the engine 2-3000 rpm. It might have moved up closer to 13v. I'm planning on hooking up the meter in series between the output post and the battery wire. Should I try to ground also? Sorry for such basic questions, but I'm not very familiar with electrical problems. Jag 
Sorry for such basic questions, but I'm not very familiar with electrical problems. Jag
Hotshot
Joined: Oct 2004
Posts: 15,882
Likes: 88
From: Durham NC
I don't know for sure but I'd expect as long as the regulator "sees" a fully charged battery on the other end of the output it will throttle back the alternator to prevent overcharging. I don't think you'll see full output unless you have a dead battery or a high load. I really wonder if your actual problem is in the wiring itself? You can get a feedback loop thru a relay which can require wiring in a diode to correct. Have you installed relays on your headlights or other acessories?