Volatge Issues
Thread Starter
|
Logistics Pro
Joined: Feb 2004
Posts: 4,460
Likes: 14
From: The Land Of Time
Volatge Issues
Hey guys,
One of my friends has a 2000 or 2001 F350. I am not 100% sure if its the 5.4 or the V-10. I am almost certan its a 5.4. Anyway his voltage guage is going up and down and the lights are also dimming and going brighter as this happens. He has replaced the alternators 2 times with MotorCraft parts, that was the 1st. thing I asked him.
We checked the voltag right at the battery and it goes from 14.4-16.8 volts, this happened with both alternators that were replaced. I am thinking that the positive battery cable is corroded but not sure. This truck has about 77k on it and is used daily as he does have a landscaping buisness.
I dont get to see it cause hes a do it yourselfer. I did go to his shop to look at the voltage so I know for a fact its doing it and I was the one that put the second alt. on it for him.
Thanks for the help.
Sarge
One of my friends has a 2000 or 2001 F350. I am not 100% sure if its the 5.4 or the V-10. I am almost certan its a 5.4. Anyway his voltage guage is going up and down and the lights are also dimming and going brighter as this happens. He has replaced the alternators 2 times with MotorCraft parts, that was the 1st. thing I asked him.
We checked the voltag right at the battery and it goes from 14.4-16.8 volts, this happened with both alternators that were replaced. I am thinking that the positive battery cable is corroded but not sure. This truck has about 77k on it and is used daily as he does have a landscaping buisness.
I dont get to see it cause hes a do it yourselfer. I did go to his shop to look at the voltage so I know for a fact its doing it and I was the one that put the second alt. on it for him.
Thanks for the help.
Sarge
Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
If he has a battery to try, it would be worth swapping them for diagnostics. I can't do the ohms law in my head, but it would see that if the amperage would fluctuate if the resistance changed. But I am tired enough it could work both ways.
After putting a second battery in, I would start checking the wires. Make sure the fusable links in the charge wires haven't shorted/blown. Make sure the field has a good connection to the battery. It wouldn't hurt anything to pull the alt and clean where it mounts to the motor (this is the ground path and it needs to be a clean connection.)
It would be a good time to upgrade to 4ga ground and charge wires.
After putting a second battery in, I would start checking the wires. Make sure the fusable links in the charge wires haven't shorted/blown. Make sure the field has a good connection to the battery. It wouldn't hurt anything to pull the alt and clean where it mounts to the motor (this is the ground path and it needs to be a clean connection.)
It would be a good time to upgrade to 4ga ground and charge wires.
Cargo Master
Joined: Apr 2007
Posts: 2,659
Likes: 2
I agree with searching for a loose or corroded ground. If the ground on the alternator charging circuit is poor then it will cause the alternator to overcharge the battery.
It doesn't take much to do this either. A very small amount of corrosion at a terminal ring can cause 0.5 Volt difference or more. In your case I would look for a loose connection or damaged wire that is vibrating as the engine runs. Find that connection, repair, clean the mating surfaces, and tighten up again. See if the problem goes away. It could be anything between battery (-) terminal and alternator (-) terminal.
It doesn't take much to do this either. A very small amount of corrosion at a terminal ring can cause 0.5 Volt difference or more. In your case I would look for a loose connection or damaged wire that is vibrating as the engine runs. Find that connection, repair, clean the mating surfaces, and tighten up again. See if the problem goes away. It could be anything between battery (-) terminal and alternator (-) terminal.
Thread Starter
|
Logistics Pro
Joined: Feb 2004
Posts: 4,460
Likes: 14
From: The Land Of Time
Thanks guys,
He told me he was going to replace both the positive and negative cables as he found some corrosion on the starter end of the positive side. I will post back when he replaces the cables with the results.
Sarge
He told me he was going to replace both the positive and negative cables as he found some corrosion on the starter end of the positive side. I will post back when he replaces the cables with the results.
Sarge
Elder User
Joined: Jan 2002
Posts: 780
Likes: 0
Check the alternator
If the voltage REALLY is going to 16.8 V, he should take the alternator in to have it checked. I know that you said that he replaced it twice, but that does NOT guarantee that it is working properly. As the others have said, check the wiring for good connections,, but the symptom still points to a faulty alternator.
Posting Guru
Joined: Mar 2007
Posts: 1,191
Likes: 1
I am glad you found the carroded wire. The symptoms say that your alternator and regulator are working fine. Something is causing an intermitant draw causing the spike in voltage. symptomatic of a ground /carrosion issue..
