Low voltage - while running.

[Shaft333]

Today I noticed that my voltage was about 12v while I was moving (not just at idle).
It lasted as such for about 10miles or so.
Almost seems like the alternator isn't doing it's thing.

It read a consistant 12v even as I turned on and off accessories including air, high fan, stereo and windows (although holding the switch down after the window was fully open did cause a dip in the voltage).

As I said, all this is even with the motor revving.

[Bradley G]

I have never noticed the amp guage move.Somewhat like the oil guage it is always in the same spot too.( I know the oil pressure guage is only on or off)The amp guage dip while holding down the window switch sounds normal.

Bradley G


Today I noticed that my voltage was about 12v while I was moving (not just at idle).
It lasted as such for about 10miles or so.
Almost seems like the alternator isn't doing it's thing.

It read a consistant 12v even as I turned on and off accessories including air, high fan, stereo and windows (although holding the switch down after the window was fully open did cause a dip in the voltage).

As I said, all this is even with the motor revving.

[Donny Carlson]

Today I noticed that my voltage was about 12v while I was moving (not just at idle).
It lasted as such for about 10miles or so.
Almost seems like the alternator isn't doing it's thing.

It read a consistant 12v even as I turned on and off accessories including air, high fan, stereo and windows (although holding the switch down after the window was fully open did cause a dip in the voltage).

As I said, all this is even with the motor revving.
I recall something similar happening back in the days when I still had OEM gauges. IIRC, it disappeared on the next start cycle. Since replacement of the gauge there has never been a recurrance.

[AzMarauder]

I have never noticed the amp guage move.Somewhat like the oil guage it is always in the same spot too.( I know the oil pressure guage is only on or off)The amp guage dip while holding down the window switch sounds normal.

Bradley G
I am running Lidio's XCalibrator MM tune. One of the features is it allows the Alt to be shut down at WOT. Trust me... the Volt Gauge moves.... :D

[MENINBLK]

Today I noticed that my voltage was about 12v while I was moving (not just at idle).
It lasted as such for about 10miles or so.
Almost seems like the alternator isn't doing it's thing.

It read a consistant 12v even as I turned on and off accessories including air, high fan, stereo and windows (although holding the switch down after the window was fully open did cause a dip in the voltage).

As I said, all this is even with the motor revving.

If you are looking at the OEM Gauge, you still have another 1.5V ABOVE what you are seeing so don't sweat it.
The OEM Voltmeter isn't as accurate as you think it is and it reads LOWER than that the voltage actually is.
If you replace the Voltmeter with a REAL Autometer Voltmeter you'll find that your Voltage will read higher.
Mine usually reads about 14.5v when running anything other than idle.
At idle in drive is about 13v - 14v depending on whether my lights are on or not.
I've only seen it dip to 12.5v very rarely, like in a panic stop,
or if the AC clicks on when the lights are on and I'm sitting at a light.
But it never stays at 12.5v for long.

Someone is working on a high output alternator for the Marauder/Mustang.
Its supposed to output over 100A at idle...
Now, if I could just remember where I read it.

[Marauderjack]

Get a VOM and check it before you take it in for service....The gauge could be wrong?? :confused:

Should have 13.8 Volts or so while running!! :o

Marauderjack :cool:

[Shaft333]

I should add that the gage is reading about 1.5v lower than what it was reading the day before.

I'm actually suspecting the climate may have something to do with this. The charging system doesn't need to work as hard to keep everything happy.

I'll keep an eye on it.

[RF Overlord]

I'll keep an eye on it.

While you're keeping an eye on your gauges, notice that the oil pressure gauge doesn't ever move; that's because it's a fake. If you're interested, there's a "how-to" in the FAQ which details how to replace the OEM fake gauge with a real working one.

[Shaft333]

While you're keeping an eye on your gauges, notice that the oil pressure gauge doesn't ever move; that's because it's a fake. If you're interested, there's a "how-to" in the FAQ which details how to replace the OEM fake gauge with a real working one. I know. However, thank you for the input. :beer:

[Bradley G]

Thanks AZ,

I too run Lidio's tune.I don't look down (@ guages) too often, when I stomp the go pedal:P.But I will make a mental note to look one of these times.
Bradley G

I am running Lidio's XCalibrator MM tune. One of the features is it allows the Alt to be shut down at WOT. Trust me... the Volt Gauge moves.... :D

[jaywish]

As mentioned earlier in the thread,

The best bet here is to start the car. Check the guage reading after letting the car run for a min or 2, open the hood and put a volt meter across the battery terminals.

It shoud read aprox 14 volts. If not, go to the dealer.

If the bat reads 14 then the guage is off a little. Could be wiring or the guage.

Jay

[bugsys03]

[QUOTE=Bradley G]I have never noticed the amp guage move.Somewhat like the oil guage it is always in the same spot too.( I know the oil pressure guage is only on or off)The amp guage dip while holding down the window switch sounds normal.


My amp gauge is functional for sure. Thats how I noticed symptoms similar to whats been posted here. Took it in to the dealer and got a new alternator under warranty, all good. The replacement does not have the clutch feature though.

[fastcar]

If you are looking at the OEM Gauge, you still have another 1.5V ABOVE what you are seeing so don't sweat it.
The OEM Voltmeter isn't as accurate as you think it is and it reads LOWER than that the voltage actually is.
If you replace the Voltmeter with a REAL Autometer Voltmeter you'll find that your Voltage will read higher.
Mine usually reads about 14.5v when running anything other than idle.
At idle in drive is about 13v - 14v depending on whether my lights are on or not.
I've only seen it dip to 12.5v very rarely, like in a panic stop,
or if the AC clicks on when the lights are on and I'm sitting at a light.
But it never stays at 12.5v for long.

Someone is working on a high output alternator for the Marauder/Mustang.
Its supposed to output over 100A at idle...
Now, if I could just remember where I read it.

Is this true? I just noticed tonight that my Autometer Voltmeter reads 12 volts at idle, and only 13 volts at higher RPM! Yes, I have UDs, but at RPM, I believed a Ford charging system is suppose to be at 14.6 volts...

Is this really true about the Voltmeter??? Is my system actually OK?

fastcar:burnout:

[Blackened300a]

Is this true? I just noticed tonight that my Autometer Voltmeter reads 12 volts at idle, and only 13 volts at higher RPM! Yes, I have UDs, but at RPM, I believed a Ford charging system is suppose to be at 14.6 volts...

Is this really true about the Voltmeter??? Is my system actually OK?

fastcar:burnout:

Before I replaced my oem gauge to a "real" gauge, my voltage would sometimes drop down to 11 volt's while driving. Other times it would be at 14. After the install, Its stays a little above 14 volts and if I have my HID headlights on with the A/C and wipers going, I have seen it dip just below 13 volts and build back up to 14.
Your alternator is fine, the oem gauge sucks.

[jonroe]

If you are looking at the OEM Gauge, you still have another 1.5V ABOVE what you are seeing so don't sweat it.
The OEM Voltmeter isn't as accurate as you think it is and it reads LOWER than that the voltage actually is.
If you replace the Voltmeter with a REAL Autometer Voltmeter you'll find that your Voltage will read higher.
Mine usually reads about 14.5v when running anything other than idle.
At idle in drive is about 13v - 14v depending on whether my lights are on or not.
I've only seen it dip to 12.5v very rarely, like in a panic stop,
or if the AC clicks on when the lights are on and I'm sitting at a light.
But it never stays at 12.5v for long.

Your case is not true for everyone - your gauge only. The OEM volt meter is as real as the "aftermarket" Autometer voltmeter and is supposed to read correctly. The computer and voltage regulator want to hold the voltage during normal running at about 13.8 volts. I can see that clearly with my OBDII port gauge. My original OEM voltmeter was pretty close most of the time. It read about 14 while running unless at idle with lots of accessories on. It read about 12 with key on, no start. It dropped to about 10 while starting motor was on. This is normal behavior. Then, when I replaced the truly fake OEM oil pressure gauge I also got the companion new voltmeter just to complement the appearance. I was disappointed to see that the new voltmeter was about 0.5 to 0.6 volts high all the time. So, in my case the OEM voltmeter was quite accurate and the aftermarket one was inaccurate. Now, I have removed the Autometer voltmeter altogether and have the OBDII gauge in its place. Anyway, the behavior depends on the voltmeter not the fact that it is OEM.

[jonroe]

Is this true? I just noticed tonight that my Autometer Voltmeter reads 12 volts at idle, and only 13 volts at higher RPM! Yes, I have UDs, but at RPM, I believed a Ford charging system is suppose to be at 14.6 volts...

Is this really true about the Voltmeter??? Is my system actually OK?

fastcar:burnout:

You need your system checked with an accurate test voltmeter. You may or may not be okay. I would check it.

[jonroe]

Get a VOM and check it before you take it in for service....The gauge could be wrong?? :confused:

Should have 13.8 Volts or so while running!! :o

Marauderjack :cool:

Correct. 13.8 volts is the target for the computer and voltage regulator. It stays pretty close to that unless under heavy electrical load and low rpm.

[cyclopsram]

Just get a real voltmeter and put a cigarette lighter plug on it and put it in your ciggie lighter socket and you can monitor the voltage for real all the time...any vehicle, anywhere, day or nite...rain or snow...

[sicilianmarquis]

dude 12v isnt going to kill your car, i wouldnt worry about it to much, was it hot outside? do you have a black car? i've notice on mine if it is hotter outside then usual, sometimes my voltage is less then normal, butthats because its working harder to do normal operations

[racorcey]

I have never noticed the amp guage move.
Bradley G

Brad....Amp meters/gauges in cars went out a while ago. Last one built into a car in the U.S. was 1962. I guess you've figured out by now that we have Volt meters. Personally, being an engineer, I'd like to have BOTH gauges.

[racorcey]

Today I noticed that my voltage was about 12v while I was moving (not just at idle).
It lasted as such for about 10miles or so.
Almost seems like the alternator isn't doing it's thing.


Shaft....as some of the others have already posted, the voltmeter is quite inaccurate on this vehicle. The ONLY way you're going to get a good reading is by monitoring directly across the battery terminals. Unfortunately, Ford chose to look at the voltage from an accessory spot on the fuse panel, which is subject to a lot of voltage drop due to wiring and the different current draw of various accessories.

If you do find that your alternator is questionable, as many have found here, that wouldn't be unusual. Unlike the SOHC 4.6 motor, this alternator sits inside an intake manifold "well" on the DOHC engine, subjecting the alternator to more heat, and therefor making it much more unreliable long term.

[sicilianmarquis]

ok i just looked it up on ALLDATA at school, it says that it is completly controlled by the PCM, meaning its only going to pull what it needs, no worrys, maybe u want to hook up a meter and check your cranking amps

[jonroe]

As I said earlier, the target the PCM wants is about 13.8 when the draw is not overwhelming a slow running alternator. This number does go down a little in very hot conditions as well. In any event if you truly have only 12v when the engine is cruising down the highway, you do have a problem and your battery will eventually drain and die.

[fastcar]

dude 12v isnt going to kill your car, i wouldnt worry about it to much, was it hot outside? do you have a black car? i've notice on mine if it is hotter outside then usual, sometimes my voltage is less then normal, butthats because its working harder to do normal operations

Man, are you serious?

[fastcar]

You need your system checked with an accurate test voltmeter. You may or may not be okay. I would check it.

Thanks guys for the help. I have surmised that:

Our gauges tend to be unreliable, though some report otherwise.

13.8 is the target.

I can use my Multimeter across the battery to check it out.

Great ideas, and info, folks, I really appreciate it!

fastcar:burnout:

[mark751]

I have had the same problem on occasion i noticed it when i stop for gas and restart the car. When i turn the head lights on right away the voltage stays at 12 volts like the alternater is not working and the dash lights stay dim then at about 5 miles or so the alternater kicks in and the voltage goes to 14+ the lights get brighter again.. now thats said i noticed if i waite a few seconds after starting the car and not turn the lights on the voltage goes to 14 and stays there.. you did not mention if your problem occured at night or day. hope this helps as i said i have had the problem before.

[jonroe]

You'll notice that the charging voltage goes up slightly in cold weather and goes down slightly in hot weather. Late summer with temps in the mid to high 80s I was showing 13.8 at the OBD port. With the cooler fall weather it is 13.9-14.0.