Battery, alt. or both?
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Battery, alt. or both?
This morning I went to start my truck. It started fine, but I noticed the voltage gauge was down almost on the bottom peg. No charging light on. I have a power inverter hooked up that reads battery voltage. It read 11.5 volts. I've noticed since I started using the inverter and monitoring battery voltage that it usually reads around 11.5 to 12.5 for the first couple of minutes after starting and then jumps up to 14.2 or 14.3 but the voltage gauge is usually in the normal range. This morning after several minutes of running the voltage nver came up. Also, about two weeks ago I noticed after driving ten or fifteen minutes that the voltage gauge had dropped pretty low...still no charge light and the voltage on the inverter still read 14.3 v. I swithced the truck off and restarted and everything was fine. Do you think it could be the battery or the alt. I've checked the battery connections and they are good. I hope I don't have another loose ground or something to have to try to chase down. Any help would be greatly appreciated. Thanks in advance.
Lead Driver
Joined: Jan 2007
Posts: 6,708
Likes: 5
From: Kiowa CO
To have the battery voltage in the 11.5 range at first start up then jump to 14.2 is normal because your GPR is activating your GP's. However, it does sound like your alternator is failing on you. Have it tested.
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Joined: Nov 2010
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From: Spencer, ma
Im surprised the truck fired at 11v... simple way to tell if the alt is working is with a multimeter (if you have one)
test each battery this way..
Voltage while off.. should be atleast 12v
once runing it should jump to 13.8 or higher.
Sounds like your alt is on its way out.. your meter connected to your inverter is basicly doing the same thing and giving you the same reading.
I havent owned this truck long enough but most fords have the batt indicator on the dash and should be on with the numbers you gave.. the bulb could be burned out.
test each battery this way..
Voltage while off.. should be atleast 12v
once runing it should jump to 13.8 or higher.
Sounds like your alt is on its way out.. your meter connected to your inverter is basicly doing the same thing and giving you the same reading.
I havent owned this truck long enough but most fords have the batt indicator on the dash and should be on with the numbers you gave.. the bulb could be burned out.
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Ok...i was having the above problem last week. Alt. and batteries checked fine. This morning went to start and same problem. Voltage at power outlet was 12.3 before glow plugs. 11.4 with plugs before starting. 12.0 after starting and 14.3 after glow plugs cycled off. Voltage gauge on dash barely moved off of bottom. Started fine, but the needle stayed low. Drove approximately 20 miles with gauge almost on bottom peg...voltage through in inverter plugged into power outlet maintained 14.2-14.3 volts. Where does the gauge on the dash get its measurement at? Does it read actual voltage, or is it getting a signal from the PCM? I don't know if it is related or not, but it was in the low 20's here this morning, and it was fairly cold the last time this occured. Every other time since the last time this occured everything has been fine.
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I forgot to mention that after about 20 miles of driving the gauge suddenly jumped from almost nothing to its normal position instantly and stayed up the rest of my trip.
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Cargo Master
Joined: Feb 2010
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From: Delta, CO
I really don't know but I don't put much stock in the factory gauges on these things, seems like the gauges are glorified dummy lights. Sounds like what your seeing at your outlet is pretty good....JMO
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Senior User
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From: Spencer, ma
The voltage in the batteries seems low, as soon at it fires the Alt should bring that up 13.8 and above right away.. if it takes a while for the gauge to react then I would say your regulator in the alt is faulty.. Not sure if they are replaceable in the SD. if they are not I would replace the alt.
I live in Mass and haven't fired mine in 4 days at 20 degrees.. Ill check mine today when I get in to the shop.
I live in Mass and haven't fired mine in 4 days at 20 degrees.. Ill check mine today when I get in to the shop.
Cargo Master
Joined: Feb 2010
Posts: 2,298
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From: Delta, CO
The voltage in the batteries seems low, as soon at it fires the Alt should bring that up 13.8 and above right away.. if it takes a while for the gauge to react then I would say your regulator in the alt is faulty.. Not sure if they are replaceable in the SD. if they are not I would replace the alt.
I live in Mass and haven't fired mine in 4 days at 20 degrees.. Ill check mine today when I get in to the shop.
I live in Mass and haven't fired mine in 4 days at 20 degrees.. Ill check mine today when I get in to the shop.
Senior User
Joined: Nov 2010
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From: Spencer, ma
Ok ill admit I am new to the PS world.. But afaik when the WTS light goes out the relay for the glow plugs is off. I can watch my lights dim as the relay is on and as soon as the WTS lights goes out the lights become bright telling me that it is not drawing power and off.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
The timer in the PCM for the GPR has nothing to do with the WTS light timer.
On a cold day, the GP's will likely be on longer than the WTS light, and if it's warm enough, the GP's may not come on at all.
However, the light stays on for it's pre-determined interval, either way.
A lot of guys here have added an LED and resistor to the output terminal of the GPR, mounting it inside the cab for operational verification.
Pop
On a cold day, the GP's will likely be on longer than the WTS light, and if it's warm enough, the GP's may not come on at all.
However, the light stays on for it's pre-determined interval, either way.
A lot of guys here have added an LED and resistor to the output terminal of the GPR, mounting it inside the cab for operational verification.
Pop
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
Ok ill admit I am new to the PS world.. But afaik when the WTS light goes out the relay for the glow plugs is off. I can watch my lights dim as the relay is on and as soon as the WTS lights goes out the lights become bright telling me that it is not drawing power and off.
Hotshot
Joined: Feb 2007
Posts: 10,499
Likes: 10
From: Sterling Heights,Mi
Im surprised the truck fired at 11v... simple way to tell if the alt is working is with a multimeter (if you have one)
test each battery this way..
Voltage while off.. should be atleast 12v
once runing it should jump to 13.8 or higher.
Sounds like your alt is on its way out.. your meter connected to your inverter is basicly doing the same thing and giving you the same reading.
I havent owned this truck long enough but most fords have the batt indicator on the dash and should be on with the numbers you gave.. the bulb could be burned out.
test each battery this way..
Voltage while off.. should be atleast 12v
once runing it should jump to 13.8 or higher.
Sounds like your alt is on its way out.. your meter connected to your inverter is basicly doing the same thing and giving you the same reading.
I havent owned this truck long enough but most fords have the batt indicator on the dash and should be on with the numbers you gave.. the bulb could be burned out.
10.5 is the final number for our trucks not starting,
