Truck Not Charging
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Truck Not Charging
Hi everyone,
I have a 97 f-150 s-cab 4wd with a 4.6 and auto. My alt gauge hasn't really worked since I bought the truck last month. If I hit the dash the needle will jump. The other day as I was driving the battery went dead. I bought a used one from a junk yard that I know was in working condition. Installed it and charged the battery. Two days later the battery is dead again. Does anyone have any suggestions on what to look for? I don't want to take it to a dealer and spend a million dollars and I can do most of the work myself, I'm just electrically challenged when it comes to these trucks. Does the amp gauge need to work and complete the circuit in order for the truck to alternator to charge? Any help would be greatly appreciated as this is my work truck Thanks alot
I have a 97 f-150 s-cab 4wd with a 4.6 and auto. My alt gauge hasn't really worked since I bought the truck last month. If I hit the dash the needle will jump. The other day as I was driving the battery went dead. I bought a used one from a junk yard that I know was in working condition. Installed it and charged the battery. Two days later the battery is dead again. Does anyone have any suggestions on what to look for? I don't want to take it to a dealer and spend a million dollars and I can do most of the work myself, I'm just electrically challenged when it comes to these trucks. Does the amp gauge need to work and complete the circuit in order for the truck to alternator to charge? Any help would be greatly appreciated as this is my work truck Thanks alot
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Joined: Dec 2001
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From: Louisville,Ky.
First, there should be a large fuse in a power distribution box under the hood for the alternator. Check it first.
Put a good battery in it and take it to a local place like AutoZone and have them test the alternator on the truck. Sounds like it may be bad. I don't think that the voltmeter has to complete a circuit to charge.
Put a good battery in it and take it to a local place like AutoZone and have them test the alternator on the truck. Sounds like it may be bad. I don't think that the voltmeter has to complete a circuit to charge.
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From: South Kitsap County, WA
The alt gauge is a volt meter, as Jimmy pointed out. It's in parallel with the output of the alternator. If it is working right it is giving a guestimate on how much your alternator is sending to your battery. If you're not showing an output then the battery isn't getting any juice.
I concur with Jimmy... get the alternator checked out. Then look at the condition of the cables going to the battery. Make sure they're in decent shape (a resistance check of less than 0.5 ohms is the best way). The lower the resistance the better the juice flows.
-Kerry
I concur with Jimmy... get the alternator checked out. Then look at the condition of the cables going to the battery. Make sure they're in decent shape (a resistance check of less than 0.5 ohms is the best way). The lower the resistance the better the juice flows.
-Kerry
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Fuse #19 (10 amp) powers through the guage and is the excite circuit power input on the light green/red wire to the alt. There is also a 20 amp inline fuse for the orange/light blue wire to the alt. and a 175 amp megafuse for the battery lead to alt. The guage has a 470 ohm resistor in parallel so a defective guage should'nt cause a no charge. Unplug the vlotage regulator connector, key on, check for power to the light green/ red wire, and the orange/light blue wire if ok, fuses are ok, reconnect and start truck and check for 6 volts on the white/black wire, if not get another alt.
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Hi everyone and thanks for the input. Here is what I know so far. The alt. and the battery are perfect, took them off and had them checked. ALL fuses that I could find are good. I checked the #19 fuse under the dash and under the hood and they are good. I pulled the connector off the voltage regulator and there is no power to the green wire which I'm assuming is the ignition side. The other wire has constant power to it. I traced the wire to behind the mega-fuses and have no power to were it goes into a connector. Can a bad ignition switch cause this problem? Where does the excite wire lead to? Can I bypass this wire and hook up my own wire to jump start the alternator? I plan on tackling this tomorrow and if I can't get it to work then it's off to the garage with it. Thanks again in advance.
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Thanks to everyone who replied to my post. I found the problem and repaired the truck today. The #19 fuse under the dash was good, but the blades of the fuse weren't making the proper connection. If I wiggled the fuse the alternator worked hit and miss. All I did was to bend the blades a little and now it works perfect. Just wanted to let everyone know in case they might run into this sort of thing. Who could have ever thought that. Thanks again to everyone, Ivan
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Joined: Jul 2001
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From: South Kitsap County, WA
Thanks for letting us know you got it fixed. Word of caution: If you have a high resistance connection, which is what the fuse blades may be creating, you can get enough heat to start a fire. I'd keep looking at #19 until you're satisfied the fuse isn't going to be a problem in the future.
Thanks Fordtech1 for the inside input on the charging system. We should put that in the tech section... Dave?
-Kerry
Thanks Fordtech1 for the inside input on the charging system. We should put that in the tech section... Dave?
-Kerry
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