Alternator, battery, or electrical?

120

Asked by Feb 14, 2015 at 10:19 PM about the 1996 Ford F-150

Question type: Maintenance & Repair

My truck had been running fine, until a couple of days ago. It started fine, all gauges reading normal (I'm a habitual and constant gauge-checker). I was out running errands, and after driving for a couple of miles, turned off the truck, and when I went to start it again, just got the "click." Well, I'd been having some issues with the neutral safety switch, but this felt like a battery issue. I checked the terminals, and the positive was a little loose, so I tightened it up, jumped it - it started right up - and after checking the gauges to make sure all was well went on my way. After a couple of miles, the engine shut off - as though you'd turned the key - and then popped right on again! (When it was off, all gauges were dead and so was the engine. It came back on - all the way, gauges and everything - within about a second.) I parked it, let it sit, and jumped it again. Same thing: Started right up, all systems go, only this time the lights, gauges, and everything but the engine shut down, with the engine finally dying after maybe another mile or so. Fine. Towed it home. Replaced the lead from battery to starter (it was a little worn), tried it again. This time I noticed that when the jumper cables are hooked up to the battery, the alternator gauge shows charging - and a little higher than usual, as I would expect. As soon as the jumper cables are disconnected, the alternator gauge shows zero (all other gauges showing appropriate levels), and the engine dies almost immediately.

47 Answers

1,235

First thing I'd do it take the battery and alternator out and take it to a parts store like advance auto parts and them test them just to rule them out. There is also a fuseable link on the positive battery cable, if that fails then the alternator can not charge the battery. To check the fuseable link you need a volt meter. Pierce the cable at either end with the volt meter leads with the engine running it should show at least battery voltage 12.5 volts. If no voltage is present then the positive battery cable must be replaced. If all three of them check out then check your starter solenoid if it's fender mounted. I have seen on some f150's where the post for the solenoid breal off inside the solenoid and caused an open circuit and shut the vehicle off. If everything is tight and the post on the solenoid do not wiggle Then you have an electrical problem or pcm (powertrain control module) problem.

5 of 5 people found this helpful.
19,235

Your alternator is bad. Take it off and have it tested

7 of 7 people found this helpful.
120

Thanks to both of you. I was thinking it was the alternator, but I'm thrown by the positive reading on the gauge when the jumper cables are attached. After perusing other posts, I'm going to check all related connections, try it again, and if the problem persists, the alternator is coming off. Thanks!

1 of 1 people found this helpful.
19,235

It's reading the voltage of the other vehicle when the cables are attached

4 of 4 people found this helpful.
5,445

Your battery is probably good unless you have run it down trying to start the truck. If so, just give it a good overnight slow charge. From your description it sounds like the whole problem is alternator.

2 of 2 people found this helpful.
120

Andrew: I thought maybe that was what was happening, but I didn't know if that was possible. Thanks for confirming my suspicions!

120

Follow-up: I decided to have the battery charged while I was switching out the alternator, and after I'd gotten the new alternator installed, I went back to the parts store ( where I'd left the battery) and they informed me that the battery was bad - it had a bad cell. Wondering if I'd needlessly installed a new alternator, I had them test the old one. It was basically fried: Several internal components were completely shot. It's worth noting that there was absolutely no sign of any damage whatsoever to the naked eye: No scorching, nothing. Nonetheless, it was totally destroyed. From reading other posts and other research, I'm guessing what happened is that the cell in the battery went bad, and then the alternator fried itself trying to maintain a charge in a bad battery. For anyone doing their own research: Again, despite the fact that there were no visible signs of damage to the alternator externally, it was in fact totally shot. I replaced both the alternator and the battery, and all is well. Again, for those of you who are researching: This was an incredibly simple and easy fix. The 1996/7 Ford F-150 is an easy engine to work on, especially regarding this specific issue and others like it. Finally, my sincere thanks to those of you who so graciously took the time and made the effort to offer your advice. I greatly appreciate it, and am pleased to say that my truck is back up and running, which means my grandfather's cattle have enough hay to get through the next few weeks.

8 of 8 people found this helpful.
120

One final note for those of you who are researching your own problems: If you're thinking "well, how am I supposed to know if or when a cell in my battery goes bad?" Here's the thing: It turns out that the battery was 13 - yes, thirteen - years old! Of course, had I known that, I'd have put a new one in long ago, and more than likely this wouldn't have happened. My advice - and I'm not an expert, but based on what I've read - is to change your battery if it's 5 years old or older, or at the very least take it in and get it tested. Your local parts store will do it for free. And always keep in mind that no matter how we may try to prevent things like this from happening: Life is unpredictable, and sometimes bad things happen. Good luck!

3 of 3 people found this helpful.
5,445

You figurred it out. The battery celll went bad and then the Alternator blew the diods trying to keep it going. If this is not a daily driver, you might want to consider getting a Battery Tender, I have one on me tractor, classic cars and spare battery. Well worth the money. Glad you got it fixed.

1 of 1 people found this helpful.
20

Same thing happened to me so I bought a new alternator and drove it for a couple days and then all of a sudden the battery gauge when right to zero and shut the truck off.

2 of 2 people found this helpful.
40

Question - I am having similar problems with me 2004-F150. At first, I thought it was just a bad battery. I replaced it - it was over 5 years old anyway. Two days later I go out and it is completely dead. Now I am thinking it is the alternator. I had it checked at Auto Zone and they said it was OK. I am having problems with the electrical system at the same time - radio not working, radio playing but not lights on the radio, Heat will not adjust and a few other things. Do I have a bad alternator? Or do I have electrical problems/fuse problems?

3 of 3 people found this helpful.

We've had similar problems and we've unhooked theeverything we can unhook and it's still drawing 1.7 volts. We replaced the battery and fuse box and fuel pump driver module and nothing has made a difference. Any advice would be helpful?

5,445

Make sure your courtesy lights, trunk or hood lights are turning off. I had a door ajar message and they were all shut tight but the battery kept going down. Turned out the door switch was shorting.

40

After checking all the electrical boxes, fuses and controls, we found out that the radio was not shutting off after you opened the door. Replaced the radio and everything is fine. It took it about 2 days to run the battery down.

1 of 1 people found this helpful.
10

I have similar problems. I replaced the battery and alternator in January and it has been ok since. Today the truck died. Battery guage went down first, radio died then every thing died. When I turn the key on all the guages peg and then go to normal. Jumped and tested . Have only 11.8 vdc and batt guage shows charging but the truck dies eventually after cables removed.

1 of 1 people found this helpful.
10

Any help on my previous post?

20

(everybody) Check wire bundle under 2004-up F150 driver's door/rocker panel. Dirt fills inside wiring loom. (get underneath truck with safety glasses and expect dirt to fall in your eyes &/or ears.) Dirt turns to mud in rain and shorts-out wiring. Pull wiring harness down, pull off tape and loom ...clean and inspect contacts (after I found this design flaw I re-hung my harness so it would be less prone to collecting future garbage) After scraping contact pins with a razor knife use "3M Silicone Paste" inside electrical connectors . Also check above your rear axle (on the driver's side) for your fuel module which corrodes because it lacks legs. (aluminum housing mounted to steel ...swells up, shorts out and dies) Might help to remove your spare because it's awkwardly hidden. Replace this with a Dorman brand unit which has legs/stand-offs to remount it properly. Also check for amateur installed add-on trailer wiring or a dirty OEM connector.

20

Dead battery or not: Consider getting a Yellow-Top Optima battery 34/78. The Yellow Top is designed to be used like a normal battery but it can recover faster and stay healthier because it is also designed for a little abuse/heavier drain. Standard batteries will not recover 100% from a complete discharge so a Yellow Optima is a nice choice if $220 is in your budget. I've been using them for 20 years in multiple cars and 7 years per yellow battery is average. (put the old bat in your beater car or trade it in at Advance for the $20 core charge) A strong battery remove/reduce stress from any electrical system and that equals fewer failures of fans, switches, window/seat motors etc. I'm upgrading to a 200 amp 6G alternator for my 2004 FX4. I suspect my brushes/regulator are bad/disintegrated at 158,000 due to age and my love of A/C and loud music :) Note: most cheap replacement alternators are rated 110 amp and many OEM units were 130. Check your F150 factory window/sales sticker (if you have it)... you may have a 130 amp 6G alt listed as an upgrade.

20

Alternative "hacks" and trouble-shooting: Many salvage yards sell some really good used car batteries. (They usually charge a core- charge so find somebody's wasted car battery and take it with you) Look at the code date and the condition of the terminals to find a bargain! I like keeping a spare top post battery in my garage for testing/repairing 12 volt items and it comes in handy when you need to test, loan, swap or jump yourself/single women. Bigger is better. Measure and/or modify your battery tray and install the largest (physical size) battery you can get (measure height too so your hood doesn't short out your top posts. Construct a dummy battery with cardboard and tape to test your measurements.

5

OK so similar problem. The battery quit and bought a new one, everything was fine for a few days then the battery light came on, and the truck was parked at my destination (for about 10 min) when I went to go home the truck wouldn't start and I needed a jump. Just made the 5 min trip home (spitting and sputtering) and put the battery on the charger. When I went out the check 15 min later I heard a ticket-tickety sound near the back of the cab near the area of my fuel tank. The sound seemed to cycle but it also stopped if I depressed the brake pedal. I noticed the battery charged fine when the sound was NOT happening but wasn't taking a charge so well when the sound WAS happening. I took the terminals off the battery to charge it and it is charging fine now. WTF?? So is it a fuel pump short? What else could it be?

20

Probably a bad alternator (has half of normal output due to bad brushes eating into armature) and you are driving off of the battery. But check these things for 2004-2008 particularly... (may not be a problem now but they could be in the future): Check under cab, outside (under driver's door ) for a connector full of dirt with corroded connections. Wear goggles...lots of crud gets stuck there. Remove old tape and plastic loom/tubing etc. This could be creating a short particularly when wet. The alarm module behind the back-seat may be cycling and clicking relays due to dirty/muddy/corroded wires shorting under left cab (...or maybe a bad door lock actuator). Another item to check (regardless) is the fuel module under the bed. This electronic part corrodes, swells and shorts-out due to a design flaw....aluminum module mounted to steel frame/crossmember (dumb!). Located in front of spare tire... awkward spot, on left side of frame.) Pull down spare tire to inspect. Buy a new one (Dorman) on eBay. The Dorman unit is redesigned with stand-offs/feet to keep it from corroding. ALSO CONSIDER/near future: Buy a new alternator if over 150,000 miles. Alternator brushes eat into armature resulting in a 50% charge of battery. Also design flaw cracks alternator case/housing. Don't rebuild, replace. eBay $130 for 200 amp alt. Upgrade alternator with 4 gauge welding wire to alt with MEGA 200 amp fuse (Littelfuse brand)

20

ALSO: Look for damaged wiring or crispy connectors from alternator to battery. Then un- bolt and scuff/clean ground wires, (under hood, 8mm or 10mm hex heads) located on fenders and firewall. "3M Silicone Paste" is awesome stuff for electrical connectors/connections...use it on any connection. (find 3M paste on eBay or at NAPA) great for rubber parts and brake calipers too.

5

Thanks Rob will go out and check the connectors under the door -- well all the ones you suggested. The sound is coming from directly behind the back seat. At first I thought it was the sliding window (which has never worked - bought this truck used a few months ago) but as I stand next to the drivers side door near the rear of the cab front of the bed) the sound is coming from right in that area and possibly underneath, though it is hard to tell. I find it hard to believe it's the alternator - had engine (which I assume includes alternator?) and transmission replaced and just got a new battery.

5

As luck would have it, it looks like it is about to rain! (Many expletives I could say here) May have to wait until later this evening or tomorrow morning to check.

20

You're welcome! I've repaired these item on my own truck so they are worth looking at. I've done electrical work on over 8,000 vehicles as well. Could very well be the external electronic fuel module shorting out. (it's not not fuel pump) With a volt meter check for a battery drain (when the truck is not running/charging) Find a cheap volt meter are at Walmart or Harbor Freight. if battery is draining while truck is off something is shorted out (like the dirty wires or module under the bed) that might be the noise you hear!

20

You may still have the original alternator. (a new or used engine replacement doesn't guarantee an alternator) It's a fairly easy job if you tackle it yourself. Need a breaker bar to release the belt tensioner. (youtube helps)

5

My dad did all his own work and I remember helping him work on lots of vehicles. Older ones -- pre 1980. Could do it though. I really think it is (probably) the external electronic fuel module. As soon as weather cooperates I will check that first thing. I do also have a volt meter so will check for battery drain as well.

1,700

depending on what year it is,04 and up had the FPDM (fuel pump driver module mounted on the rail above your spare tire(BAD to rust out and short out the circuit board inside the module)...(they have stand-offs now on the replacement FPDM to mount them,so the metal don't touch the frame rail and rust/short out again)...check that first if it's 04 or newer,then if not,copy and paste this link and watch the video below................How to Test and Find a Parasitic Battery Drain (Key Off) - YouTube Video for parasitic battery drainâ–¶ >>>>https://www.youtube.com/watch?v=zdIKNnwEjIs<<<< post findings,and good luck!

20

Sounds familiar...

1,700

Sis65,>>>electrical gremlins are hard to find most of the time,but doable. don't go throwing parts/money at it until you find it from testing. it really sounds like you have either a short to ground(an intermittent problem,possible pinched wire)maybe from the engine/transmission replacement,or a bad FPDM,or maybe trailer wiring?more than likely nothing was wrong with your old battery or your alternator,and NO need to upgrade to anything except what came in your truck when it was new(if either of them are bad),most likely a group 65 battery and either a 95,110,or 130 amp alternator,depending on year,make,model.I have a 2000 F150 4.6L and mine has a 130 amp alternator on it from the factory.stay away from AUTOZONE for testing because they don't have a clue,PERIOD! their job is to sell you parts,and that's it! I had my battery tested there for 3 years,about every 3 months (nothing wrong with it,just wanted to know what they would say) and they told each time they tested it that it was BAD BATTERY! if you hear the fuel pump come on/prime,humm for 2 seconds when the key is turned to on,and the turns off,then it's probably not the fuel pump unless a wire is shorting to ground intermittently .if you need to test wiring under the truck,take the bed off and you can get to every wire under the truck/ on the rails behind the cab,all your EVAP components/wiring,even the fuel pump connector and wiring,unless you have a QUAD CAB,then your fuel pump would be under the back seat.

5

Oh the crud! Followed your advice Rob. Thanks!! Thought I would take it one step at a time. That connection under the door... full of dirt, gravel, dry mud. I cleaned it out and then used compressed air on it. Put it back together, hooked up the battery (which had been on the charger all night) and all good! No more tickets-tick sound, so far the battery seems to be holding a charge -- I guess I'll be back here tomorrow if it doesn't ;) Now to find a way to keep that module from collecting the crud; what do you suggest? Next I think I will change out the fuel pump module as a preventative measure before winter comes. So glad I didn't take it to a mechanic -- I'm hear what you're saying Steve -- around here they pretty much just randomly start changing out parts hoping to hit on the right one. The battery was a problem though, initially. Something I really should have checked when I bought it. Apparently the slippery used car place I bought this truck from put a car battery in it, a really small battery. I wondered why I had a hard time turning it over! One step at a time -- before long I will have a whole new truck!

20

You're welcome. Hope that was your problem. Installing a new Fuel pump driver module before the old one fails is a good idea (unless it looks like it was already replaced) When I suspected mine to be bad a couple of years ago I found it to be swollen. (and wow I just found the old pics of my garbage module in my email) You can see how it swells up and snaps (it should be perfectly flat). When the aluminum base/heat-sink distorts it snaps the circuit board under the black cover. If it looks funky like this replace it! A new revised unit should have feet/stand-offs to keep it "high-and-dry" and off of the steel bar.

1 of 1 people found this helpful.
5

Well... thought I had it licked but the (*%#$) battery light is coming on again. After testing the battery truck off and testing it running with a load it seems that it is likely the alternator. I was hoping it wasn't because I am not up to tackling this BUT I think I have someone who will do it I just have to buy the new one.

1,700

99% of the time when the battery light comes on,it's a bad alternator.what year is your truck and engine size? also with the truck running,using a volt meter,set to DC voltage,what are the readings on the battery terminals,red lead to positive,black lead to negative? you must have a FULL charge on the battery to get accurate readings doing this test,at least 12.6 VDC with engine OFF.

5

I have a Ford F150 with a 5.4L With the truck off (and a full charge on the battery) I have a 13.9. After I start it I get 12.8 and then it goes down to 12.5. Also (and I don't know if this means anything) my interior lights go out immediately when I start the truck (doors are still open) and within a minute maybe two the battery light comes on.

1,700

alternator is bad...take it off the truck,go to the ZONE and get them to test it on their machine inside the store,tell them to test it at least 3 times.it's gonna be bad..buy the alternator for your truck,or if you can wait,order it from RockAuto...still don't know what year it is,but the ZONE can hook you up if you get it there..also rent the Serpentine Belt Tool: Part number 27115 to release the tensioner so you can get the belt off the alternator(4 hands work better than 2),it's $30.00,or if you have a 1/2 inch breaker bar or ratchet with a cheater bar will work(spring on tensioner is strong,need leverage)when thru with it,take it back and they give you your money back if you rent it.

20

I pulled my old alternator apart to confirm why it was bad. (2004 F150 FX4) The brushes wear out and then eat into the armature. This one went bad at 152,000 miles. Alternator case was cracked near one of the mounting points as well. A 3/4" breaker bar or a socket wrench extended with a steel pipe will release the belt tensioner. Good time to replace tensioner pulley and other idler pulleys (very easy bolt-on job). (In the winter for F150/Expedition 4.6/5.4: If you get an annoying moaning/growling noise that sounds exactly like a noisy power steering pump it's actually a bad pulley! Sounds almost like a cat throwing-up after eating too much grass :) Replace alternator, all 4 pulleys, and belt. Tip: Do not over tighten alternator bolts... heads will snap off! Windows now run up and down very fast and volt gauge sits happy at 14 volts.

5

I have ordered all the parts and I have a guy who is going to come out and do all the work. It's not something I feel confident enough to tackle. Hopefully by the end of the week or early next week depending on how quickly I receive the parts, everything will be back up and running. Rob, you mentioned the windows...my windows have been slow, the drivers side especially. I didn't think anything of it because the drivers side window on my mother-in-law's Impala is messed up. It would work fine (sort of) in warm weather but not so great when it was cold. It needs a new motor but its something I just haven't felt like dealing with. I still drive her car (driving it right now with the truck out of commission) I'm just careful about putting the window down too far. With the truck I just assumed because of it's age it was the same thing, but maybe it's the alternator as well! I guess I will know for sure after the new one is put in.

20

You should be good to go! Consider doing the pulleys (all 4 of mine were loose/bad). A new thermostat isn't a bad idea either since it will only take 5-10 mins while everything else is out of the way. See attached pic. I did this job just a couple of weeks ago.

1,700

I have done some work on my 2000 F150 Supercab 4.6L over the years,but not a lot for the 17 year old truck.replaced the alternator a couple years ago,put one cat on it 2 months ago(rattle),put a heater core in it in 2009,rebuilt tranny in 2007(4R70W),thermostat bout a year ago,replaced fuel pump 2016(factory installed in 7/2000)it went out at 303,000 miles and lasted 16 years! upper control arm,lower ball joints(squeak,squeak,squeak)they all do it.I fixed the famous ford odometer blackout problem(couldn't see my miles(common problem)cost bout 20 cents worth of solder,and a couple hours of my time.I called local ford dealer AFTER I fixed it at 289,000 miles,and they said NO FIX,must replace instrument cluster and re-program PATS keys or truck won't start,$1400.00 they wanted to do this? fixed the shift selector for 18 cents(2 small tie wraps,thumb wheel bracket broke under dash,was off 1 position,again dealer said NO FIX,$400.00?). door locks quit working,fixed them with bout 5 cents worth of tin foil,now work like they are on steroids,bout 4 years ago).every few months,I spray my window tracks with Liquid Wrench Lubricant Silicone Spray to keep the windows working smooth,going up and down like they are on steroids! Had a boo-boo,hit from behind,got junk yard bed and rear bumper,had it painted,and that's about it,almost 335,000 miles now!

1 of 1 people found this helpful.
1,700

My 2000 F150 4.6L

1 of 1 people found this helpful.
1,700

boo boo fixed now

1,700

bed off,changing fuel pump module last year

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bed off pic

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FP MODULE LABEL!

5

I knew what I was getting into buying an older truck, but the previous owners had put a new (rebuilt) engine into it and the dealer agreed to pay for some repairs before I would buy it -- new sway bar, 4 new tires, full tune up, a couple of small cosmetic repairs. I just had the a rebuilt trans put on and the exhaust repaired (welding job) now it needs the alt. For being as old as it is it looks great! For the area that we are in where the roads are treated with chemicals in the winter, there is not a speck of rust -- which is one of the main reasons I wanted it. Everything else I looked at was rusting out underneath.

1,700

Yes,you have a very nice truck! Hopefully when you get the alternator taken care of,that will be the end of any problems...We really don't have any problems with rust,I'm 20 miles from Charlotte NC,so if a snowflake is seen,we don't go to work and no school for kids! I was in DETROIT in the 90's working at a Chrysler Plant for a service call from my company and they said we SALT the roads down WHEN NEEDED in the Winter,people go to work,kids go to school and we fix the roads in the summer time,PERIOD! most vehicles were eat up with rust,but still rolling...good luck with your truck,it's a very good looking truck.Pray for the Folks in TEXAS! it's never been that bad before,death count has went from 1 to 7 now,and people are still stranded,and it's looking like it's getting worse as I type this,MORE RAIN COMING! over 300 roads under water now,cars,trucks,HOUSES under water...now,Mandatory to leave the Houston area! now the Army Corps releases water from 2 Houston dams; thousands of homes to be affected ,not good! sorry to get off truck subject,good luck with your truck...

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