Battery or alternator

Or something else?

2003 F150 8 cyl. 5.4 L

Driving home, the red battery ion appeared in the dash. I didn't really notice any problems with how it drove and I made it home ok.

Driving back (20 minutes), I really didn't notice anything but the ABS and red battery icon appeared.

Driving home (20 minutes), the radio was intermittent. The radio went off altogether. The truck began "missing" or running poorly. I made it home, parked, turned off the engine, tried to turn it over, and it made the dreaded clicking sound.

Any help appreciated!

Mike

Reply to
Michael
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otice any problems with how it drove and I made it home ok.

d red battery icon appeared.

altogether. The truck began "missing" or running poorly. I made it home, p arked, turned off the engine, tried to turn it over, and it made the dreade d clicking sound.

First, charge up the battery. Make sure all the connections are sound. Chec k the voltage - it should be over 12.4V. If it's not, it's your battery. St art the engine. If it's not over 13.6V or so, it's your alternator. If it's 15V or above, you're overcharging the battery. Replace the regulator or al ternator. Mostly, it sounds like your alternator is the problem. Make sure all the connections to the alternator are OK.

Reply to
dsi1

Easy to test. Get a cheap voltmeter. (even the free HF units will work for this) Hook the meter up to the battery posts with it set to DC voltage and read the voltage. Jump start or charge the battery till the truck will start.

With the engine running you should see a voltage at the battery posts rise to close to 14-15 volts if the alternator is working. If the voltage doesn't rise the alternator MAY be bad.

Check fuse number 11 (20 amp) in the junction box under the hood. If it blows or corrodes the alternator will stop working.

Also check the battery cables, the connections on the starter relay and the connections on the alternator. Wiggle them around while watching the meter. If the wires corrode internally they could cause this as well.

Reply to
Steve W.

Michael: Historically, alternators have failed mor frequently than have batteries.

Reply to
thekmanrocks

Hi Steve,

Thanks for your help! I jumped the truck and checked the voltage. It start ed out at 14 and then slowly leaked down to nothing. I then switched the 11 fuse with another 20 amp fuse and tried again, but I got the same result. Wiggled the wires to no effect. It sounds like the alternator.

Mike

Reply to
Michael

If you want to be sure, remove the battery that's in it and connect up one that is charged. (you can do that with jumper cables if needed) Then start it and check the voltage at the battery. I'm suspicious of the initial 14 volt reading dropping to zero. That sounds more like a bad battery. Or it may be that you have both a bad alternator and as a result a bad battery. (A shorted diode in the alternator could do that)

Or just pull the alternator and take it in, many parts stores will test them free.

Reply to
Steve W.

Here's a question. My other car is a Toyota Highlander. If I bypass the bat tery on my truck and try to start it with cables from the post to the batte ry of the Highlander to check the voltage, will this harm anything? I under stand it might not have enough power to crank my truck. I just don't want t o mess anything up.

Thanks,

Mike

Reply to
Michael

Voltage went to zero? I suspect his volt meter connection went bad, as in no connection. I have a 12V battery which was made in 2001. It 'died' in 2007. It has been sitting 'dead' for 8.7 years. I just measured it's voltage... it's producing 4.27 volts! Wiggle your voltmeter connections to get a good connection. Keep wiggling them now and again.

Reply to
M.A. Stewart

But if it's a bad battery, wouldn't the car continue to run? While it's running, I watch the voltage meter start at 12 today and slowly leak to nothing.

Thanks,

Mike

Reply to
Michael

Not if the bad battery killed the alternator because it has shorted plates inside.

However this new 12 volt starting voltage you posted should rule that out.

Reply to
Steve W.

I'm taking the alternator out today and taking to the parts store to get it tested, just to be sure. If the alternator is bad, should I buy a new battery too? I'm thinking yes.

Thanks!

Mike

Reply to
Michael

As I was moving the wire harness out of the way to get to the bolts on the alternator, one of the wires to the alternator was so corroded it pulled right out of the clip. I hope that's the problem.

Mike

Reply to
Michael

Congratulations!! You found yer problem (one of them anyways)! Repair the wire. Charge yer battery. Start it up and see what happens! Report back.

Reply to
M.A. Stewart

What he said. Especially the report back.

Reply to
Steve W.

I took off the alternator and had it bench tested at Autozone. It failed. I bought a new one and installed it and got a nice steady 14.5 reading on my multimeter. Also, the truck seems to have a little more zip.

However, the corroded wire was the Stator plug for the dashboard warning an d also (apparently) the radio/mp3 player. The Stator wire and connector are pretty shot. I'll need to find/manufacture some kind of replacement. I tap ed it off but I can't listen to Brad Paisley for a while.

Reply to
Michael

Fix the connector before you drive it. You can get the repair parts at most good parts stores. If you don't have power inside the vehicle that isn't just the idiot light connector. It also is part of the regulation circuit and tells the alternator that the load that it needs to keep up with. With it unhooked you could end up with a dead battery and another failed alternator.

Reply to
Steve W.

I'm not having luck with Autozone or O'Reilly's for the stator plug. The closest I can find is this:

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Reply to
Michael

You don't buy the plug, you buy the replacement contact and keep the existing body. Be sure to use the correct crimp tool on the contact; a tool for insulated crimp lugs is not the correct one.

--scott

Reply to
Scott Dorsey

I pulled out the contact and tried to re-work it with no luck. Wouldn't the contact be even more difficult to find?

Merci,

Mike

Reply to
Michael

Take the whole thing to an actual locally-owned auto parts store with clueful people behind the counter. Not a chain, but some place that deals with local shops. You'll find that manufacturers use the same contacts for all sorts of different connectors.

--scott

Reply to
Scott Dorsey

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