2007 Ford Expedition Alternator or electrical?

  • V8
  • FWD
  • 150,000 MILES

Truck would not start. We tried jumping but that didn't work either. Truck was towed to shop. Shop said it was battery. Replaced battery and drove truck home. Next morning truck wouldn't start. But this time it was able to start after jumping it. Drove to Advanced Auto to test starter and alternator and that tested fine. Took back to shop so they could fine the problem. They said needed to keep over night so see if it holds charge. Next morning it did not start. I was told they are not sure what the problem is but guessing it is the alternator. So they keep truck over night again to see if it is the regulator in the alternator causing the new battery to not hold a charge.

Question is: does it really take 3 days to diagnosis a problem? If the alternator tested fine then what could cause a new battery to drain over night?
Could I also be getting the run around on a issue they know nothing about?
Wouldn't they have tested this once the new battery was installed or it they put a test battery in couldn't they have tested alternator and starter to know if it was a bad battery or something else?
Please help as I feel I'm being taken for on this car repair that has no answer!

Do you
have the same problem?
Thursday, November 5th, 2015 AT 9:27 PM

1 Reply


Three days! Try three weeks of pure frustration. All vehicles for the last 20 years use WAY too much unnecessary technology and Ford is worse than many other manufacturers in that regard. You have two computers involved with blowing the horn, so the typical dead horn repair is over $800.00 instead of the 20 bucks it used to be. You can't name a system that doesn't use a computer to replace common sense. Thanks to those dozens of computers, any one can draw excessive current after the ignition switch is turned off, and you're stuck with a mechanic, (they repair mechanical things), to troubleshoot and diagnose these systems, then you're angry with us when we tell you what the bill is going to be. As a professional electronics repair technician and a master automotive technician, I have trouble diagnosing newer cars when I don't have the factory training, the manufacturer-supplied specialty equipment, and when I DO figure out the cause of the problem, the manufacturers have rigged their vehicles so I can't just stick in a used computer and send you home. I have to buy a new computer from the dealer, then have them program it to your specific vehicle. What a racket, but we're stuck with these cars. My solution is a simple one that not everyone can live with. I just "upgraded" from a rusty, trusty '88 Grand Caravan to a '94 Grand Voyager, and I let my newer vehicles sit.

Now, to address your concerns, I can't use "generator tested fine'. I need numbers to interpret. Most important is full-load output current, charging voltage, and "ripple" voltage. You can measure charging voltage yourself with an inexpensive digital voltmeter. It must be between 13.75 to 14.75 volts with the engine running. That is measured right across the two battery posts. If that is good, the rest of the tests require a professional load tester. Based on the full-load output current, I can describe in more detail if the system is working properly.

Those charging system tests only indicate whether the generator is charging the battery while you're driving. That has nothing to do with a drain on the battery after the engine is stopped. This has turned into a real mess too because it can take some computers up to 20 minutes to go to "sleep" mode. Until then, the drain on the battery will be fairly high. Special test procedures are needed too to prevent waking up those computers once they've powered down. We all learned how to test quickly for a drain and how to narrow down the cause years ago. Those test procedures are obsolete now.

Before I forget, I need to be sure you're aware that when a battery is really dead and you want to jump-start it, you usually can't just plop the cables on and start your engine. You can't get enough current through jumper cables to run a starter motor. You need to let your battery charge up relatively slowly, but if the battery was really run down, it takes ten to fifteen minutes before it will START to take a charge. It takes time for the acid in the battery to become conductive. That means leave the jumper cables, (or battery charger) on with the booster car's engine running, for a good ten minutes or more, if necessary, then try cranking your engine. Failure to wait a few minutes can make a totally dead GOOD battery appear to be defective.

The generator can cause a drain on the battery, but it's actually the voltage regulator in it. A quick test for that is to unplug the small plug on the back of the generator, then let the vehicle sit overnight. If the battery is charged the next morning each time you do that, the voltage regulator is the suspect. Problem is there are dozens, perhaps over a hundred things that can cause the same problem the same way. Most of the computers have memory circuits that are constantly drawing current from the battery. The radio is a common culprit because of its memory circuit for the station presets and clock.

As for the tests that were performed recently, if the battery tested as defective, they would have typically installed the new one and sent you on your way. Some shops will do a quick test on the charging system as a courtesy and to insure you won't have problems with their new battery, but because our test equipment, (which is expensive and becomes obsolete after two or three years), has to be paid for by someone, we have to charge for more in-depth tests. Most people will scream that we're selling products and services that aren't needed, so most of us never even bring up the subject unless there's a need for those tests. We get blamed all the time when we recommend additional tests or repairs, and we get blamed when we don't but "should have". This is why doctors perform so many unnecessary tests. It's so they don't get sued for overlooking something. Problem is, mechanics are held to much higher standards than doctors. Doctors just bury their mistakes, or you gladly run from one to another until you get a diagnosis you like. If we make a mistake the first time, we're "incompetent", or we're out to defraud you. We're also expected to keep working on the car for free until we find the source of the trouble. Try getting that kind of consideration from a doctor.

My best recommendation is to find an automotive electrical specialty shop if your mechanic can't solve this after two or three visits. I have two former students working for the premier electrical shop in my city, and that shop has a real good reputation. The problem is though, electrical problems usually aren't solved with a quick visit and simple repair. You should consider leaving the vehicle there for two weeks or longer since some tests take just a few minutes, but they have to be done periodically over a longer period of time. This would equate to your staying in a hospital so they can run tests every few hours, rather than making you run back every day for an hour.

I know I sound crabby about this subject, but I am. This technology has been forced on us and you're paying for it now. You need to put the blame on Ford, not your mechanic. As far back as the mid '90s some minivans had over two miles of wire to go between all those computers, and the moisture, dirt, and vibration found in cars is the worst possible environment to put electronics in. Wires can rub through and short out, and connectors have terminals that can corrode. You can plan on a lot more electrical problems, just like all our other customers.

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Thursday, November 5th, 2015 AT 11:00 PM

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