Odd charging issue. Help please.

Discussion in '2005+ Mustang GT 4.6L Tech' started by Blue Roads, Mar 11, 2019.

  1. Blue Roads

    Blue Roads Junior Member

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    I'm putting the backstory on this in case anyone has seen anything that may tie these things together. I've been patient, understanding that a 10 year old car is going to have issues, but I'm now at the point where I seriously regret buying it.

    I've got a 2008 GT, automatic, stock.

    Jan 24, 2019, I bought the car from Carmax.

    Feb 2, just over a week later, the check engine light comes on. It's code P0155, O2 sensor. I take it back to Carmax. They put an O2 sensor in it, claim it was a bad one and they needed a Ford OEM sensor, which still doesn't fix it, so they send it to the Ford dealership, who claims they put the wrong O2 sensor in it, which still doesn't fix the CEL. They conclude that the PCM needs to be replaced, and it takes them until March 1 to do all this diagnosis, approve the new PCM, and have Ford put it in the car. I pick up the car on March 1.

    March 2, ONE DAY LATER, I'm driving home and the battery gauge (I'm guessing it's a volt meter) starts to drop, and a block from my house the gauge turns red since it hits bottom and odd lights are coming on in the gauges, the ABS light and traction control light, along with the battery light. The radio was off but came on and reset itself, and the CD changer started clicking. I turned off the headlights and pulled the parking brake while I was sitting at the red light, and that brought the gauge back up where it should be. I got home and checked the battery voltage with the car off, 11.5V. It sitll managed to start the car. With the car running, 11.0V. I charge the battery and on Monday morning, March 4, I take it back to Carmax. They replace the alternator and battery, and I picked it up yesterday, March 8.

    Today, ONE DAY LATER, while getting on the highway, I gave it a good bit of throttle and the ABS and traction control lights came on in the gauges again. They turned back off when I let off the throttle. I noticed it continuing to do this, and found that anything over 2000 RPM would cause those lights to come on along with the battery light, and would peg the battery meter all the way to full. Later in the evening I was driving and it happened consistently over 2000 RPM, and if it stayed there for more than a few seconds, the interior lights would turn off, but my headlights would remain lit. Once the RPM dropped, the interior lights would come back on. The fog lights would also turn off when this happened, and the radio has reset itself again.

    I've heard about the 2010 alternators being a better 3-phase design, but I'm not sure what got put into this car for a replacement alternator. I'm thinking it's the original spec single phase alternator, if I read other posts correctly as to how it came from the factory.

    I've attached pictures of the well under the passenger side windshield cowl, and the SJB. Looks to be OK from what I can see.

    Any thoughts? Has anyone experienced stuff like this? I'm taking it back to the dealer on Monday morning.

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  2. msvela448

    msvela448 forum member

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  3. brford

    brford Junior Member

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    You should check the two cables that are attached via connectors with bolts to the left (passenger) side of the radiator support. I'd suggest removing the bolts, making sure that the cables are well connected to the interlock washer that the bolt goes through. Make sure that washer is making good contact to the radiator support. These cables ground the charging system. In the event of a front accident they break off or disconnect and disable the electrical system.
     
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  4. Blue Roads

    Blue Roads Junior Member

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    Thanks for the info!

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  5. Blue Roads

    Blue Roads Junior Member

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    Thanks again for the referral to Department of Boost. If the dealer will approve it and it won't hurt my warranty and extended service, I'm going to get one of their alternators and have it installed since it's getting done under warranty.
     
  6. msvela448

    msvela448 forum member

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    Good deal... Those are really nice alternators, and the price is good too.

    I hope it solves your problems.

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  7. 406guy

    406guy Junior Member

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    Do you know the part number of the Denso plug and play replacement? I am also interested in this.
     
  8. Blue Roads

    Blue Roads Junior Member

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    I went to the Department of Boost Facebook page and got the owner Jason's email there. I emailed him and he responded right away. Very helpful. It turned out I didn't need to buy one from him, as the dealer replaced my alternator under warranty. As soon as I need an upgrade I'll be contacting Jason again.
     
  9. msvela448

    msvela448 forum member

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    The Motorcraft GL950 is the stock Denso unit Ford Part # 9R3Z10346B. This one is with the clutched pulley for manual cars. The one without the clutched pulley for automatic cars is the GL960 (9R3Z10346D).

    But the ones from Department of Boost are upgraded and powder coated. He will also do 8-rib versions if you need that.

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  10. msvela448

    msvela448 forum member

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    Did the new alternator fix the issue?

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  11. Blue Roads

    Blue Roads Junior Member

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    So far it has been good. I'll keep you posted.
     
  12. Blue Roads

    Blue Roads Junior Member

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    My alternator from March lasted until a couple of weeks ago. Now I have an intermittent "Check charging system" and battery light, which I hear is a possible diode failure in the alternator. The dealership's warranty on the work is 6 months, and it failed 7 months later. It's not draining the battery so it's not critical yet, but still a pain.
     
  13. msvela448

    msvela448 forum member

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    Sounds like it's time for a Denso from Department of Boost.

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  14. 07 Boss

    07 Boss Senior Member

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    You should go ahead and replace it now as when it goes I bet it will be at the most inconvenient time.
     
  15. Blue Roads

    Blue Roads Junior Member

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    That's what I figured, and it's in the shop now. They replaced it under warranty, and it was also squeaking when I would start rolling from a stop, so they're also doing the trailing arm bushings.
     
  16. Blue Roads

    Blue Roads Junior Member

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    That is my plan, if it fails outside of warranty. I won't know how to act, not planning for an alternator failure once I get one.
     
  17. james432

    james432 forum member

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    Department of boost is what Iam about to order next week I just emailed them.So this is the best one we can get for are cars??


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  18. DieHarder

    DieHarder Junior Member

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    My recommendation is to add a ground cable (4 or even 2 gauge) from the ground on the passenger strut tower and route it to one of the lugs that hold the alternator down to ensure it is at ground potential. The alternator charging systems are computer controlled but will not charge correctly if you have a ground issue (you'll often see 11.5v or thereabouts output instead of at least 13.5v on the alternator output post) even though the alternator is good. The reason is because you may have floating grounds. Floating grounds will cause all kinds of mayhem in these cars. The grounds on these cars are notorious for becoming corroded so being 10 years old it's likely that may be your problem (or at least one of them). You can either identify and clean each and every ground on the car and tighten them back down or the easier fix as I've described is purchasing some good copper cable at your local hardware store (including a couple of lugs; get ones big enough that will fit tight on the cable and big enough that the mounting bolts will go through); cut to length, crimp the ends (use a punch and hammer if necessary) and run it from a good ground to an alternator mounting bolt.

    I chased this problem for weeks before I finally verified the problem by adding a temp ground from the strut ground to the body of the alternator and suddenly, everything worked as it should. And I was already using one of Jason's alternators.

    I'll post a pic once I figure out how....
     
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  19. DieHarder

    DieHarder Junior Member

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    To ensure the alternator body is at ground potential (the alternator must be at ground for the charge circuit to output the proper voltage) run a new ground from the passenger strut tower (same tab that battery ground uses) and run the cable to a mounting bolt on the alternator. See if that doesn't improve the charging of the alternator.
     
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