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  1. #1

    Default 88 Turbo Bird Over Charging

    1988 Turbo Coup is over charging, I have tried several Alternators, batteries and grounded the alternator directly to the fender apron, and it is still over charging. On start up the charge is 12.4v - 12.8v at a direct alternator check, bring the car up to 3,000rpm and the charge goes to well over what my gauge can register(est 18v-20v) this over charging will cut the spark and kill the car. I need help, this has made the car in-drivable, really hate to see it sit.

  2. #2

  3. #3

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    I'm old and forgetful but on the turbo coupe is the voltage regulator on the fender or on the alternator? That sure sounds like the ptoblem. I would recommend connecting jumper cables between the battery and the alternator so that you can be sure that both the engine grounds and positive connections to the alternator aren't a factor in ma king the voltage regulator have an uncorrect assesment of the load. The other thought would be to pull all fuses and see if that changes anything. I doubt it will but troubleshooting and looking for clues is key.

  4. #4

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    Test it with a good known meter.

    The irv in the dash can go bad and cause the gauges to read really high. If any other gauge (like gas gauge) also reads higher, then I'd not worry about it. This can also be caused by a bad ignition switch contact.

    Also if I am not mistaken, it should be an amp gauge not a voltage gauge.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  5. #5

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    It is a stock pulley, I also grounded the alternator directly to the battery this morning(still no change) and I did not look at the gauge in the car, I used a hand held meter on the hot stud and grounded to the engine hook at the valve cover. And the voltage regulator is in the alternator. Also pulled all the fuses with still no affect.

  6. #6

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    There is really a limited number of things that it could be. Either the regulator is working but doesn't see the true voltage of the battery because a cable is corroded or connection is bad and/or it is overcharging because the regulator is bad. What voltage do you get when you measure the voltage on the alternator post / case?

  7. #7

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    At the post/case the voltage is reading 12.2v-12.8v, if the car is revved to 3,000rpm the voltage output is 15v-18v. The voltage does not return to 12v at idle after revving it stays at 15v-18v. The battery cables are new, all ground wires have been checked and cleaned due to a leaky oil pan. I have also cleaned the plug leading to the alternator.

  8. #8
    FEP Power Member
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    I’m not an expert but I believe you are discussing a 2G alternator model. A quick look at some wiring diagrams suggests a fuse link on the yellow wire might be open. Likely you will find it on the battery side of the starter solenoid attached by a ring terminal. Look for a molded bulge (fuse link) in the wire probably with 6-8” of the ring terminal. Again this is a guess without being able to see it.

    Otherwise there could be a strange problem such as a short in the battery. Not running, the battery should always be about 12 volts.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert, 92 GT Vert.
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    15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  9. #9

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    I will check for the fuse link on the solenoid, this is the third battery(Duralast, Bull Dog, and NAPA Gold) Bad solenoid?

  10. #10

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    Pretty much has to be the regulator. A bad fuseable link on the charge circuit wouldnt charge the battery at all.

    Throw an alternator at it and be done.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  11. #11

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    The fusible link was deteriorating, so I pulled, stripped, soldiered, and heat shrinked the bundle. But did not fix the issue so it is going to be a new alternator. Is Bosh a good option?

  12. #12

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    I'm the wrong guy to ask. If picked alternator up out of mud puddles at the junk yard and ran that for years before.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  13. #13

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    It's a crap shoot if you are going the reman/rebuilt route. I usually go with whatever has a lifetime warranty. Bosch are usually not available in store around here so I have no experience with them.
    '89 XR-7 5 Speed
    '95 SC 5 Speed
    '91 Crown Vic P72 351W
    '95 Saturn SW2
    '85 Ford LTD Squire

  14. #14
    FEP Super Member gr79's Avatar
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    Default

    Bosch is a oem company. Aftermarket quality? May be different.
    Went with Bosch a while back. Wanted the best for reliability of my truck.
    Had 2 Bosch lifetime starters in 2 years from Oreallys. 3rd is their Ultima house brand.
    Has outlasted the Bosch they no longer carry.
    Same thing happened with the Mustang.

    Alternative: Local rebuilder who does nothing but starters and alternators.

  15. #15

    Default

    Let's try a bit more targeted approach -

    Original equipment alternators do not regulate to the voltage seen at the alternator output stud, they regulate
    to a remote sense point in the harness. If the regulator cannot see any voltage at the remote sense point, the
    alternator will be commanded to full charge.

    On a 2G alternator, the regulator connector shell should be marked 'A' 'S' and 'I'. Pierce the wire going to the 'A'
    terminal with a straight pin, and measure the voltage on it. That will be what the alternator thinks is the voltage
    on the rest of the car's electrical system.

    If your alternator has a generic regulator with no markings, use this pinout -

    Name:  Ford3G.jpg
Views: 53
Size:  31.7 KB
    Last edited by JACook; 12-07-2017 at 05:57 PM.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ... '68 Vert, Mexican block 307 4-speed...
    '71 Datsun 510 ... And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  16. #16

    Default

    I've had the alternator rebuilt and gone over but the problem was not fixed, the replacement regulator was wrong so that was swapped for an OEM replacement from another alternator but to no avail. Going to try the Bosch

  17. #17

    Default

    Quote Originally Posted by JACook View Post
    Let's try a bit more targeted approach -

    Original equipment alternators do not regulate to the voltage seen at the alternator output stud, they regulate
    to a remote sense point in the harness. If the regulator cannot see any voltage at the remote sense point, the
    alternator will be commanded to full charge.

    On a 2G alternator, the regulator connector shell should be marked 'A' 'S' and 'I'. Pierce the wire going to the 'A'
    terminal with a straight pin, and measure the voltage on it. That will be what the alternator thinks is the voltage
    on the rest of the car's electrical system.

    If your alternator has a generic regulator with no markings, use this pinout -

    Name:  Ford3G.jpg
Views: 53
Size:  31.7 KB
    This is a very good post.

    One thing I forgot about, the turbo birds have a cluster with an amp gauge so there is a shunt in the mix somewhere to make that work. There could be a wiring or voltage cable issue between that somewhere.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  18. #18
    FEP Power Member
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    Default

    Quote Originally Posted by JACook View Post
    Let's try a bit more targeted approach -

    Original equipment alternators do not regulate to the voltage seen at the alternator output stud, they regulate
    to a remote sense point in the harness. If the regulator cannot see any voltage at the remote sense point, the
    alternator will be commanded to full charge.

    On a 2G alternator, the regulator connector shell should be marked 'A' 'S' and 'I'. Pierce the wire going to the 'A'
    terminal with a straight pin, and measure the voltage on it. That will be what the alternator thinks is the voltage
    on the rest of the car's electrical system.

    If your alternator has a generic regulator with no markings, use this pinout -

    Name:  Ford3G.jpg
Views: 53
Size:  31.7 KB
    I believe this I s the yellow wire with the fuse link I suggested to check. Yes, it would have been wise to measure the voltage at the alternator first.

    As for Amp gauges, they display charging and or over charging. If the circuit was open, it’s more likely not to charge. I could be wrong as I have not checked the drawing.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert, 92 GT Vert.
    03 Mach 1 7900 miles, 69 Mustang, 67 Mustang, 14 Mustang CS/GT,
    15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  19. #19

    Default

    What will keep it from charging is if there's no voltage at the 'S' terminal (Fords with ammeters or voltmeters) or
    the 'I' terminal (Fords with 'ALT' lights). That voltage is the alternator 'turn on' signal. The 'A' terminal does not
    have to have any voltage on it for charging to happen, but it does if you want the alternator to know when to stop
    charging.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ... '68 Vert, Mexican block 307 4-speed...
    '71 Datsun 510 ... And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  20. #20

    Default

    I don't think anyone has mentioned this but I think the turbocoupe's came with a Mitsubishi alternator. It was higher output than the 2g's. But that still shouldn't cause this problem

  21. #21

    Default

    I have looked at the fuse link(yellow bundle) wire was pulled slightly but that was fixed, I also checked the wires that are in the bundle as well but they were fine(no cuts or burns) the replacement alternator that I ordered is on back order, so not getting it for another week but when it comes in I will give an update as to the running condition of the Bird. It was a Mitsubishi alternator on the car when I got it, but the hot terminal was burned slightly due to the previous owner trying to replace the distributer.

  22. #22

    Default

    And I will also look at the "A" lead going to the alternator to find what the voltage is.

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