504 alternator death
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  1. #1
    Fellow Frogger!
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    Default 504 alternator death

    The Bosch 40A alternator [external voltage regulator] has died. Amongst my spares I had 2 spares, one of which was unable to be mounted correctly. I fitted the other, a Motorola 70? amp model with an internal regulator. Car started and ran well and the gauge on the dash moved up a bit but not into the black. [Battery has been on charger for 2 days and appears fine despite approaching its 9th birthday! The real problem was that I couldn't turn the bloody engine off! A wiring issue obviously. Alt.1 [dead one] has:B+ ,heavy red to starter; DF flat blade grey wire to external reg; D- brown wire to reg. and it appears to be just an earth to the alt body.
    Alt.2 which I suspect is ex 505 of some sort has B+, the heavy red wire must go here. D+goes to a Falcon 2022 [suppressor?] and out of this comes another wire with a flat blade which I connected to the grey wire. This left the brown wire hanging with nowhere to connect. I started car no problem and the gauge did move up to nearly the black but not all the way. My digital volt metre says it is putting out 14+ volts. I turned it off and nothing happened! I shorted the brown wire to the alternator body and the engine did stop with the key off. Clearly this wire goes somewhere.
    Any help please on the wiring for changing from external to internal regulators .Thanks ,Neil

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  2. #2
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by neil s View Post
    The Bosch 40A alternator [external voltage regulator] has died. Amongst my spares I had 2 spares, one of which was unable to be mounted correctly. I fitted the other, a Motorola 70? amp model with an internal regulator. Car started and ran well and the gauge on the dash moved up a bit but not into the black. [Battery has been on charger for 2 days and appears fine despite approaching its 9th birthday! The real problem was that I couldn't turn the bloody engine off! A wiring issue obviously. Alt.1 [dead one] has:B+ ,heavy red to starter; DF flat blade grey wire to external reg; D- brown wire to reg. and it appears to be just an earth to the alt body.
    Alt.2 which I suspect is ex 505 of some sort has B+, the heavy red wire must go here. D+goes to a Falcon 2022 [suppressor?] and out of this comes another wire with a flat blade which I connected to the grey wire. This left the brown wire hanging with nowhere to connect. I started car no problem and the gauge did move up to nearly the black but not all the way. My digital volt metre says it is putting out 14+ volts. I turned it off and nothing happened! I shorted the brown wire to the alternator body and the engine did stop with the key off. Clearly this wire goes somewhere.
    Any help please on the wiring for changing from external to internal regulators .Thanks ,Neil

    Basic alternators with an internal regulator generally have two terminals. A M6 stud which is the output, connect directly to the battery. Then there is smaller terminal, sometimes marked D+, F, exc, ind, or similar.

    This is needs to be connected to ignition switched 12+v via 3 watt 12 volt lamp. When the alternator is not charging the lamp is lit. Once the alternator is charging the lamp extinguishes.

    If you hook up 12v+ directly to the exc terminal the alternator will charge, but the alternator will back feed the ignition cct and make the engine impossible turn off. The lamp as above limits the current, kills the alternator charging and lets the engine stop.

    You don't need a lamp, simply use a IN4004 (400V 1 A ) diode in series with the exc terminal, the "bar" should point to alternator. The diode blocks the back feed.

    Late model Bosch alternators with voltage sense et al are entirely different again. This style of alternator has a plug like a fuel injector on it. I have a separate thread on how to wire this type of alternator.

    The 504 has two wires from the alternator to the regulator at firewall.

    One is earth (ring terminals both ends?).
    The other is field (QC both ends), just join this wire up to 12v+ ignition switched (the 3rd wire at the regulator)
    Ignore earth wire or connect the earth at the alternator. (It's not needed on an internal reg)

    EDIT: Consider fitting a late model Bosch alternator with "voltage sense". It will transform the 504 electrical system with regulated 14 volts. Faster flashers, voltmeter reads properly, brighter headlights, heater fan works better etc etc.

    I'll try to find the thread...
    gererator to alternator conversion.......
    There is a pdf with a printable circuit diagram in the thread.

    Holden VT Bosch alternators are so cheap , around $30 at the DIY wreckers.
    Last edited by robmac; 20th August 2014 at 08:25 PM.

  3. #3
    Fellow Frogger! Uffee's Avatar
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    Quote Originally Posted by robmac View Post
    Holden VT Bosch alternators are so cheap , around $30 at the DIY wreckers.
    $38 from Upullit in SA. I just fitted one to my wife's Triumph 2500S. I did have to hunt around for one that hadn't had the regulator (~$70 brand new) nicked though.

    Instead of choosing one of: windscreen wipers, demister, lights etc, I can now put all of them on. I turned on absolutely everything electrical I could at idle and the voltage doesn't go any lower than 13.4 Volts.

    Just be careful not to confuse S (sense) and L (lamp), the regulator will still work but the warning light won't.
    504 GL Coupe '73 Silver
    504 GTDT Pickup Mini-Motorhome '83 Coral Red
    407 HDi Sedan '05

  4. #4
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    Thanks, Rob. Up and running with the Motorola alternator [70?amp] putting out a steady 14 -14.1 volts. The electrics don't know what has hit them! For the light I simply used a 504 dash light and fitting from a spare instrument panel I have and soldered the wires to it. Cost zero. If this one dies I will go down the VT route suggested although I have also seen that a Magna one fits and works as well. Why have we all persisted with crappy 40 A alternators for 40 years when the solution is so cheap and easy? Thanks again. Neil

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    Looks like something to consider for my car . Does the dash gauge still work with this procedure or does a light replace it ? .The gauge on mine always read low [usually in the red] but the output was ok at 13 to 14 volts .I changed the gauge with one from a spare inst panel and the readings are now up in the normal zone .I never drive in the rain and seldom at night ,so the most I have on at the same time are brake lights and indicators .
    Last edited by julian b; 22nd August 2014 at 05:28 PM.

  6. #6
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by julian b View Post
    Looks like something to consider for my car . Does the dash gauge still work with this procedure or does a light replace it ? .The gauge on mine always read low [usually in the red] but the output was ok at 13 to 14 volts .I changed the gauge with one from a spare inst panel and the readings are now up in the normal zone .
    Julian,

    The voltmeter will work, except now it will read in the middle of the range because the system voltage is running at a sensible level.

    In my opinion the original Bosch alternator, with external reg, should be pensioned the first time the bonnet is opened!.

    Every one who fits a decent alternator is pleased with the outcome and wonders why it wasn't done sooner.

    If you need to purchase an alternator the VT Holden unit is the best, albeit a bit complicated way to go. Using the current sense feature is really worthwhile.


    Neil,

    I believe the Magna alternators are the sqat type? These are good too. The have more current available at lower alternator revs.

    Great if have electric cooling fans or air conditioning. Because they will maintain charge even if the engine is at an idle.

    I've used KR Verada (the luxury electric everything model) alternators rated at 120amps on competition vehicles. But they are big and heavy and need poly Vee drive belt.
    Last edited by robmac; 22nd August 2014 at 05:39 PM.

  7. #7
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    Yes the voltmeter still works but is barely in the black even though it is charging at 14v. It could be the 9 year old battery here (touch wood) though.The light is under the bonnet and I think only works if the alternator fails to charge.

  8. #8
    BGJ
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    Hi all:

    I know this is an old thread, but I thought it might be better to open it back up than to start an new one. I have a 1979 504 GL, which was fitted with a 35A Bosch alternator and external regulator. I recently acquired a new Valeo 50A, internally regulated unit to fit. I've tried to understand the instructions here, and have searched numerous other threads, but just can't quite get my head around how this new part needs to be wired.

    The old wiring was: Large red wire (to starter) on terminal B+, small brown wire (to regulator—earth?) on D-, small grey wire (also to regulator) on a spade to DF. There was a also a capacitor (I think?) running between D- and B +.

    If I wire up the new alternator the same way, with or without the capacitor (?) across the two terminals, the engine will start but the ignition switch won't turn it off. So far, the same as neil s. The only other thing to note is that the new part came with what I think is a resistor, marked 82ohms, ROP2, 5%P7: I've no idea what this is for.

    So, to wire up properly: I take it I need to solder inline either a diode or 3w lamp in the small grey wire, but what about the other end (at the regulator box)? Do I need to bypass this?

    I can see that robmac has probably answered my question, but I just don't fully understand how to execute his instructions...

    Many thanks in advance!

  9. #9
    Fellow Frogger! Doush_504's Avatar
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    Quote Originally Posted by robmac View Post
    EDIT: Consider fitting a late model Bosch alternator with "voltage sense". It will transform the 504 electrical system with regulated 14 volts. Faster flashers, voltmeter reads properly, brighter headlights, heater fan works better etc etc.
    Robmac
    Is there a way to recognize it if sold separately ?
    Chadi

    1982 504 SR white manual sedan with A/C (257 000 Km)
    2012 308 1.6 VTi Vapor Grey manual H/B (35000 Km)
    1994 405 1.6 white manual sedan (208 000 Km)
    1992 605 SV24 (91 000 Km)
    2005 406 2.0L automatic (Replaced with a 2013 C5)
    1983 505 GR white manual sedan with A/C (170000 Km)

    All since new


  10. #10
    BGJ
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    Update:

    I placed the IN 4004 diode inline as robmac suggested, and everything appears to work as it should with the old regulator still in place.

    I guess I'll assume all is well! Thanks for the info here.

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