CX No Volts going to Engine Coils
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Thread: CX No Volts going to Engine Coils

  1. #1
    Tadpole
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    Default CX No Volts going to Engine Coils

    Hi all.
    Ive recently checked to see if the coils in my 85' series 1 CX are receiving volts. It turns out that only 2 out of the 4 positive terminals on the coils are receiving volts. Does anyone have an idea why this may be happening?
    Cheers, Moe.

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  2. #2
    Tadpole
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    I'm confused by 'two of the four positive terminals'. If you've got a solid-state system (AEI, two coils, no distributor) then the connector to each coil will have three pins which actually cover two electrical connections (there's an extra pin to connect a capacitor to ground). In terms of the electrical connections, one end of each coil is connected to positive & the other is momentarily connected to ground by the AEI when it wants a spark.

    Primary coil resistance (measured across the coil with the connector removed) should be about 2 ohms (give or take - it depends on which type of coil you have installed).

    If the primary coils are ok then check the connectors (common source of problems what with corrosion & arcing due to high currents). Then systematically work back upstream. From memory, there is a connector somewhere that connects the positive voltage supply between the coils - that could well be your problem (and would explain why one coil has power when the other doesn't).

    Good luck!

  3. #3
    Real cars have hydraulics DoubleChevron's Avatar
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    Yeah, two of the 4pin is what it should have .................................
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  4. #4
    Tadpole
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    Ah - I stand corrected. What are the four pins for then (seems overkill for a single primary coil..?)

  5. #5
    Real cars have hydraulics DoubleChevron's Avatar
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    from memory only 3 have wires into them... so you'll have the earth through the AEI, the 12volts for the coil and probably 12volts for the capacitor. wasted spark, so each coil will fire on cylinder on its compression stroke, and the other on its exhaust stroke.
    'Cit' homepage:
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    Proper cars--
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    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
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  6. #6
    Tadpole
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    Sorry for the confusion eddief, I'm new to a lot of this lingo. But yes it is a solid state system and each coil does have 3 connector pins.

    So Double Chevron if I understand you correctly, only 1 of the two non-ground pins on each coil should have 12 volts? So there is no problem?

    And i should Should disconnect the coils and test to see whether they have roughly two ohms of resistance?

    Cheers, Moe.

  7. #7
    Tadpole
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    Sorry for the confusion eddief, I'm new to a lot of this lingo. But yes it is a solid state system and each coil does have 3 connector pins.

    So Double Chevron if I understand you correctly, only 1 of the two non-ground pins on each coil should have 12 volts? So there is no problem?

    And i should Should disconnect the coils and test to see whether they have roughly two ohms of resistance?

    Cheers, Moe.

  8. #8
    Tadpole
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    Hi,
    In the twin coil arrangement the capacitor is internally connected to the 12v terminal and is there to suppress spikes that may interfere with other electronics and the car radio.

    The coil primary winding should have typically around 2 ohms resistance, if you disconnect the coil plug from the AEI unit WITH THE IGNITION OFF then switch on the ignition you should find 12v on the coil AEI terminals.

    The high voltage for the spark is provided by a collapsing magnetic field in the coils magnetic core in other words switch off not switch on, the same thing occurs with a conventional coil system the spark occurs when the points open not close.

    In electronic systems the coil primary currents are considerably higher than in a points system ( say 6-7 amps instead of 3 or 4 ) and good primary connections are essential.

    Hope this helps a little.
    Marion likes this.

  9. #9
    Tadpole
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    Apologies for the lack of input - I was away in Sweden for a VERY cold, long weekend. Now back in UK & happy to offer advice if required.
    Marion likes this.

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