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Coil Powering Both Sides


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#1 _mini1000_

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Posted 26 November 2011 - 01:45 PM

hi guys, im having trouble with the wiring, from what i susspect is due to the coil
i currently have the coil set up as follows
red wire coming from accuspark electronice ignition module in distributor -> coil +
black wire coming from accuspark electronic ignition module in distributor -> white wire/black tracer -> coil -
white wire in loom -> coil +

when i test the coil with a circuit tester, i am getting power to both the positive and negative terminals of the coil
when i earth the negative terminal against the body etc, the coil body becomes powered

has anyone any ideas as to why i have power in both terminals?
thanks

#2 MiniElliott

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Posted 26 November 2011 - 02:33 PM

I carnt tell you why both terminals have power, but I can say that my engine runs fine and the coil has 12 volts at the negative and positive terminals. I was puzzled too when looking at the multimeter but the car runs fine.

#3 mini13

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Posted 26 November 2011 - 02:44 PM

one side of the coil is powered, and it then passes through the oil to the other side.

the distributor then operates the points (or in your case accuspark module) which pulls the negative side down to 0v, holds it there for a short while then releases it creating the spark.

this happens once for each spark, so a lot of times a second, if you measure the voltage on the negaive side of the coil when the engine is running youre likly to see about 6 v.

#4 _mini1000_

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Posted 26 November 2011 - 02:47 PM

im getting power through the earth wire for the ignition light in the dash. when left untouched, the light doesnt come on with the ignition. when earthed (brown/yellow wire), it lights up. this wire is also recieveing power going into the alternator
when the indicators are on, they work as they should however when i turn the headlights on, they just glow steady.
hazzards lights flick fast and dim so im guessing these problems are all down to the power going through the negative of the coil?
im even getting earth going through the negative of the distributor

all the earth straps are working correctly as ive run jump leads from the battery earth to each earth strap and all is as it should


@mini13 so both sides of the coil should be recieving power when the ignition is in position1/2 (engine off) or only when the engine is running?

#5 dklawson

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Posted 27 November 2011 - 04:22 PM

You are combining different circuits in this discussion. Circuits that have nothing to do with each other.

1) Coil Voltage
Yes, if the points are open and/or the electronic module is NOT CLOSED then you will measure battery voltage on both the coil (+) and coil(-) terminals. Since there is no current flowing through the coil (no path to earth) then both sides of the coil will be at the same potential. When the points close (or the module closes/conducts) you establish an earth path and the coil (-) terminal goes to earth potential (0V).

2) Ignition Light
That lamp's name has always caused confusion. The lamp has nothing to do with the ignition system, it has to do with the alternator as you noted. A better name for that lamp would be "Charge Warning Lamp". The circuit works like this: White wire from the ignition switch to one side of the warning lamp. Brown/yellow wire from the other side of the lamp to the small terminal on the alternator. The small terminal on the alternator is connected internally to the alternator field coils. The field coils are connected on their other end to earth. Thus, when you turn the key to "run", the warning lamp should come "on" as current flows through the lamp,through the alternator field coils, and finally to earth. When the alternator starts making electricity, it brings (internally) the small terminal up to the charging voltage. When that happens, both ends of the warning light wiring are at the same voltage (charge voltage) so the lamp goes "out". So, anytime you see that light "on" with the engine running it means the alternator is not making electricity.

3) Hazards and Headlights.
Hazards and headlights are powered on a circuit that does not involve the ignition switch. They can both be turned on when the key is out of the ignition. That is NOT true of the coil power which is only on when the key is in the run or start positions.
You said the hazards work fine until you turn on the headlights and then they (presumably the hazard lights) just glow dimly. That implies to me that your battery voltage is very low. However, you did not mention other problems to confirm this. Does the engine turn over quickly on the starter? How bright are the headlights?

Break this down into different areas. What is the real problem here? You have told us voltages but not whether or not the engine will start. Keep in mind that in cars with factory installed tachometers there are two (2) white/black wires that would have been on coil(-). One white/black went from the coil (-) terminal to the points in the dizzy. The second white/black wire goes from coil(-) to the tachometer. When aftermarket electronic ignitions are used, start by removing ALL white/black wires from coil(-). Connect the black wire from the ignition module directly to coil(-). Once the engine is running, determine which white/black wire is for the tach and connect it (and only it) to coil(-).




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