Igniton system question

spark. Voltage to the

Is this normal or

changing voltage that

secondary winding.

but only reads .2

fluctuating when the

fluctuating rather

The voltage to the +ive side of the coil should be a steady 12V (or

8-9V in the case of a points ignition system) WRT ground when the engine is running, so it sounds like that's not your problem. The

-ive side is the one that is "switched" through the points (or electronics) when the distributor is spinning.

nate

Voltage to the

Is this normal or

changing voltage that

secondary winding.

but only reads .2

fluctuating when the

fluctuating rather

More likely, you blew your meter when you connected it to the primary. There are 10kv inductive spikes and few meters will survive it.

A coil can check out 100% and still be defective.

Thanks, Nate.

If the -ive side is switched, then the voltage, as read across +ive and -ive wires should fluctuate, right? That is how I measured it. This Pathfinder has a two wire plug that plugs into the +ive and -ive terminals of the primary winding. I unplugged this connection and measure across the wires feeding into the plug, through the -ive wire coming from the ignition module, not directly to ground.

The voltage measured in this manner should fluctuate when the engine is cranked, shouldn't it? If this is so, then I need to look at the igniton module, the interrupter mechanism in the distributor, and the engine computer.

I worked on a differnet friends 96 Kia Sephia that had a no spark situation which, as it turned out, was caused by a sudden short circuit that fried the engine computer and fused a bunch of wires in the main harness.

Jack

Nate Nagel wrote:

I disconnected the two-wire plug going to the primary winding and measured the voltage across these two wires while cranking. That is the measurement that I suspect should be fluctuating. Since it was not connected to the coil, the meter was not fried.

Even if the coil was fully connected and I measured voltage across these terminals while cranking, the meter would not have been connected to the secondary winding and should be safe, no?

Jack

TCS wrote:

fluctuating when the

fluctuating rather

No 10KV on the primary, 200-300 volts -if- everything is working okay. KV is on the secondary which he didn't connect to.

Nope. Thing is, few have the means to test it 100%.

Don't sweat it. There is no 10KV on an ignition coil primary.

voltage across

be fluctuating.

The ignition module won't work without a load.

It isn't a "push-pull" device where it has an output that connects to ground and then connects to 12V. It is just a switch that is either open or closed. Unless you put a load on it to pull up the output to 12V, you'll never see any signal.

Thanks, Neil

I wasn't worried. I had the the + and - wires going to the primary winding disconnected when I tested the voltage across them while cranking the engine.

I was looking for fluctuating voltage across these wires as the engine cranked over, but all I got was a steady DC reading of about 10 volts. I figured this was telling me that the trigger device that sends a signal to the switching transistor, or the switching transistor itself might be faulty. It is raining like hell here right now and my friend's Pathfinder is parked on the street or I would be digging into it now.

I figure the next step is to test for a signal coming from the trigger device in the distributor and if that checks out, then test the switching transistor.

Am I on the right track here?

Jack

Neil Nels> Don't sweat it. There is no 10KV on an ignition coil primary.

I disconnected the +ive and -ive wires going to the primary winding of the coil and tested across these two wires while the engine was cranked. I was expecting to see a fluctuating voltage, but instead, I got a steady DC reading of between 10 and 12 volts reading across these two wires. In other words, I disconnected the coil from these two wires and inserted the leads of the meter in its place.

Jack

TCS wrote:

wires should

plug that plugs into

connection and measure

ignition module,

cranked, shouldn't it?

mechanism in the

Jack, You have the right idea, but the wrong method of testing. The coil should indeed switch, but you need to measure from the (-) side of the coil to ground. Key on, engine off you should see system (battery) voltage. Engien cranking, voltage should fall and indeed pulse. You should also know that most voltmeters show an AVERAGE voltage. If you are using a cheaper meter, it may not show the fluctuation. A better test is to use a heavy duty 12 volt test light. Connect it from coil (-) to ground. When cranking, the light should go dim (battery volts fall durning cranking) and then the filamint should obviously pulse. If you use a regular test light, the collapsing field of the coil can take out the bulb(voltage will spike over 50 volts on coil primary as field collapses)

spark. Voltage to the

cranking. Is this normal or

changing voltage that

the secondary winding.

I just went through this with my brother's Mazda 323. It died between shifts and had no spark. We were lucky enough to be able to swap in another coil and return it to the store after it didn't fix the problem. It didn't seem like the problem anyway since the resistance of both windings were within spec. A quick check of the ECU codes showed that it was not getting the Ne (I think) signal indicating when to spark. We replaced the sensor in the distributor (by way of a new, used distributor), and it turned right over.

One thing someone suggested as we were troubleshooting, is that you can swap in any old coil as a test, and I guess that's true, I never thought of that but it makes sense and his coil and connector looked identical to the one in my Altima.

Anyway, I hope this helps, you didn't mention if you'd checked for any codes in the ECU, that might give you the clue you need.

It turned out to be a broken timing belt. When the rain here let up, I popped the dist. cap and watched as the rotor just sat there while the engine was cranked.

Thanks to all who replied, Jack

JM wrote: