Civic d16 no spark no injector pulse
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the negative on the coil should not in anyway have voltage/power.
no injector pulse means the ecu cannot see the distributor moving.
you need to figure out why the wiring is goofy.
no injector pulse means the ecu cannot see the distributor moving.
you need to figure out why the wiring is goofy.
Yes it can
think about it
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6,411 Posts
you are thinking the spark terminal.Yes it can
The NEGATIVE terminal should never see voltage.
It will if ground is not applied to the coil, but power from battery is still being applied to the coil from the positive terminal (which is normal), and everything is being powered and measured from a common source of potential.
If you take a meter and measure the negative side of the coil with the positive probe, using the battery as reference ground with the negative probe on battery negative, you'll see power at the negative coil terminal key on engine off, or during an ICM switching malfunction, because the coil is simply passing power through itself to the negative side, since its just a winding of wire.
The ICM is just a big NPN type transistor that switches ground to the coil when commanded by the ECU. Well, when the switch (transistor) is open, 12V (B+) is free to find its was through the coil power side, through the primary winding, and poke its head out at the coil negative. The power is not doing anything, its just chillin ready to meet up with ground when ICM turns on.
![sketch1609746413970.png]()
The same happens with injectors, since Honda and most OEMs like controlling devices via ground switching. Power is always supplied to the component at key on.
If you take a meter and measure the negative side of the coil with the positive probe, using the battery as reference ground with the negative probe on battery negative, you'll see power at the negative coil terminal key on engine off, or during an ICM switching malfunction, because the coil is simply passing power through itself to the negative side, since its just a winding of wire.
The ICM is just a big NPN type transistor that switches ground to the coil when commanded by the ECU. Well, when the switch (transistor) is open, 12V (B+) is free to find its was through the coil power side, through the primary winding, and poke its head out at the coil negative. The power is not doing anything, its just chillin ready to meet up with ground when ICM turns on.
The same happens with injectors, since Honda and most OEMs like controlling devices via ground switching. Power is always supplied to the component at key on.
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6,411 Posts
Strange. I guess it makes sense, now that I can look at the diagram.
Part of what I was thinking, was due to testing when I had the external coil on my old civic. Though I never tested the coil NEG with the key also on. Never felt the need to risk straighten my hair up, and general wary-ness.
Part of what I was thinking, was due to testing when I had the external coil on my old civic. Though I never tested the coil NEG with the key also on. Never felt the need to risk straighten my hair up, and general wary-ness.
Don't jump straight to changing the ICM. You also said your injectors have no pulse. What tools are you using to look at pulse from ECU to ICM?
Like Mattliston said, the ECM provides these pulses ONLY after receiving feedback from sensors in the distributor. You've got to look full circle before changing components, not just use the shotgun parts change approach. Don't be that guy who changes $1000+ in parts, only to have a shop find out that it was a broken wire or corroded terminal somewhere. Happens all the time.
The green wire in that diagram is supposed to carry a pulsed square wave from the ECU, but the transistor that provides the switching handles hardly any current. Do NOT use an incandescent test light to try and look at this pulse, you will kill the ICM driver inside the ECU quickly. An LED test light might also not be configured to pick up on the subtle changes being enough to turn on. My fucking stupid snap on LED test light is configured to work between 10 and 16 volts, you know how frustrating that is? In real world testing, its actually closer to 11 volts. You know how many cars after sitting can have 10.5 volt state of charge that still have plenty of juice to start an engine, or how many circuits use 0-5V stuff? Lmao thats why its dumb ass sits in the drawer.
Use a logic probe instead. 10 bucks at harbor freight:
These can convert very subtle digital pulsing into visuals. RED LED turning on means power/positive/higher than 0V, and GREEN LED means ground/negative/0V.
With one of these, you can even watch digital 2 wire hall effect sensors generate their square waves! (They generate VERY small change, but a square wave nonetheless).
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