4-pin HEI module pinout?

Holding module with convex side down or toward you, upper left is terminal "B," battery; lower left is "C," trigger; two on right are for pickup coil.

Thanks. So, pickup coil wires go to two RH terminals, "B" gets +12V from ignition switch, and "C" goes to coil (-) primary, yes?

Thanks DS

affirmative

This pictures shows the internal HEI shematic and wire circuit but not the IC circuit. The RH you referred to on the left side could require a correct polarity. If inputing external power source as to trigger, it normally requires a correct polarity.

Koji

Great info on that page, but one last point of confusion: We see the upper-left terminal marked + connected to the coil primary +, and the lower-left terminal connected to the coil primary -. This must mean the module is fed +12V in parallel with the primary + of the coil, yes? That is, an ignition switched source of +12V must simultaneously feed the upper-left module terminal and the coil primary +, yes?

DS

CORRECTION; the RH is on the `RIGHT` side.

This picture shows the internal HEI schematic and wire circuits but not the IC circuits. The RH you referred to on the ``RIGHT`` side could require a correct polarity. If inputting external power source as to trigger, it normally requires a correct polarity.

Koji

This site shows pinouts for GM/Ford/Chrysler ignition boxes, plus how to make them work on just about anything.

Koji San wrote:

I'm not certain what is meant by the right hand on the left side, but yes--on some HEIs, the pickup coil leads are crossed while others are not; it is advisable to retain this configuration when switching modules. Crossed or not was indicated by color of the connector; crossed pairs usually have a white or black connector, non-crossed yellow. Some sources indicate that a crossed wire pickup requires the primary winding leads to cross as well. Failure to retain proper orientation here can lead to intermittent "no start" or "no power" problems. However, the pickup coil (timer core in GM speak) produces an analog (AC) signal, so polarity isn't necessarily an issue, particularly since the original poster suggested that he was using the HEI module to rig a non-GM car. The zero voltage threshold (switchover from "positive" to "negative" portion of wave as viewed on an oscilloscope) of the pickup's signal is interpreted by the module (effectively a Darlington pair) as in instruction to open the primary winding circuit (as connected to module terminal C.) All electronic ignition modules require a power source, thus the B terminal should receive 12v from an ignition-switched source. The remaining terminal is the aforementioned trigger, terminal C. This connects to the coil negative side, as virtually all ignitions are ground-side controlled, and leads into what amounts to a relay inside the module, which is used to interrupt primary current. We are *not* inputing an external power source here, that would lead to bad juju, like car no vroom vroom. The ignition fires the plug by interrupting primary current flow, thus collapsing the magnetic field inside the coil assembly and inducing voltage in the secondary. Grounding of an HEI module is provided through the case of the component, where one of the mounting screws shoulders against a metal ring embedded in the plastic.

Correction, the RH (right hand) he referred to on the right side. (This is grammatically redundant, please ignore.)

Correct, the reluctor produces an AC sawhorse waveform. I`d noted just in case some reluctors have embedded polarized capacitors, which is unlikely. Or an external trigger is used in case of non-GM applications or modified for computerized control, which is unlikely.

There`s no relay. Koji

Yes.

Yes. Good question.

Note that the post read "...*what amounts* to a relay inside the module.." (emphasis added). I concede that an actual relay is not contained in the module, but as the circuit in question is switched by an output associated with the module's dwell predictor circuit, the function can be likened to that of a relay, which is all I intended to express. I stand by my words.