Coil Relay

[movenon]

Like you I might be wrong. No expert for sure but this is how I see it.  Please forgive my explanation of the coil wiring.

Primary side (low voltage side):
Both coils are hot with 12-15 volts anytime the key switch is on via the 2 Red/White striped wires (one to each coil). There is no switching or signal on that leg of the coils, just voltage in the coils standing by waiting for a signal. That signal has to be ground to complete the circuit to charge/fire the secondary High voltage side (plug wires)  

Each coil has one signal wire going to the DCI.  One coil #1 Orange and coil #2 Grey.  These are the control (switch) wires.  Remember the other leg of the primary (low voltage) is hot with 12-15 volts anytime the ignition switch on.

The Secondary (high voltage) side:
Each coil has 2 legs (plug wires) on the secondary side.

Coil #1 has one wire to plug #1 and the other to plug #4  Both plugs fire at the same time.  One spark is obviously is wasted, not needed but that is OK. Wasted Spark system.

Coil #2 has one wire going to plug #2 and the other leg to plug #3.

That way the DCI's work load is cut.  Doesn't have to fire 1,2,3,4 in some sequence,  instead it fires 2 plugs at a time knowing that only one cylinder will be at TDC with fuel in it ready to light off.

I know you are already up to speed on this hooligan.  I was trying to add knowledge to others that might read this. And I hope it isn't misinformation.

Each coil is just a transformer with 4 wires (2 in and 2 out).
Example coil #1 input Red/white striped wire (ignition switched hot 12-15volts) and Orange wire going to the DCI.
                #1 output 2 wires (plug wires) going to cylinder 1 and 4

The Orange wire is the control. It has to see ground to complete the primary circuit. That timing is in the DCI which gets information from the pick up at the crank as to when to ground or turn on that coil.

Coil #2 has the same wiring except the control wire is Grey.

When we do the coil relay mod you disconnect (unplug) the Red/White (ignition switched hot wire) on both coils.  Replace that voltage to the coils via the new relay with a more direct route from the battery.  You use one of the Red/White wires you disconnected (doesn't matter which one) that did go to the coils and that is what will trigger the new relay coil with the other relay coil leg going to ground.

Boring as hell to read about wiring    The short is that the coil (transformers) have to be switched on and off. Either you switch the voltage input side or the ground side.  As the input to the coils are always hot with the ignition switch on it has to be a ground side switch and that circuit is in the DCI. ?  

IMO cleaning up the mounting points for the coil doesn't do anything as the coils are insulated from ground.  But cleaning the spade connectors hooking up the coils should be a periodical thing to clean.  They are up front and subject to some small degree to wet conditions. Don't point any magic wands or hose's up into the fairing area.  The Grey signal wire on coil #2 also feeds the tach I think.  If I had an erratic tach that is the first connections I would check.
George

[movenon]

All right George, back on the road again.
Good work.

How about you?  What I did was nothing compaired to you Mark.  I am taking a day or two here because of bad weather to do a few minor things that I put off as "someday" or "next time" or "when I get time" to do.  And there is a new tube of Semi-Chrome over there...........
George

[Mark Olson]

All right George, back on the road again.
Good work.

How about you?  What I did was nothing compaired to you Mark.  I am taking a day or two here because of bad weather to do a few minor things that I put off as "someday" or "next time" or "when I get time" to do.  And there is a new tube of Semi-Chrome over there...........
George

Well, engine is at rpm getting new trans gears,  shift kit , valve adjust ,and general once over. I had planned to do it myself but wound up with no time ..the rest of my list I am progressing well and my fj will be close to factory fresh..I still have a ton of polishing to do and still looking for a perfect lower cowling .

[FJmonkey]

Well, engine is at rpm getting new trans gears,  shift kit , valve adjust ,and general once over. I had planned to do it myself but wound up with no time ..the rest of my list I am progressing well and my fj will be close to factory fresh..I still have a ton of polishing to do and still looking for a perfect lower cowling .

Check your PM Mark...

[Mark Olson]

Well, engine is at rpm getting new trans gears,  shift kit , valve adjust ,and general once over. I had planned to do it myself but wound up with no time ..the rest of my list I am progressing well and my fj will be close to factory fresh..I still have a ton of polishing to do and still looking for a perfect lower cowling .

Check your PM Mark...

Got it, now check yours.

[Flynt]

IMO cleaning up the mounting points for the coil doesn't do anything as the coils are insulated from ground

Ill informed opinion maybe, but I think the type of coil we have (iron core) actually requires the core to be grounded or stray currents will develop and f'em up somehow.  This is mag amp knowledge from the old days, but I think it is important for the iron core coils or transformers to have a good ground for the core itself.  I'm not sure my jumpy tach was fixed by tis however...  I did clean the whole situation up as best I could at the time.

Frank

[movenon]

IMO cleaning up the mounting points for the coil doesn't do anything as the coils are insulated from ground

Ill informed opinion maybe, but I think the type of coil we have (iron core) actually requires the core to be grounded or stray currents will develop and f'em up somehow.  This is mag amp knowledge from the old days, but I think it is important for the iron core coils or transformers to have a good ground for the core itself.  I'm not sure my jumpy tach was fixed by tis however...  I did clean the whole situation up as best I could at the time.

Frank

No I think you have a point on the core Frank but I don't know how much it effects the performance. From memory the core's function is mainly for heat dissipation (current rating of the transformer and to deal with eddy currents).  But I am no electrical engineer.  Going back to heat dissipation, cleaning the mounting points would help with that. Heat and vibration is a known killer of ignition coils.

I mentioned in the previous post that the Grey wire is tied to the tach.. In the early FJ's it looks like the orange wire is linked to the tach and in the later models they used the Grey wire. I actually don't think it matters which one they both would read the same pulses. Just an assumption.

The spade connectors in the FJ were state of the art back in 1984 but they are not very good at keeping the elements out.  And they are relatively difficult sometimes to clean.  Anyone that has a tach acting up should do the same as you clean that area up first.
George