electronic ignition and coil check

[roy53]

How can you check if an electronic ign pack has failed and also if it is the coil that has failed.?

Roy

[RobH]

Presumably you have already checked that there is a good voltage supply to the coil Roy. 

You can check coil operation by disconnecting the the HT 'king' lead from the distributor and connecting it instead to a spare spark plug which is laying on some earthed metalwork like the engine block, so that the coil is powering only the one plug.   

Disconnect the short link wire that goes from the distributor to the coil terminal marked "- " ( or  "SW" if it is an older coil).  Connect a short piece of wire to that terminal instead. 

Turn on the ignition and touch the end of the wire to earth and then lift it off again (hold the wire by the insulation - there is enough voltage there to give you a small shock) .  Each time you disconnect the wire from earth you should see a healthy spark from the plug;  if so the coil is working. 

 

The way of testing the electronic ignition depends on what type it is and is best done with proper test equipment but you can get some idea using simple methods.

Assuming it is just a switching module that fits in the distributor in place of the points  - this test may not work well with more sophisticated ignition systems which have features like fixed dwell time. 

Disconnect the link wire from the distributor to the coil at the coil end.  Connect a small 12v bulb ( sidelight bulb is good)  between that wire and the coil supply terminal (which still has the wires attached) so that the bulb replaces the coil primary .  

Turn on the ignition - the lamp should light brightly and steadily.

Crank the engine - the lamp should dim a bit and flicker showing that the module is switching. 

If the lamp does not light at all, or lights but does not flicker on cranking, the ignition module may be faulty. 

 

 

 

 

Edited June 8, 2024 by RobH

[roy53]

Thanks Rob it seems the in distributor electronic pack has failed.

What confused me was that when it stopped working i pulled and prodded everything ,nothing.

Had power at both terminals of the coil but no spark .I then changed the coil to cap lead and it fired straight away. 5 mins back on road then dead .

Roy

[Waldi]

Hi Rob and Moderators,

your clear explanation on how to distinguish between a coil failure and distributor failure is worth bookmarking in the same way the ammeter-explanation is marked (staying on top of the list).

Keep them coming, please.

Thanks,
Waldi

[Ian Vincent]

2 hours ago, Waldi said:

Hi Rob and Moderators,

your clear explanation on how to distinguish between a coil failure and distributor failure is worth bookmarking in the same way the ammeter-explanation is marked (staying on top of the list).

Keep them coming, please.

Thanks,
Waldi

+ 1

[phil Dean]

I cut and paste them into my tech folder on my computer but also +2

 

Phil.

[TR Rob]

5 hours ago, phil Dean said:

I cut and paste them into my tech folder on my computer but also +2

 

Phil.

+3 I do the same !

[rcreweread]

I found some scissors but I couldn't find the glue stick so it will have to wait

Cheers Rich C-R

[tony Lawrence]

The only time I've broken down in a 6 was when I fitted electronic ignition and it failed...no spares so trailer home!

I now run with standard but quality points system with a spare set in the boot ...never needed them!

Live and learn!

[Lebro]

Electronic for me, & a spare in the glove box - much quicker to swap if necessary, but not needed to to in past 13 years.

Bob

[harlequin]

I have a 123 but carry the old Lucas distributor with points  tucked up under the fuel tank

George 

[PaulAnderson]

+1

[Chilliman]

6 hours ago, harlequin said:

I have a 123 but carry the old Lucas distributor with points  tucked up under the fuel tank

Same as me George, I run a 123 blue tooth in competition & also use it for touring, never had any issues at all, but I still have the fear of a failure in a system I can't repair & carry a stock unit built for me by the Dizzy Doc many years ago.