2006 Bonneville 790, No Spark, Ignition Control Unit Defective?

Well you are right, outside of an electronic lab the igniter can really only be tested by substitution. However, the more likely culprit is the pick up coil which is also much cheaper. You should get about 570 ohms resistance measured at the connector tucked up to the RH side of the battery under the side cover.
Have you also checked to see if you are getting battery voltage to the +ve side of the coil? No power would point to the igniter if is itself getting power. Equally it could an internal failure that is not cutting coil power and hence not collapsing the magnetic field to induce the spark.
Your cheapest igniter replacement is
https://www.triumphtwinpower.com/fire-starter-performance-igniter-unit.php

 

Ouch! Sounds like the igniter. The problem with coils is that they can appear to be ok but break down under load or heat - it is just a break in a very fine wire winding. They do not always show an open circuit in the winding.

Failing a local test igniter swap.....Get cheeky. If you send your igniter to TTP (above) for a £112 remap - telling them you think it dodgy - they can test it for you and, if defective, supply a new £234 unit......

Either way, you will get a worthwhile modest performance benefit - especially starting.

 

The coil has two entirely separate circuits. They are NOT connected so low tension to high tension will show an open circuit.

Set multimeter range correctly!
The 12v tabs with spade connectors should measure about .7 ohm tab to tab.
And the High Tension circuit (spark lead socket to socket) should read about 18 kiloohms.

 

A small afterthought.

Having previously proved you have 12v at the coil you have shown continuity in your wiring loom - part of the reason I asked you to check. The igniter is triggered by a pulse from the pickup coil to cut power to the ignition coil. The spark induced fires in both cylinders - one approaching top dead centre on compression, the other on exhaust (so called lost spark).

The igniter reads engine speed from the signal and applies the appropriate advance from the throttle position sensor. As the igniter MUST be getting power if it is present at the coil then, by a process of elimination, you can be pretty confident that a failure to spark is caused by internal igniter failure. There is pretty much no other explanation as all the safety switch circuits inhibit the starter circuit but not the ignition circuit which is energised by the key.

 

Nailing down an intermittent electrical problem is the trickiest of tasks. Even when you are totally systematic it can fail to manifest itself when you check.

Without placing any probability on where it lies, it could be:

a dodgy connection in the harness - two multiplugs. One in headlamp shell, one under fuel tank buried in tape. If the bike turns over without sparking discount these bits of the harness - they must be ok.

The pick up coil. It could pass impedance/resistance tests but still fail intermittently to generate a pulse. Result - no spark. Part no 1 https://www.worldoftriumph.com/part...g/triumphmc/modelid/3130/block/100064758-0-2/

The new ignition coil. Possible but unlikely. Is it Gill (OEM) or PVL? I have more faith in PVL!

The igniter. Check it for marks and the underside of the seat. There is a known issue of pressure from the underside of the seat crushing the casing and knocking out the sparks.

At the end of the day you are faced with replacing suspect parts until the problem disappears. Your guess is as good as mine between pick up (common) and igniter (less common) and you know exactly how and when the problem manifests and if is purely an ignition problem. When it runs out of sparks check that live feed to the ignition coil! Instinct says igniter or pick up coil. Pick up coil exhaustively tested in pan of hot water to replicate engine heat. Gap installed .8mm

 

One thing i would add is double check the charging circuit before spending out for a new igniter...it could be showing a relatively heathy 12.8v but when running and there is more current draw if there is a problem with the alternator or regulator/rectifier the voltage available may not be enough to give consistent results, so to be on the safe side i would first check.

 

If the engine cranks it should certainly spark.

Without spectating it can be difficult to know how much someone knows about testing the ignition circuit. You would need something like an oscilloscope to measure the pick up coil output - an ordinary multimeter would probably not register the pulse.

It seems almost certain the problem is with the pick up or the igniter. The difficulty is knowing which. The pick up is cheaper........ but you might actually need the igniter.

Tentative en Anglais veux dire ‘provisoire’ ou ‘timide’. Le mot juste est ‘attempt’ !

 

From a complete electrical numpty, check your earth lead connection to the frame. Just saying.

 

Correction!

Rectification is redressement de courant!

And I have forgotten most of my French.......

 

To check the ignition coil totally disconnect the wires from the ignitor to the coil.

Fit a spare spark plug into the HT lead and make sure the body is earthed

Connect one side of the coil to the battery positive with a new wire.

Connect a new wire to the other terminal and touch it to earth ( frame ) on and off

This should produce a spark at the plug, if no spark the ignition coil is faulty.

 

Really pleased for you. Felicitations!