CDI diagnosis help NTV600 no spark

[Amreet]

Hi guys

my NTV failed to start after work yesterday. Ripped it apart and went over it with a multimeter, the loom side of both coils has good voltage with the ignition on, but there is no spark. Does this suggest that the CDI box is at fault?

On NTVs the system has 2 pulse generators, leading to a single CDI box, which feeds 2 coils which feed 4 plugs.

There is no spark on any plugs, so both coils wouldn't have failed out of the blue (theyre very robust anyways) at the same time, and im assuming that both pulse generators wouldn't have failed (but will check resistance later today) so this leads me to thinking its the CDI box failing to rear or deliver a pulse signal. Also a short in the loom would presumably only effect one coil or one pulse generator circuit. Am I right or wrong?

Any advice much appreciated!

Thanks

[jjdugen]

Not overly familiar with these. Usual checks, sidestand, clutch switches. I do know that Honda fitted a sense diode in many ignition switches on bikes of this era. It sends a 9v supply to the ECU, if this goes short it gives the symptoms you describe. Can't find a decent wiring diagram yet, I'll keep looking.
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[Amreet]

The clutch/neutral/sidestand kill switch all stops the start motor and ignition so if one of those were at fault the engine wouldnt turn whereas the handlebar kill switch allows you to turn the motor over but with no spark

Just measured the two crank position indicator coils and one is in spec at 450 ohms the other is way out at 800ohms. Does anyone know if these two work in unison for both cylinders or is one front and one rear? Does this explain the lack of spark from both coils?

[Amreet]

more updates, pulled the CDI out of its case, and had a scout around the components, there are two diodes seemingly in parrallel, both offering equal resistance in both direction so im assuming that theyre shot? might try soldering in some new ones. they look a bit dodgy under the microscope but im not totally sure tbh hard to tell under the potting compound

[WD Forte]

Not an NTV expert, but a quick peruse of the wiring diagram
suggests its a TCI not CDI ignition system to me.
TCI is basically a bunch of transistors while CDI is basically SCRs and dump caps.

Might be worth bearing this in mind while you dig around in its guts
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[cb1rocket]

I have had several Hondas and if everything else checks out then it's usually the pick up the coil. The cdi or the ecu rarely fails.
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