TRX300 no or weak spark

[B]Bad Voltage regulator can affect the ignition and cause a no spark condition.[/B]

Here 2 help said:

No - the rectifier/regulator only has to do with charging the battery. You can test the rec/reg by simply disconnecting it.

Click to expand...

My 2000 TRX450ES wouldn't spark, and the problem was the Regulator/ rectifier. I had trigger voltage coming to the CDI, 12v, ground, etc. but didn't have any voltage going to the coil primary.
I disconnected the regulator/rectifier, and it wouldn't spark.

Replaced the CDI, but that didn't fix it.
Replaced the Voltage regulator, and fixed my problem.
I even installed the Old CDI after replacing the regulator and it worked.

Bad Voltage regulator can affect the ignition and cause a no spark condition.

How can the Rectifier / Voltage Regulator affect Spark

The answer to your question is one the three leads from the Stator is wired in Parallel with the voltage regulator and the CDI (this is the link between the CDI and the Voltage regulator).

Apparently, at least one of the Diodes in my Regulator / Rectifier is bad affecting the AC current from the stator which feeds the CDI. This is how the Voltage regulator can affect the ignition system. (I did get some different readings between the 3 terminals on the voltage regulator that the stator leads connect to which would have led me to the bad regulator). The Honda Factory Service Manual does not indicate that the Voltage Regulator should be tested, nor do they provide any instruction on testing the Voltage Regulator on a non running engine (diode testing).

If you look at the wiring diagram and follow the stator leads, you'll notice the connection which goes to the CDI from this single stator lead between the stator and the Voltage Regulator.

There is a way to test the voltage regulator diodes (I've seen some posts about it), but I'm not certain that it is absolutely fool proof. And it is truly annoying when someone is asking for help with a no spark condition and guys post about testing the voltage regulator with the engine running... It's not running. That's why they are asking for help...

I never had a problem with the battery charging on this ATV, even when it started acting up. It would run sometimes, sometimes not. But the battery was always fine which would lead you to believe there is no reason to suspect the voltage regulator...

I just wanted to put this information out so that others that have this No Spark problem will hopefully see this which could speed their diagnosis and repair.

The dealerships have the advantage of being able to just plug in a new CDI and Voltage Regulator which only takes a few minutes to determine which is a problem as opposed to having to check every connection, ground, quick connector, and every device that can be tested with a multimeter before buying a replacement part.

If you have a no spark condition and everything tests good, and you've replaced the CDI, DON'T OVERLOOK THE VOLTAGE REGULATOR. IT CAN AFFECT YOUR IGNITION SYSTEM AND CAUSE A NO SPARK CONDITION.

Just Google testing your voltage regulator diodes Honda ATV TRX, and hopefully you'll find some instructions which can be done with a multimeter that has a diode test function.


https://www.google.com/search?clien...oltage+regulator+diode+test&ie=UTF-8&oe=UTF-8

Do you have a DVA Adapter?
Get one to test the stator before you replace it.

Do you have a wiring diagram for the ATV?
If not, get one. Manuals available inexpensively.
This will help you understand where each wire terminates and its function.


You can do a limited functionality check of the rectifier if your meter has a diode check function.

The only things that you can't definitively test with a multimeter and DVA are the CDI and the Rectifier. Everything else you can eliminate with a DVA and good multimeter.

Did you check the Pulse (pickup) coil?

You should test the wiring at the connector to the CDI unit for power from the start/stop switch, ground through the neutral switch, pulse coil output, ground, AC from the stator, and continuity to the ignition coil primary (from the CDI connector).

If these all test good, then reconnect the CDI and test for voltage output (using the DVA) from the CDI to the ignition coil primary wire.

If you have no voltage to the ignition coil primary, then your CDI and Voltage regulator are the only variables left.

You could do a diode check on the regulator, and if this checks out, replace the CDI first.

If you replace the CDI and still have no AC output from the CDI to the ignition coil primary, then replace the regulator. The voltage regulator can affect the ignition system because one of the legs from the stator is paralleled to the CDI.

By the way, if you have AC from the CDI to the ignition coil primary but have no spark, then the problem is with the ignition coil or spark plug.