triggers

just what is a triggers function and how can you tell if it is bad?

Re: triggers

Triggers are low voltage coils under the flywheel that generate a few volts of electricity as the flywheel magnets pass by them. As the magnet poles change, the polarity of the electricity changes. The polarity change is sensed by the electronic ignition module and the higher voltage that was produced by the charge coils and stored in the electronic ignition module is sent to the appropriate ignition coil to fire the sparkplug.<br /><br />Trigger coils have continuity and measuring this continuity will indicate if the trigger is good or bad. If there is no continuity, the trigger is bad. Or more likely one of the wires that leads to the trigger is bad. If the continuity reading is out of a specified range, then the trigger is bad. This is done with the motor at rest.<br /><br />You can also test for voltage coming from a trigger as the motor is running. But this is kind of a catch-22. If the motor is running, the trigger must be working. Unless the motor has more than two cylinders in which case there will be multiple triggers of which you can test each. One may be working and the motor runs badly, but another might be bad and there'll be no spark to that cylinder. You can also test for voltage by cranking the motor with the starter. Hard on the battery, plus you need two hands to hold the tester leads and another 10' arm to reach the key switch. Obviously you can get around this with alligator clips and/or an assistant at the key switch, but continuity checks are much easier and just as reliable.<br /><br />That being said, triggers are about the most reliable component in an electronic ignition system. Since the trigger is physically moved to advance and retard the timing (on most motors), internal breakage of the wires leading to the trigger coil is the leading cause of trigger failures.<br /><br />Continuity checks are done with common multimeters. Trigger voltage might be testable on some systems with a common multimeter, but many need something called a DVA adapter which isn't real easy to find.

Re: triggers

WillyB -- Great stuff! Is there a way I can do some basic tests on coils in a magneto system? I would like to be able to do a continuity test to see if one or both coils are bad, or maybe a simple resistance test with my meter. (emphasis is on simple, because I don't understand the electronics -- but can probably run a test if told how to use the multi-testor to do so, even if I don't fully understand what the results mean.)<br /><br />So can I bench test the coils?

Re: triggers

You can bench test ignition coils, charge coils, and trigger coils with a common multimeter. You can't bench test an electronic ignition module. Generally, if all of the other components test good, it can be assumed that the electronic ignition module is bad. All of the wires need to be isolated from the system in order to get correct resistance readings...in other words, the component you want to test has to be disconnected.<br /><br />Service manuals will have acceptable ranges that the readings have to fall within. Sometimes you can find them at public libraries. If you intend to do your own work on your motor, buying one would be a better idea. There are factory manuals which you probably can't get, but there are a variety of aftermarket manuals available. I like the Chrysler/Force manuals because they take you step by step in easy to understand language, and they deal with commonly available tools and meters.<br /><br />The same is true with magnetos, but condensers aren't testable with common multimeters, unless they're shorted out. You probably have two of everything for a magneto on a twin cylinder. You can sometimes compare readings from like components to determine if one is bad and one is good. Problem is, which one is bad and which one is good? I have also known of flywheels where the magnetism weakens over time. I don't know of any way of testing them, or remagnetizing them. But if everything else tests good, I would suppose that the flywheel is weak.

Re: triggers

Thanks for the come-back. As a matter of fact, the coils in question are on a Chrysler 9.9 Autoelectric -- have the service manual as well as the insert for the autoelectric. I haven't seen specs for the coils, but I'll check again. One of the things I could probably do is compare the two, although I won't know which one is good or bad if there is a variation. The coils look fine, but I haven't been able to get spark yet. (Problem might indeed be the flywheel magnet.)