Apparent dead electronic ignition on G, Part 3

I have some news on a couple of previous posts stating that my G electronic ignition seems to have died. I sent the Petronix switch that I got from Denny's back to them with an explanatory note. A few days later , it showed back up at my place with a note that they'd tested it and it fired just fine. A few measurements from the tractor...12.56 volts to the resistor, 12.43 volts out of the resistor, 12.43 volts out of the coil, 1.8 ohms resistance across the resistor (which was difficult to get an accurate measurement on; the VOM also showed zero resistance on some measurements; the 1.8 ohms was the most repeatable non-zero resistance I saw. Denny's said that was likely accurate and that the resistor was a variable resistance unit), and essentially zero resistance across the coil. I am going to rebuild with a new distributor cap and coil to see if that makes a difference. The Denny's folks said they'd never had a coil fail, hence my reluctance to dend it along as well.

I will let you know what happens next; of course any suggestions or tips are highly appreciated.

Thanks,
Rob

Thanks for the wealth of knowledge provided on my problem. I will print out both posts and go through my tractor with a more critical eye.

The really odd part of this to me is the fact that the tractor ran fine (or seemed to, anyway) for 7 months prior to this happening. I'm trying to reconcile the issues raised in these and previous posts against that and wondering what has gone awry. I'm sure a loose wire or bad terminal is a possibility but isn't overly apparent based on the first cursory looksee.

The way it is wired is as follows: 12V out of the switch into the resistor and teed into one side of the switch. From the other side of the resistor, it connects into the + side of the coil. The other side of the switch is wired into the (-) side of the coil. There is no ground wire; should there be? They do not call one out. 2 wires out of the switch, period.

Again, thank you all; as soon as I can get a minute, I'll take the info and head for the barn.

Best Regards,
Rob

Quote: --"The way it is wired is as follows: 12V out of the switch into the resistor and teed into one side of the switch. From the other side of the resistor, it connects into the + side of the coil. The other side of the switch is wired into the (-) side of the coil. There is no ground wire; should there be? They do not call one out. 2 wires out of the switch, period.”

--That hall effect switch inside the distributor MUST take the ign coil’s non power feed side to ground when it triggers so the ign coil can produce a spark.. If it doesn’t have a ground wire (some units don’t) it must get its ground through the distributor’s breaker plate & then through the distributor’s housing to the engine case..

You really need to do that “test light (or voltmeter) on the distributor side of the coil while cranking test” then if you get a flashing light while cranking (or voltmeter reading swing) your distributor ground & hall effect switch is operating & grounding correctly & your problem lies in other places..

If your cranking test light test shows the test light on all the time, then try running an additional external ground to the distributor’s breaker plate as a test to see if it then flashes while cranking..

In short—IF, that hall effect switch in the distributor can’t take the coil’s non powered side to ground as the reluctor ring on the points cam passes the hall effect switch you have a switch problem, or power problem, or ground problem, or broken wire to the hall effect switch.. {as simple as that}………
..

Clooney

When I reinstall the switch and check the external wiring, I will do the VOM/test light on the distributor side of the coil test as you have suggested (among your other ideas) and post a separate set of results.

I have had somewhat similar situations to yours relative to company travel outside the country and have a vague idea what you faced when you returned. My thanks to you and all the others who have posted to help me out. Electronics is my Achilles heel, so everyone's patience w/me on this is highly appreciated.

Rob

Quote:--"A few measurements from the tractor"

…..Lets go through them, OK…..

**12.56 volts to the resistor, __That means you at least have a fully charged battery & have continuity to the coil (that’s good).. But it doesn’t tell us much more than that, or if you have excess resistance in the primary wiring.. By looking at your following voltage readings your hall effect (little switch in the dist) is “open” when you are taking the above readings so ALL readings are at NO LOAD so really doesn’t tell you much except they are all connected.

**12.43 volts out of the resistor,__ Again all that tells you is it’s connected as there is no load on it.. Ground the little DISTRIBUTOR SIDE POST of the coil with the ign switch turned on then re-measure that “resistor out” (should then show around 7-8 volts)

**12.43 volts out of the coil, __ Again doesn’t tell you much except the coil is hooked up & it’s primary can pass low current voltage.

**1.8 ohms resistance across the resistor (which was difficult to get an accurate measurement on);__ __That is about normal for a ballast resistor but can change slightly when a working load is placed on it & it heats up..

** The VOM also showed zero resistance on some measurements; the 1.8 ohms was the most repeatable non-zero resistance I saw. Denny's said that was likely accurate and that the resistor was a variable resistance unit).__ __Most ballast resistors are somewhat variable in resistance as they change resistance as they heat during use. Your resistor sounds good to go.

…OK, you need to more tests to really test you system...

1st , GROUND the distributor side post of the coil (ign switch turned on) then---re-measure the voltage’s

1)- Going into the resistor – should be over 12 volts {is it?}

2)- Going into the coil – should be over 6volts {is it?}

3)-going into that hall effect switch (the one you installed in the distributor) It needs 12 volts to work. {is it?}

_____ _THEN_____ _

Remove the coil’s distributor side ground wire (leave the one on going to the distributor) & hook a test light (or voltmeter) to that same distributor side coil post.. Then crank the engine with the ign switch turned on.. You NEED to see that test light flash off & on repeatedly as the engine is cranked over (or test light go from over 6 volts to under 1 volt).. If not, that hall effect switch in the distributor isn’t triggering on & off, or isn’t getting correct power or good ground (check the power & ground wire for a good CLEAN connection).
_____ _____ _____ _____ _____ _____ _____ _ OR, lets to cut to the chase__

Turn the ign switch ON,,,,, Hook a test light to the small coil post on the DISTRIBUTOR side,,,,, Then crank the engine over.. IF it flashes on & off, on & off, on & off as the engine is cranked over your internal distributor H/EF switch is wired correctly & operational..

If the test light is always on (probably is due to your voltage readings above) your little H/EF switch in the distributor isn’t working….

SO, check that it is getting a good ground (very important)

SO, Check that it is getting 12 volts of power (my guess is your problem lies here as it could be powered up from the coil side of the resistor & have low vlotage. (common mistake when wiring those things up).

You might want to print this out & take out to the tractor with you..

See what you do or don’t have based on the above then post back with any findings or questions..

Clooney

Regardless of points or elec ignition, you gotta have that voltage on the coils high input (NOT to distributor/switch) side when the Ignitions switched on (that means the switch is good and the ballast isnt open) ,,,,, ,,,,,continuity in the coils primary (between lil + and -),,,,, ,,,, and then:

When the points or elec switch is closed (which it usually is, only open when switch momentarily opens and coil fires at pistons TDC's), theres near ZERO VOLTS on the coils low to distributor/switch side. Then ONLY when the points or elec switch open, theres momentarily battery voltage on even the coils low to dist/switch side as no current (besides meter) is being drawn.

NOWWWWW WWW when you say you have near battery voltage OUT OF THE COIL, is the elec switch all wired up correct and the ignition on????? ???

CUZZZZZ ZZ if all is working and unless one of the pistons is at TDC and ready to fire (which they cant hardly come to rest there) the elec switch (or points) are normally closed and supposed to conduct coil current to near dead ground IN WHICH CASE THERE SHOULD BE NEAR ZERO VOLTS ON THE COILS LOW SIDE!!!!! !!!!! !!

If all is wired right n working and on THERE USUALLY SHOULD BE NO VOLTAGE ON THE COILS LOW SIDE or else the switch either isnt conducting current ORRRRR RRR its not getting it to ground.

1) Are you sure that BOTH wires to the switch (usually a black n white, one to voltage other to coils low side) are in place????

2) The switch has to get a ground return path, even if its good it grounds inside the distributor base etc., how is it attached inside???

If youre reading voltage on the coils low output (to swich/distributor) side, that tells me the coils primary is good and continuous and the switch n ballast n input side wiring are all good also. Sooooo ooooo that leads me to believe the problem is either

a) Switch is bad or not wired correct, or

b) Switch or wirign are NOT gettign a good ground, cuz if working, theres normally (except at TDC and ready to fire coil) ZERO, NOT BATTERY volts on the coils low side.

c) Is the hot feed wire to the switch wired ahead of the ballast and NOT on the low to coil side????? ???? I think they get full battery NOT reduced ballasted voltage.

d) Is the switch body or any extra ground wires well attached to distributor and is distributor well grounded???? CUZ IF THE COIL LOW SIDE NEVER SEES A DEAD GROUND (when switch is closed) THE COIL NEVER CONDUCTS CURRENT AND SHE WILL NEVER FIRE.

She acts like the switch isnt closed n conducting coil current either from mis wired or not connected to a good ground.

For the coil to fire, she has to have input voltage,,,,, ,,,conduct current to ground (via closed points or switch, dropping output voltage to ZERO NOT 12 AS YOU SAY),,,,, ,,and then momentarily open and interrupt that current flow (switch opens at TDC)

Let us know, Good Luck n God Bless

John T