I thought I’d close out the thread I started. First I’d like to thank Chuck for the advice and diagrams. It appears that you have helped a lot of folks here. My problem after performing the initial electrical diagnostics is that I found it particularly difficult to positively check my transistor module. I quick review of prior posts never found anyone who performed the test and posted their results. While the actual numbers aren’t that important, I could get no readings with a digital voltmeter bit would get diode resistance from an old analog meter. So, I ended up basically doing a reverse check on all the leads to the module which pinpointed the fault. I think this should help on any 322 problem when you do not have a spark on one or more cylinders and can verify that you are getting voltage to the pink wire at the coils. I’ve only diagnosed this one electrical problem on this tractor, so I’m not an expert by any means. I’m posting this just to give my results back, and to those so inclined as just ideas and what worked for me.
My JD 322 died while idling and I had no spark, but had voltage at the pink lead to the coils. I performed the initial diagnostics, but could not verify I had a defective module from the chart found in at least in the TM-1277 manual. I also did not have access to try and swap out with another module. Before I spent about $300 on a new one, I wanted to double check all the circuits that the module accesses. If these checked out then I felt reasonably assured I was on the right track. Here’s a summary of what I checked.
1) Leads at the X27 connector. With the Key on and all safety switches closed (seat, neutral etc.) there is 12V between the Pink/Black and Pink Leads. (Module gets power and is grounded)
2) Leads at the X27 connector. I removed the plugs and grounded them. Again with the key on, and quickly grounding the white/Blue, Black/Yellow, and White Leads one at a time, there is a spark at the number 1, 2 and 3 plugs. (Leads to the coil and coil are OK)
3) Leads at the X24 connector. The resistance between the Black wire to the Green, Brown, and White Leads are in the 19.2 – 19.5 ohm range. (Leads to the pulsars are OK and most likely the Pulsars are OK themselves)
These tests all checked out and by themselves are probably sufficient to justify that my transistor module was bad, but I also did a couple more things. I checked that the power across the leads in 1 above was sufficient to light a 12V bulb. This was to insure that I did not have a high impedance connection in those lines. In other words a connection downstream that could give me 12 Volts but not enough to carry any usable current. I actually found this once working on a 1972 Camaro. My last double check was for the Leads at the X24 connector, Here again the above test #3 is most likely sufficient but I also found that with my voltmeter on the AC setting, I could detect a small blip on each of those three pulsars while cranking the engine, indicating that at least some signal was getting to the transistor from the pulsars.
I ended up purchasing the model and the tractor started right up. So the other piece of information is that this module can fail and knock out all cylinders. So not only is it possible it happened.