2005 PLSOR cuts after starting

[Harkonnen]

if so why not add a direct B+ supply to the suspect part as a test or monitor it with a test lamp or vom to see whatahappens when you release the starter cct.

That's roughly my next step once oscilloscope arrives. I bet I'll see a voltage dip on R/Pu when starter disengages and work from there.

 

[saltchuckmatt]

One plug, one jumper wire....so easy.

 

[Harkonnen]

Nope. Not on the powerpack, not on the diagram. Y/R starts at ignition switch, runs to shift interlock and then aft to solenoid. Nothing else is connected to it as far as I can see.

Oops, I guess there IS a weird Y/R branch to powerpack. I stand corrected.
So if it supplies juice to the pack while cranking, and then coils take over, except that they don't, and coils are nominal, what is my problem, then?

Safe enough to disconnect Y/R at the pack and see if it runs with straight 12v to the pin, what do y'all think? I don't trust those semiconductors.

Progress. I give Y/R pin at powerpack 12V and engine runs until I disconnect it. Must be a problem with handing over to coils.

 

[Crosbyman]

is this a new to you engine... anybody worked on it YR is typical START .

any chance "a purple" should go to the power pack ? ...sorrry I don't have a diagram but it seems that woud solve the problem

 

[Harkonnen]

is this a new to you engine... anybody worked on it YR is typical START .

any chance "a purple" should go to the power pack ? ...sorrry I don't have a diagram but it seems that woud solve the problem

Y/R is Start, but there is also a branch to powerpack that I overlooked.
Pu runs from ignition switch to reg/rec, and then to OMS, and branches off to dash before that. Since I lose dash when I release starter, I can only conclude that Pu voltage collapses then; will have to check tomorrow. I would blame reg/rec, but that should not affect ignition, I imagine, because it is powered by its own set of stator coils. Eeeenteresting.

 

[Harkonnen]

Quick update. Low-voltage side appears innocent. Narrowed it down to either stator or powerpack. I'll have local shop test output on both, because I do not have the equipment to load-test that stuff.

 

[Harkonnen]

Case summary.

Symptom: 2005 Johnson J115PLSOR fires up, but dies as soon as the starter key is released.

Additional observation: Engine continues running when +12V is supplied to the Y/R connector at the power pack.

Stator testing: Results were inconclusive—probably due to a less-than-ideal meter—but no shorts to ground were found.

Hypotheses:

Faulty power pack
Faulty stator

Test: Replaced the power pack.

Result: Engine now operates normally. System voltage is approximately 13V at idle and 14+ volts at 2000 RPM. Based on the charging voltage, the stator appears to be functioning properly.

Conclusion: Faulty power pack. The stator is probably innocent. A rare occurrence, since replacing expensive parts usually only confirms that the other expensive part was the problem.