OK, after reading this, Part 1 -How to Test the 24X Crank Sensor (GM 3.1L, 3.4L) I have some answers, but more questions in some ways..

This shows the Yel/Blk as NEG, and would make sense as it is grounded and the Lt Green has power! Gah, WHY did GM feel the need to swap the wires!?!? And remember, my manual AND that diagram above both say the opposite..

Anyway, now that the 24x HAS POWER, and I did the ICM test that says its sending a signal to the coil pack, I'm left to wonder what the heck is causing this intermittent shut down?

I swapped coils when its acting up, and it's ALWAYS is in the same 5/2 spot!

So, now, I'm going to put it all back together and let it run for a bit and see if it shuts down 5/2 again.. once that happens, I will start the diagnosis again.

*headache*

 

Hello,
links bring a lot of information and many of us will thank you.

I have Yel / black to positive
and Lt green to negative.
all the time when ignition on

This must be a mistake in this documentation have reverse wires in the text.
But this documention for testing is so well made that we can not blame him

Did you test the 24X output wire as shown?

the 24X is can not be polarized and can work with food in any direction.

I had ignition problems with rough idle, there was DTC and finally it was a faulty coil (although it was like the others and seemed good to test).

friendly

 

What year is yours? The 24x test I linked is correct for mine, but the book and that chart is not.. so they may have changed at some point, just to confuse us and make us take it back to the dealer. feh

I tested the coil pulse with an LED and it worked, so I put the coil back, tried to start the engine, and it just turned over!! No fire!

I took the timing light and put it on #4, and turned it over again, and it flashed, but still wouldn't start. Checked fuel, it had pressure.. Tried the timing light again, and...

NOW NO SPARK ON ANY WIRE!!?!?!?!?! Cripes. Checked all the fuses and they are good. Checked power to the coil and its good.. I may try to return the ICU since it has lifetime warranty.

Going to sleep and try again in a few hours. Thanks for help

 

Back to sparking, but still not starting.. And I DIDN'T TOUCH A THING!! lol (not yelling, just emphasis)

Diagnosing it now...

 

Injectors aren't firing, BUT the 5/2 coil IS!?!

Checked all the fuses again, and swapped the ignition relay, just in case.. nada..

More diagnosing!....

 

I literally pulled and replaced EVERY fuse in the van, and all were fine. I also pulled the harnesses off the PCM and let it sit a couple hours, then replaced it too.

Now, it STARTS!!!

I shut it down right away as it was late, and I need to have the garage open, but I will investigate more in a few hours.

Bizarre!

 

Starts and runs, but still no spark on 5/2.

I checked the new ICU on the engine, and it didnt show a spark signal. So I swapped the OEM ICU with the wires, and it sparked! SO, I put it back on the old one and it didnt again.. result? NOT SO FAST! I put it back on the OEM and IT DIDNT SPARK!!

Back to the NEW one and it didnt spark for 4 rotations, then DID for 3 before stopping the starter... Didn't touch a thing, turned it over again, and NOTHING again!?

Eh, Going to take BOTH ICUs to the parts store to get checked, but I think its some wire or something.. But wouldn't a broken wire also cause the OTHER coils to not fire too?? Why are BOTH ICUs doing the SAME THING??

*HEADACHE*

Thanks all!

 

The PCM is connected to the ICM by four wires.
Bypass cntrl, IC cntrl, high ref, ref Low.
what are the functions of each wire?
it seems that the PCM controls the ICM but does not order it.
I remember I checked that there has ignition when the PCM is disconnected.

what you describe sounds like bad connections.
especially if it's always the 5/2
or CKP sensor (7x) has a defect; or is it dirty? it is not known exactly how the pulses are produced in time by the CKP. three pulses every two engine revolutions?

I had great difficulty in isolating a coil was bad, but then your failure is more straightforward, even if it is random.

I have two venture in 1998 and 2001 I tested 24x on 98 and confirm.
2004 is 100 miles from here.

the wirings are very different in these two models.

 

I replaced the 7x sensor and it does the same thing. I'm going to need a scanner with an oscilloscope it seems, to check the 7x now.

From what I gather the 7x (3x some call it) changes its magnetic field 3x per full crank rotation. I'd need a camera to see the marks on the crank, but maybe there is a piece of metal or something blocking one of the depressions used to pulse the 7x. I totally doubt this tho, so I have to stick to the electrics first.. for now at least.

You think if I replace a coil, and keep moving it around that might fix it?I checked for Ohms, and they were all the same, about 5.5k, so we decided aginst it. But since we already threw about $1100 at this thing so far (little by little) another $35 or so won't kill us.. (but any more and we may kill the van! lol)

Thanks

 

We must focus on 7x CKP.

you have changed the receiver; it is similar. but it may be that the issuer does not provide sufficient Magnetic Field? distance too great between. permanent magnet having lost its gauss?
Only the study of 7x wires YEL PPL signal can afford to see a difference in some of the pulses.

It would be very interesting to know the shape of the pulse train for how ICM can recognize the different cylinders to be supplied.

I recall that the "bad" coil was not identifiable with ohmmeter.