Could also be the timing cover that the sensor is located on is having “issues.” Come to think of it, it does have a slight oil leak at the bottom of the cover.. perhaps that is causing some issues.

Don't thnk so, the timing cover being loose wouldn't cause the sensor to move toward the reluctor. I would take that CPS and go to OReillys or a GM dealer and ask to see a replacement for the vehicle and compare the two. Rock Auto shows a AC Delco to be $51.

Assuming this didn't happen when the vehicle died (reluctor breaking) and it's been this way for some time, probably not the problem, but still too odd to ignore. It looks like a fresh grind, not one long oil soaked.


Charlie

This advice led me to examine the alternator this afternoon. What I found is a large single power cable for the battery connection. The smaller three wire connector had two wires cut off under the loom and the third runs to a warning light on the dash. That’s it, nothing I can see runs to the ECU from the alternator. The part that baffles me is where the voltage gauge in the dash is reading from. It shows an almost constant 14v when the truck is running.

Now I gotta go and try to figure out where the cut altinato wires are supposed to go..

You guys have given me a lot to check out and think about. Thanks!

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"I’m about as far as I can go with my limited knowledge and abilities."

Wow, you ought to get inside my brain for a few

Reading all of this and I think I have a problem (Right, TexasLefty ?)

I'm no mechanic but that CPS does not look right.

I may be confused on which generation ecu and wiring harness your using on which generation engine & alternator.
GM gas is not my area of expertise. I know enough to get by.
I / we do not do any dissimilar ecu/pcm re pinning to wiring harness or engine/body management or electrical componentry swaps other than addition of a/c, audio, gauges / minor gadgets.
Power train swaps or mating newer tech to older vehicle we only use correct ecu/pcm/bcm to correct/compatible wire harness to correct/compatible components eliminating any extras where they terminate, never up stream.

I also might have confused you with the alternator talk.
I said -
If you find the ecu is damaged at all, I would pay very close attention to the alternator connections & compatibility with the new ecu.
Connections and compatibility of the ecu/wiring harness and alternator if you find out the ecu was damaged.
Contrary to popular belief it is extremely rare for ecu's/pcm's to fry themselves, usually it is one or several input's that cause damage.

Going from an internally regulated 3 wire to an internally regulated 1 wire alternator isn't usually any problem.
There is debate which method is 'best', but dropping the exciter wire, field/jumper or both isn't going to create problems like you're experiencing.

I am not positive on this, seems with the ignition in the run position I'd think you'd have voltage going to the CS, if not try while cranking, if no voltage detected it aint never going run until the CS returns the trigger signal.

The PCM swap that was performed was fairly popular about 10 years ago before the plentiful availability of surplus LS drivetrains. They call it the “411” swap because 411 is the suffix of the part number of the newer PCM. Supposedly it gives the user much more tune-ability than the older PCM and you are able to squeeze all available hp from the vortec engine. Personally, I wish the previous owner had left the original PCM in there.

If the new PCM I have on order doesn’t solve this problem I may very well replace the entire harness with a stock harness and go back to the original PCM.

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What did you do about the Crank sensor? That being dead will cause loss of spark and what you showed is clearly abnormal.

Charlie

I installed a new sensor and put .060” of shims under it. .030” min clearance and another .030” to compensate for the contact. My plan, when/if if I get it restarted Is to keep a close eye on it and worry it if it continues. Probably not the best laid plan but all I’ve got right now.

I would stop buying parts, and buy a test light, then break out the wiring schematics. This buying parts and Hoping it fixes the problem is gonna get very expensive.

and rarely successful.

Seems the OP has used wiring diagrams & all the testing procedures & tools at his disposal and isn't using the parts swapping & hope method.

At least to me.






The question I still have is did you test voltage into & out of the CS?
Ignition in run position & while cranking.

If the CS is shot and or if shorts even if intermittent in the wiring or connector or anywhere along the path it aint gonna start, gotta have a signal to initiate bang.
The CS senses the magnetic field of reluctor wheel passing by thus sending a 'pulsed (if you will) signal' to the ecu.
No signal received - the ecu doesn't know the engine is turning / attempting to start. In turn it (ecu) doesn't trigger any of the other sequential in & outputs necessary to start / run.

Is the battery still fully charged at this point?

Yes and no.

I did check voltage to the sensor and voltage was present when keying the ignition. I did not have the foresight to check voltage leaving the sensor. I’d have to tap into the wire while it is plugged to the sensor. Because the sensor was destroyed and had to be replaced I never tested for an out going signal. I’ll do that this evening after work.

The battery is 100%

The short answer to all these questions and issues is to drop it off at a shop and pay someone else to deal with it. I may eventually be forced do that but my intentions (and budget) when I bought this thing was to do “everything” myself. I’m certainly no mechanic but I have learned and had fun tinkering with it. Ive actually done A LOT of work/improvements/mods to the truck and this is the first time I really feel like my back is against the wall. There are moments that I want to throw in the towel but I’m not quite there yet so thanks for hanging in there with me.


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