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Broke armature screw or loose screw.... By the way you are new here. I have built 1,000's of those pumps..... Glad you are into the oscilloscope program. We here at diesel place have been wanting someone to send us a screen shot of a good crank position sensor verses a defective aftermarket signal. Seems AC Delco has beaten the competition on these things and I wonder why.
 
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I threw over $3500.00 at mine with similar problem. Turned out it was the PCM. I was lucky to stumble across a shop that knows these trucks.
Ironically, after a year of running great it wouldn't stay running and is back at shop now.
 

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Discussion Starter #43 (Edited)
Alright folks, I have more knowledge, but maybe not anymore wisdom (yet)

(thanks in the interim for additional great comments--I guess I'm obsessing with figuring this out without pulling the lower intake manifold...)

I threw a klunky USB 2 channel scope on the PMD wires, and here's the report.

A good primer on what pins are what (found elsewhere here on this forum):

635475


So I'm looking at

B, which is the high powered fuel metering solenoid command signal (pulls the solenoid coil low, and the high side is apparently D, connected to Batt+ via keyswitch relay, as is the fuel shutoff solenoid)
B is also monitored by the PMD and provides some feedback to the ECU via A I believe, and also I think terminates the high powered B pulldown transistor (i.e. the ECU doesn't terminate B, it's terminated by some mechanics in the pump and a circuit in the PMD). If anyone can confirm this, that'd be great.

E, which is the pump-on command from the ECU, supposedly timed to crank angle.

A, which I think is the feedback for what B is doing to the ECU.

Note: when I turned the key on, and then cranked after the glowplugs, I would get these following traces, which fired the pump 3-4 times, no more and no less. Then nothing. Even after cranking a bit more. However, I could turn the key off and then do it again, so something is "saving state" at 3-4 firings and causing the ECU not to command any further fuel pulses.

Additionally, if I disconnected the optical sensor, which is supposed to put the thing into limp mode, I get NOTHING.

{WAIT--something wrong in my notes with the scope traces--getting new ones and will update}

So that leaves a few questions:

1) is the PMD doing the right thing? It appears to be, except for the delay.
2) what is the delay about? Now that I'm thinking about it, it could be the pump's stepper motor adjustable delay, though the ECU sets this.
3) what's happening after 3-4 firings? Why is the ECU (apparently) thinking things aren't right?

After all this I looked at the codes a few times, and it would throw a 13 and 62.
13: "Engine shutoff solenoid circuit fault"

hmmm.... I wonder if 13 is causing the 3 pulse shutdown.
 

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Discussion Starter #45
Okay.... got it squared away.

There are three signals the PMD is involved with.

A: "inject" signal from ECU to the PMD. The PMD takes this and energizes the fuel metering solendoid via B.

B: fuel metering solenoid on: PMD to Pump, pulls one side of the solenoid to gnd.

C: solenoid control: feedback to ECU from the "poppett valve" by way of the PMD. Apparently the fuel pressure and the fuel metering solenoid work to move this valve around and it's state is sensed (by way of B I think), and that is conditioned and send back to the ECU. In other words, this pulse is "on" when fuel is being injected.

The ECU according to other doc's I've recently seen, then turns of A to shut down the fuel metering solenoid. Previously I suspected the PMD could do this internally but this appears not to be the case.

Note: The ECU for some reason is only commanding 2-4 "inject" cycles before stopping. Key off-on resets it.

Here's some scope traces. These are from crank on to nothing.

Yellow is B (solenoid).
Blue is E, feedback
You can see there is some lag on the feedback turn-on, through the turnoff is pretty simultaneous. I suspect that the internal ECU controlled stepper-motor "advance" is the reason for that.

635482




This one is:
Yellow A: ECU's "inject" signal
Blue E: feedback

The lag in the fuel injection is again visible.

635481



Lastly, this one is
Yellow: A (ECU "Inject")
Blue: B (Solenoid)

There doesn't seem to be any delay there, and not surprisingly, B is A "amplified" (i.e. the fuel solenoid is activated as soon as the signal comes in from the ECU.

635483



So this all looks good as far as the PMD is concerned. Questions are:

1) Code 13--is the fuel shutoff solenoid bad, as has been suggested?

2) Is the fuel metering solenoid doing anything? Although there are only 3-4 inject cycles coming from the ECU, there seems to be some delay in the feedback and that's as I understand it, supposedly because the poppet valve is doing something. i.e. it suggest the pump is actually pumping, just 3-4 cycles at at time.

So what's causing the ECU to send ever shorter signals and ultimately stopping the fuel pulses?
 

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If you're getting DTC13, I know of no other way to verify the operation of the FSO solenoid than to swap it out or gut it. And even swapping isn't 100%, as there's no way to be positive that the new unit is opening correctly once installed. Unless you've tested it on another engine maybe. That's why I chose to gut mine. I wanted to be damn sure that there was no further possibility that it was the culprit. It's pretty easy to do. Just note that you will always find a DTC13 present if you are running a gutted solenoid. But once the underlying problem(s) are resolved, installing a new FSO unit is quick and easy.

I cant recall, but is there any IP inlet pressure sensing input signal to the ECM? If so, maybe a no-fuel condition might be why the fuel metering command would cease after a few pulses?
 

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Tip> The shut off solenoid can be gutted by taking a small snap ring out and removing the plunger.. The solenoid is basically a useless device that can kill your truck at any time. The IP will automatically shut the engine off when the key is turned off, without the solenoid.
Some will say it's needed but it really serves no purpose. Please don't confuse the shut off solenoid with the fuel solenoid. Shut off is the tall round cylinder thingamabob on the front top of the pump.
 

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Discussion Starter #48
If you're getting DTC13, I know of no other way to verify the operation of the FSO solenoid than to swap it out or gut it. And even swapping isn't 100%, as there's no way to be positive that the new unit is opening correctly once installed. Unless you've tested it on another engine maybe. That's why I chose to gut mine. I wanted to be damn sure that there was no further possibility that it was the culprit. It's pretty easy to do. Just note that you will always find a DTC13 present if you are running a gutted solenoid. But once the underlying problem(s) are resolved, installing a new FSO unit is quick and easy.
635512


This is the page I found on the the FSO in a GM Tech Manual which explains a lot but not quite everything...:

!
Also this one is good to have:

635513

Unfortunately this schematic doesn't distinguish between the various electrical components of the pump.

Anyway...

So the ESO (aka FSO/fuel shutoff solenoid) is supposed to be "hot in run" on one side (it is), and the PCM (been calling it the ECU, might as well get with the lingo...) pulls the other side to ground under normal conditions, energizing the coil. In my truck I pulled the ESO/FSO out (allen wrench plus some gentle persuasion from a channel lock), turned the key on, and when I plug it in, it persuasively retracts. The coil reads 17 ohms or so.

However, what I'm not understanding is what terminal E16 is in the PCM, that is supposed to read ignition voltage or it throws a code 13. If it's "BC16" in the first diag, or "C16" in the second, and if the PCM is pulling that to ground to energize the coil, what voltage is it supposed to be reading, unless there's an internal resistance to make a resistor divider in there somewhere. I see about 0.3V at the pulled down side of the coil at the coil, but who knows what's downstream.

I cant recall, but is there any IP inlet pressure sensing input signal to the ECM? If so, maybe a no-fuel condition might be why the fuel metering command would cease after a few pulses?
Here's what the first manual has for those subsystems:

635514
635515


It doesn't look like the fuel control is looking at inlet pressure, which I guess would be the "Boost Sensor". The boost sensor is only used by the PCM to control the wastegate. Nevertheless, I have it unplugged since I've got the top manifold off. I suppose I can try plugging it in and seeing if it gives more pulses.

If the crankshaft sensor was bad, that would throw a code (same manual). Same with the optical, though as noted before, if I unplug the optical, I get NO fuel pulses even though it's supposed to go into a limp mode (though now that I think about it, I read it's supposed to crank for 10-15 sec in that mode before it does anything, so maybe that's why I'm not seeing it.)


Sooo.... anyone have the PCM source code????!!!!
 

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There are manuals listed in the 6.5L FAQ page that you can download. You can browse to see if those might have the source info you need.
 

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Discussion Starter #50
There are manuals listed in the 6.5L FAQ page that you can download. You can browse to see if those might have the source info you need.
Hmmm.... not seeing a FAQ for manuals anywhere. Is that a premium thing maybe?
 

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Hmmm.... not seeing a FAQ for manuals anywhere. Is that a premium thing maybe?
It is available to all.
Located at the top of the 6.5L section are some stickys that are tagged in yellow(info) that contain the goto info or most sought after info for members:

Inside you can find manuals listed in .pdf format for most years
 

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DieselPro Gremlin Remover Do It.
 

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Discussion Starter #54
DieselPro Gremlin Remover Do It.
D'Pro, I don't doubt you for one second!!
But I'm obsessing with figuring this out without pulling everything apart. Might be throwing in the towel soon though...... LOL!
 

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Discussion Starter #55 (Edited)
Found this out of some manual:

Concerning the FSO:
CIRCUIT DESCRIPTION
When the ignition switch is in the "OFF" position, the engine shutoff solenoid is in the "No Fuel" position. By providing a ground path, the Powertrain Control Module (PCM) energizes the solenoid which then allows fuel to pass into the injection pump.

DTC 13 WILL SET WHEN
Ignition voltage on terminal "E16" when PCM is requesting engine shutoff solenoid "ON."

ACTION TAKEN (PCM will default to)
A current and history DTC 13 will be stored.

DTC 13 WILL CLEAR WHEN
The fault condition(s) no longer exist.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

Check for open circuit from ignition switch to the solenoid.
Check CKT 981 from solenoid to PCM for open.
DIAGNOSTIC AIDS
An open in CKT 981 or 339 will cause a DTC 13
Also a no start condition will exist. <-----
Hmmm.... might be on to something here.

So E16, which I believe is also the pin pulling the solenoid low, is showing voltage when it's not supposed to be, resulting in a "no start" condition.

I don't know how E16 can be high if it's energizing the solenoid, unless the solenoid is actually shorted to ground and the wire is broken somewhere, leaving E16 floating. It does however sound like E16 is both pulling down that pin and sensing it at the same time. It must have some sort of pull-up on it though.

I think what I'll do is with the FSO unplugged, short wire 984 (supposedly connected to E16) to ground to see if Code 13 goes away with the key on. Stay tuned.

More (from some other forum):

File In Section: 6E - Engine Fuel & Emission

Bulletin No: 87-63-04

Date: April, 1998

Subject:
Hard Start, No Start, DTC 13 or P0215, Service Engine Soon Light On (Replace Electronic Shutoff Solenoid on Vehicle)

Models:
1994-99 Chevrolet and GMC C, K, G Models
with 6.5L Diesel Engine (VINs F, P, S, Y - RPOs L65, L49, L56, L57)

Condition

Some owners may comment that their vehicle is difficult to start or will not start. In addition, the Service Engine Soon light may be illuminated.

Correction

If DTC 13 (1994-95 model years) or PO215 (1996-99 model years) diagnostics lead to injection pump replacement, a new on-vehicle replacement procedure is available for the ESO (Electronic Shutoff Solenoid. This procedure eliminates the need to replace the entire injection pump.

Parts Information

Description
Solenoid, Electronic Shut Off P/N 12561591
Does anyone have a copy of Bulletin No: 87-63-04?
 

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Found this out of some manual:



Hmmm.... might be on to something here.

So E16, which I believe is also the pin pulling the solenoid low, is showing voltage when it's not supposed to be, resulting in a "no start" condition.

I don't know how E16 can be high if it's energizing the solenoid, unless the solenoid is actually shorted to ground and the wire is broken somewhere, leaving E16 floating. It does however sound like E16 is both pulling down that pin and sensing it at the same time. It must have some sort of pull-up on it though.

I think what I'll do is with the FSO unplugged, short wire 984 (supposedly connected to E16) to ground to see if Code 13 goes away with the key on. Stay tuned.

More (from some other forum):



Does anyone have a copy of Bulletin No: 87-63-04?
What you posted is Bulletin 87-63-04 (y)
 

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I guess I can't help you here. Bypassing the shut off solenoid takes maybe 5 minutes. Diagnosing it through schematics, wiring diagrams, ECU functionality, electrical probability, shorts, crossed wires, and then asking the forum for suggestions takes up hours and hours of time. Not very efficient.
 

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Discussion Starter #58
I guess I can't help you here. Bypassing the shut off solenoid takes maybe 5 minutes. Diagnosing it through schematics, wiring diagrams, ECU functionality, electrical probability, shorts, crossed wires, and then asking the forum for suggestions takes up hours and hours of time. Not very efficient.
I agree it might not be efficient in some ways, but the fuel solenoid appears to be working. As I said, it retracted with authority when I took it out, hooked it to the connector, and turned the key on. When it's installed, there's nothing stopping that same retraction, and I can hear it happening too.

I could just start replacing everything, but that's not efficient either, in other ways.

But what is a problem is that it's throwing a code 13, and also that the PCM is only commanding 3-4 injection cycles on the fuel metering solenoid before giving up for some reason (which could be related to the code 13). Code 13 is that it thinks the FSO is not functioning because it should read low voltage at pin E16 and it's not.

I can imagine the PCM is shutting down the pump on account of an FSO error because it doesn't want the pump to run dry for very long if the FSO is indeed not letting fuel flow. Does this make sense?

E16 either it isn't low because of some bad connections (open or high resistance circuit most likely), or the PCM internally has a problem and isn't reading the voltage on E16 properly.

So I have two experiments in mind to determine this:

1) is to short E!6 at the FSO and see if it clears code 13. If it doesn't then I can pull out the PCM and check the voltage at the PCM. If that is low, then there is a PCM problem.

2) Get another solenoid (looks like $80-$100 will do it), hot wire the installed one, plug in the new one, and see if that clears code 13. If so, then I can install the new one. If not, return it I suppose.

However, I'm also getting the understanding that people are able to start even with code 13, so maybe there is a whole different issue causing the PCM to stop firing.

Anyway, I hope you see the method in my madness. In any case, thanks again for all your input.
 

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You did an amazing job the trouble is we don't have any reference point on those signal to compare it to.
In other words, we don't know how a good signal looks like.

Is the truck running at all?
Sometimes, code is just there.
If the truck runs, I will drive it around for at least a couple of days see if the code clears.
 

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Discussion Starter #60
You did an amazing job the trouble is we don't have any reference point on those signal to compare it to.
In other words, we don't know how a good signal looks like.

Is the truck running at all?
Sometimes, code is just there.
If the truck runs, I will drive it around for at least a couple of days see if the code clears.
Thanks, Trying....

Right now the truck will not start, period. However, I promise that once it does, for the greater good of all 6.5 mechanics, I will post scope traces!!

I'm waiting on replacement for some warranty/bad Bosche glow plugs (wth?! 3 of 8 tabs broke off to a light touch), so I'm not trying to fire it up today unless I put in some bad ones temporarily.

Should I clear the PMC with a hard/battery disconnect to get rid of the Code 13? Is there a better way?

I just got done testing the PMC connections to the FSO, and they are good. With key on and the FSO unplugged I get 0.030V at the pin (D16 in this case as it turns out), and 0.3V plugged in, both of which are what I measure at the FSO as well.

Interestingly, when I pulled the glove box there was a mouse nest on top of what appears to be some sort of relay bank on top of the vents. Wonder if it pee'd on something and it's causing a short of sorts.... or chewed a wire. Good grief.

I also case grounded the PMC to battery ground directly briefly, and that gives a 0.030V (30mv) difference in the measurements, but that's not too surprising. I wouldn't think that would be enough to upset anything. Anyway, no difference. Still getting code 13 (and 62 as well, BTW).

Next: I'm going to grab a spare FSO and try plugging it in, and also do a hard/battery reset.
 
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