DT466e No crank scenario, ground problem

Hello all,

Looking for a little help on a no crank (and therefore no start) DT466e.

Truck was cranking and suddenly stopped. Lost dash lights, brake booster (it's hydraulic). I figured batteries let go, took them out and set them to charge. Tried them after a while, same outcome. Tried a different set (tested them off the truck as well), same outcome. Could not get the starter to turn over even when jumping it directly by jumping the solenoid. Figured bad starter. Swap a new starter in, no go. Same result. Ugh.

Watched a few videos on similar situations, read around the forums a bit, decided to try swapping out the solenoids under the fresh air intake (responsible for sending voltage to ECM), nothing. Same outcome.

Started checking grounds and wires for chaffing, shorts, etc. Couldn't find anything but I did notice the grounds on the starter have voltage (like 6.0V). Exciter cable on the alternator also has low voltage, as does the frame and dash. Pulled the exciter wire off, pulled alternator power cable. At that point all the disconnected grounds were ok so I plugged everything back in to the starter. Tried to crank with alternator off, nothing. Put the alternator wires back on, same outcome (positive voltage where it should be grounded).

What is going on with this thing? Is the alternator somehow back feeding current to what should be grounded? Appreciate any advice / ideas. Thanks!

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OK thanks, will look into that. I think I get what you are saying. Will try that in the morning. All day today and no cigar, super frustrating. Ugh

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OK updates on this:

The no-crank issue was resolved. Long story but there was a bunch of crap installed by previous owner (some sort of big brother tracker for drivers I would guess that was causing a problem). That clean up and some other stuff lead to finally a scenario where the new starter works and engine starts up again.

That said, now it starts fine, idles fine. Unfortunately it falls flat on it's face between 1700-2000rpm.

Have the following codes:
124 - Injection Control Pressure Signal Out of Range - Low
143 - Incorrect Number of CMP Signal Transitions Per Cam Revolutions
145 - CMP Signal Inactive While ICP Has Increased

Two things that are concerning to me: 1) fuel pressure is good (50+psi) but the needle is bouncing all the time and doesn't ever stabilize. Air in the line somehow? Tried diagnosing it but not finding a source or leak anywhere. 2) CMP pigtail shows neutral [wire 1 in pic], 5 volt [wire 2 in pic], and third wire which (I think) should show 12 volts only shows 4.9 volts [wire 3]. This is key on, engine off.

Appreciate thoughts/ideas. Thanks!

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Hey @Heavyd thanks. I'll come back and repost the VIN info, don't have it right now. Glad to see you're seeing this thread as I was just reading another on a similar situation where you were helping out.

For now I'll confirm it's a 1999 DT466e (with the 5 speed).

I did a lot of checking on this today.

Disconnected the fuel line, bypassed the filter, and ran it directly from a jug, results were the same (surging and power loss at around 2k RPM). Same engine codes.

I'm double checking all my connections and wiring but am not finding anything super obvious.

Voltage at IPR is pretty close to the battery voltage and I have the same numbers at the relay that goes to the ECM (atop the engine, under the fresh air intake for the cab).

Voltage at the CMP hovers around 5v (4.6v-5.1v). I had a friend check his and he had 12v there. I'm still thinking its a wiring issue but can't find what the problem is. All the other sensors on the engine also have around 5v.

A.