94 Chev 6.5 turbo diesel starting problem

Ok, fuse did not blow. Lets go back to the beginning and trouble shoot it as an open instead of a short. According to the manual, the first thing you should do is Disconnect the Engine Shut-Off Solenoid with the ignition switch off. Now turn the ignition switch to the on position. Check for power on pin B 339 PNK wire at the solenoid. Do you have power? If yes, then here is what you do. Disconnect the PCM and check the wire continuity from Pin E16 of the PCM connector to pin A 981 Blu/Wht wire at the solenoid. If this wire is ok, and doesnt have an open, then you problem is either the new Solenoid, or the PCM itself. If you have an open, then find where the break is and fix it. Suspect the engine harness Pin A of the 15 pin Engine Harness connector.
Ok, lets say you dont have power on pin B of the solenoid with the ignition switch on. Go back to the fuse that you had to replace, and remove it. Check for power at that fuse with the ignitions switch on. If you dont have power to the fuse, suspect a bad ignition switch or a break in that line.
Now, if you did have power to the fuse, but no power to the pin B at the soleniod, you must find the break in that line.
According to the manual, this DTC 13 code is set when the Engine Shutoff Solenoid has a circuit fault. The next part I am going to type is a cut and paste from the manual. If you email me at Michael.D. Byers@Delta. Com I can send you diagrams.

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.

I dont know that I would waste my time swapping solenoids back. If you replaced the new one with another that worked, sounds like you got either a bad one from the company you ordered from, or maybe the wrong one. None the less, it is working, and I would be proud of yourself for fixing it.
:)