Based upon the Electrical Schematic Diagram you posted... it makes sense that there would be NO VOLTAGE READOUT on the Voltage Gauge because the information involved is ordinarily provided by the Alternator Rectifier Circuit and then fed into the PCM for Signal and Duty Cycle processing FIRST and then it gets sent out on the
Dark Green Wire to the Splice Comb and picked up by the Class 2 Network
GRAY wire as PWM leading to the IPC 24 Pin Connector. No Alternator? No Voltage Reading! It's Pulse Width Modulation that changes the position of the Voltage Gauge Readings on the IPC under PCM Management... NOT the direct measurement of variations of Low Voltage Direct Current.
With all the design and build responsibilities that come with your having such a Creative Mind, sometimes it can lead The Inventor to have temporary 'Tunnel Vision' and to overlooking the need to
Back-Track and Re-Examine the IPC itself. Your images show that you have (2) IPCs available as your Test Subjects...
So... Try Pulling the IPC Back Covers off of them both and then
Examine and Re-Solder or Replace the MOBO Connections for the Voltmeter Stepper Motor(s). if either one or both Stepper Motors turn out to be Bad, you might be imagining problems with your New Design that do not exist within your Device. You could wind up Testing and Working on everything else before you take a closer look at the Absence of any Needle Swing on the Dashboard Voltmeter Gauge itself. I've had problems like this happen to me more times than I can count. I hope that THIS turns out to be the source of the issue.
One other thing is that since you are using the P-59 PCM-ECM (
BLUE-
GREEN) from one type of GM Vehicle and the BCM and IPCs come from other types of GM Vehicles, it would be helpful to know whether or not they are able to share Common Wiring Diagrams with your Test IPC Units. If not, this may be causing confusion as to which of the 24 Connector Wires are relevant to either one PCM and BCM .BIN configuration or another. If these items are all on the same page... please advise which particular Vehicle Make-Model-Series you finally decided upon and post that information back here:
This is going to sound a bit crazy... and a lot like some "Rube Goldberg" sort of Mechanically Clunky Idea... but in lieu of using the Electronic Signal Generator to Test the Tachometer and Speedometer... perhaps you could wire in an Actual VSS Sensor with a (2) Wire Harness Metro-pack Connector and then place or mount it next to a Small, Variable Speed Electric Motor (or a Dremel Tool) in close enough proximity to pick up the rotations of a wheel fitted with a small Gear, Fan or a Cylinder.
You will need to be able to accurately calculate what the Transitional Velocity of the Outer Edge of the Gear, Fan, Cylinder is turning at, based upon how large its Outside Diameter has to be to accommodate just the right number and spacing of the "Reluctor Ring Teeth" in order to make this idea work.
With teeth or grooves cut into it like a Reluctor Ring with Steel Metal Tape segments to trigger the Hall Effect, once this thing is Scaled to Convert 4,000 Pulses Per Second for each 1 Mile Per Hour to be shown on the IPC, then you could see how the PCM-BCM-IPC read-outs appear on the SPEEDO Gauge based upon variations in the Dremel Tool or Small Motor RPM. The attached image illustrates this Mechanically instigated Hall Effect "Square Wave Generation" Principle in action:
That same idea would apply for achieving "Real World Tachometer Conditions" using a wired-in Crankshaft Position Sensor (CKP) with a similar requirement of having a Small Electric Motor Driving a Reluctor Wheel adjacent the "CKP" Sensor after knowing how many times it needs to get Pulsed via the Hall Effect to accurately determine the RPM of "The Engine" based upon how fast that Dremel Tool or Small Electric Motor is turning the "CKP Reluctor Wheel" :>)
![1221902[1].jpg](/forums/data/attachments/148/148307-f47b7a4c6b0ce3ea02e9d5f62ee4bdf0.jpg)
