[Paul Workman]

Ah! youz guyz are over thinking this, methinks! (Refer to the 90-92 and the 93-95 diagrams)

And, because there is a common misunderstanding of different terms going on here (i.e., voltage vs. current [amperes]) and what the two entirely different terms/quantities refer to...descriptions get unnecessarily messy here.

Soze we don't get confused, VOLTAGE is analogous to water PRESSURE in a plumbing example. Voltage does not "flow". It is what it is at any point in the circuit.

CURRENT, electron FLOW measureD in "amperes" is analogous to water flow in our plumbing example. Current flows as result of differences in pressure (voltage); flows from high pressure to lower pressure in the circuit.

90-92 starter circuit:

Battery CURRENT flows through the start switch and then to the VATS relay (controlled by the CCM) and then to the CLUTCH START SWITCH before powering the solenoid actuator coils, and then returns to the battery (via chassis ground), completing the round trip circuit.
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93-95 starter circuit:

Battery CURRENT flows through the start switch and branches through the VATS relay and through the CLUTCH START SWITCH to VATS actuator coil and then returns to ground through the CCM module.

CURRENT through the VATS (high current capacity) relay path goes directly to the starter solenoid.

AT ISSUE in 90-92 cars...

At issue is the relatively high current drawn by the starter solenoid itself and the limited inability of the CLUTCH START SWITCH to handle the relatively high (~10 amps) of the starter solenoid actuator coil windings, long term.

The voltages (seen on the 90-92 diagram) are from a presentation by Marc Haibeck. They (voltages instead of current readings) provide valuable troubleshooting information, being much easier to measure than a current measurement, far as tracing an open circuit goes. If you have voltage or you don't have voltage when the ignition switch is in START, you have a clue as to where to look next. No voltage (except at ground points) means NO pressure which means NO current. No voltage = NO current and NO current means whatever is next in the circuit = NO WORKIE!

Solutions (to the limitations of the CLUTCH START SWITCH):

1) BEFORE you have trouble with that switch (90-92 cars primarily), as Jerry Downey said, always depress the clutch pedal completely BEFORE turning the ignition switch. And, RELEASE the START switch BEFORE releasing the clutch peddle. This may avert you ever having to replace that CLUTCH START SWITCH or take other measures...to follow.

2) (90-92 only) Install an auxiliary (high current capacity) relay between the CLUTCH START SWITCH and the starter (see wiring diagram below).

3) (90-92 only) Bypass the (nanny) CLUTCH START SWITCH. The "nanny" part of the CLUTCH START SWITCH is without that switch, the starter can be turned over with the transmission still in gear and the car will lurch when the key is turned to START (which has some advantages too, but a topic for another time).

That only leaves the VATS relay to cause a problem, but that relay is very robust and is seldom the cause of the NO START syndrome.

AND, of course any attempt at troubleshooting begins with verifying that all connections are making good contact - again, the reason for including the typical voltages is provided to aid in the assessment of connections (starting with the battery terminals), among other things.

I created the RELAY diagram back when I first bought my Z and almost immediately experienced NO START issues. As it turned out tho, it was the STARTER SOLENOID contacts that were worn out and needed replacing. But, I then began to have intermittent issues with the CLUTCH START SWITCH.

NOTE: Installing an auxiliary relay (90-92 ZR-1s ONLY) won't fix a bad CLUTCH START SWITCH, nor will it fix BAD starter SOLENOID contacts if either is the problem. The relay will only preserve that switch by vastly reducing the current through the internal switch contacts. IOW, if your CLUTCH START SWITCH is already going bad, adding a relay will not fix it. It either has to be replaced and then install the relay (90-92 only), OR bypass that switch and forget too about adding that auxiliary relay al together!!

Anywayz.... I sincerely hope I didn't confuse the topic further. My intent was the opposite, to "unravel" it (as it were).