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Paul Workman · 06-23-2014

In ALL ZR-1s the clutch relay carries all the current drawn by the starter solenoid - a few amps. However, only on the 90-92s does the clutch switch carry the entire current to operate the starter solenoid. On the 93-95s the clutch switch enables the clutch relay (via the CCM), thus reducing the amperage load and the arching that erodes the clutch switch contact points (only) significantly.

So, it might be a good idea to have a clutch start relay (and possibly some others too) in the glove box, along with an assortment of fuses too, just in case.

90-92 Clutch schematic(1)

93-95 Clutch scematic(1)

On this topic, Scottfab pointed out that arching can be reduced in the clutch switch IF the clutch is fully engaged before, during, and after the starter is engaged vs. turning the switch to START and then engaging the clutch switch...especially on a 90-92 car.

Although the clutch switch is redundant to those of us taught to engage the clutch first any time the starter is engaged, I think it is important to have it in working order as a hedge against the unexpected - who knows what!?

Essentially converting the clutch switch to the role played by the 93-95 cars is accomplished in a 90-92 car by installing a relay between the clutch switch and the starter solenoid. This way the relatively large solenoid current is isolated from both the start relay and the clutch switch - truly a mod worth considering to improve reliability of both the clutch relay (all cars) and the clutch switch in 90-92 cars.

Locating this relay near the fused link post (under the battery) provides a convenient location to access battery power for the starter solenoid path through the new relay. And, installing its own socket for the new relay allows for quick replacement, should it be needed.

Paul
___________

ref:
(1) Marc Haibeck article posted in HOTB.

06-23-2014	#12
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: Bypassing the clutch switch In *ALL* ZR-1s the clutch relay carries all the current drawn by the starter solenoid - a few amps. However, only on the 90-92s does the clutch switch carry the entire current to operate the starter solenoid. On the 93-95s the clutch switch enables the clutch relay (via the CCM), thus reducing the amperage load and the arching that erodes the clutch switch contact points (only) significantly. *So, it might be a good idea to have a clutch start relay (and possibly some others too) in the glove box, along with an assortment of fuses too, just in case.* 90-92 Clutch schematic(1) 93-95 Clutch scematic(1) On this topic, Scottfab pointed out that arching can be reduced in the clutch switch IF the clutch is fully engaged before, during, and after the starter is engaged vs. turning the switch to START and then engaging the clutch switch...especially on a 90-92 car. Although the clutch switch is redundant to those of us taught to engage the clutch first any time the starter is engaged, I think it is important to have it in working order as a hedge against the unexpected - who knows what!? Essentially converting the clutch switch to the role played by the 93-95 cars is accomplished in a 90-92 car by installing a relay between the clutch switch and the starter solenoid. This way the relatively large solenoid current is isolated from both the start relay and the clutch switch - truly a mod worth considering to improve reliability of both the clutch relay (all cars) and the clutch switch in 90-92 cars. Locating this relay near the fused link post (under the battery) provides a convenient location to access battery power for the starter solenoid path through the new relay. And, installing its own socket for the new relay allows for quick replacement, should it be needed. Paul ___________ ref: (1) Marc Haibeck article posted in HOTB. Last edited by Paul Workman; 06-23-2014 at 09:15 AM.