Bypassing the clutch switch

[max76]

Hi guys...after bypass the clutch switch is better change the starter enable relay?
how i can check if it's good or not?
Thanks in advance!!!
Max

[Paul Workman]

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.

[Dynomite]

Originally Posted by Paul Workman

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.

On the Early 1990s the wire to cut is RED (there is no 12 gauge purple wire)

Starter Relay, Wiring Harness, and Plugs Tricks

I locate the Relay UNDER the ECM which is right next to the wire harness/wire to be cut.

60 / 80 AMP RELAY SPDT SINGLE POLE DOUBLE THROW NEW 654
Installed under ECM and in slot between brake booster and fire wall (perfect place for location of Relay).

Wiring modified a bit to assure Pin #87a is not hot at any time.
Pin #30: Purple wire to starter (use 3/8 inch connector on relay).
Pin #87: Red wire battery positive 12v use 3/8 inch connector on relay (connected to battery positive multiple connection post).
Pin #86: Battery ground (1/4 inch connector on relay connected to ground where battery 12 gauge wire grounded).
Pin #85: Purple wire from ECM use 1/4 inch connector on relay (Red wire on early 1990 ZR-1).
Pin #87a: Not hot at any time and not used.



Insert a short 1/2 inch long section of plastic hose
over the center connector on the Relay which is NOT
used in this application.

[Dynomite]

Paul.....what is the Bold Red Line? I am assuming that depicts the current path through the relay we install without showing the relay?
Nice diagram.....
thanks,
Cliff

Originally Posted by Paul Workman

90-92 Clutch schematic(1)


Paul
___________

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

If it were not for the fact the LT5 starter is buried deep under the Plenum, refurbishing the starter Solenoid would be a piece of cake.

Starter Contacts.
The Starter Solenoid is shown in the left photo with slight burnt contacts in right photo.

The Solenoid contacts in left photo were wire brushed clean in right photo.