Z won't start

[Jetjock]

I went out to my garage to move my 93Z to do some work and the carwon't start. I had this problem before but always able to get the car started. I suspect the clutch safety switch is the culprit. I have the part but was wondering if anyone ever changed one out or did something else.


Thanks for any input.


Roy

[Ccmano]

Define “won’t start”. Turn the key, nothing happens. Or engine turns over but won’t start? If it’s the first, item one to check is the battery. If the resting voltage is anything less than ~12.4 volts the battery is suspect. Have it checked with a proper “load” test. There are many other conclusions you can jump to but more often than not it’s simply the batter or connections.
H

[Jetjock]

Originally Posted by Ccmano

Define “won’t start”. Turn the key, nothing happens. Or engine turns over but won’t start? If it’s the first, item one to check is the battery. If the resting voltage is anything less than ~12.4 volts the battery is suspect. Have it checked with a proper “load” test. There are many other conclusions you can jump to but more often than not it’s simply the batter or connections.
H

I wrote a response to defination; however, my computer signed me out before I could post it. Bottomline, the battery is new and is on a battery tender. I had over 12 volts. There was no sound like the starter or the engine trying to turn over. It wasn't the VATS. I had this clutch safety switch go bad on my 92Z and I bypassed it and haven't had a problem with it since. I did the same with the 93Z but it hasn't worked that well. I am exploring other considerations.


Roy

[Ccmano]

Roy,
Please double check your battery for the voltage I noted above before you go any further. Just because the battery is new and on a tender in no guarantee. I’ve seen stranger things. If the battery is good the issue is likely the starter solenoid. The contacts corrode/burn even on low mileage cars. Do a search on starter solenoid and you’ll find volumes. Also, the excellent “Solutions” sticky at the top of this section has a complete run down.
H

[oldpro]

Here is the way to fond out if it is your clutch switch . Push the clutch in and watch the battery gauge on the dash panel if the needle moves when you try to start then it's the starter if it doesn't move its the switch hope this helps

[Jetjock]

Originally Posted by oldpro

Here is the way to fond out if it is your clutch switch . Push the clutch in and watch the battery gauge on the dash panel if the needle moves when you try to start then it's the starter if it doesn't move its the switch hope this helps

I went out to the car as soon as I saw this post. The needle did not move at all until after several attempts, it twitched. The digital readout did not change until after several attempts. It then jumped up in voltage and then back down. Could it be both?


Roy

[oldpro]

Hmm sounds like you have a problem. With the clutch switch like a bad contact causing voltage to behave erractiy : if it were me I would either bypass the switch or put a new switch first if that doesn't work then it pull the plenum and ck the starter out

[Paul Workman]

Some 93-95 specific circuit diagram my shed some light on the issue?

First...the high current (arching) that eventually eroded the contacts of the (90-92 model years) clutch safety switch (that was in series with the starter circuit) was fixed in the 93-95 ZR-1s (see the switch, circled in RED, in the GREEN circuit path).

The current and so too the erosion due to arching is all but eliminated from '93+ ZR-1s. So, if there is intermittent issues with the starter not turning, chances are it is much more likely an issue with erosion of the internal SOLENOID CONTACTS inside the starter solenoid housing (likely) or the START ENABLE RELAY (rarely the likely problem).

First things first: you can eliminate the clutch safety switch as being the issue by temporarily connecting the two ends of the wires leading to/from the clutch safety switch. It is doubtful that on a 93+ ZR-1 that you'd notice much if any change to the problem's characteristics. But, if the starter issue is resolved - never to return - then it was that clutch safety switch perhaps after all that needs to be replaced. HOWEVER, if there's no change to the starter characteristics, leave the clutch safety switch bypass intact for now, and try to next identify which relay(s) may be the problem. Read on...

To eliminate the (very unlikely) STARTER CONTROL RELAY, probe the large purple wire leading to the STARTER SOLENOID and monitor the voltage on a VOM as you turn the ignition switch to START.

If the voltage immediately reads battery voltage OR SLIGHTLY LESS than what the battery reading was when everything (except the under hood lights) are at rest, the problem is @ the starter. Off with the plenum! But, if a NO VOLTAGE reading ensues with the ignition switch in the START position, then either the problem is with the STARTER ENABLE RELAY UNLESS there is an issue @ the CENTRAL CONTROL MODULE where it is not grounding the ENABLE relay for some reason e/g., is the SECURITY light flashing with the door closed??

If you observed the battery voltage on the dashboard as you turn the ignition switch to START, if the voltage dips slightly, the problem may be a defective solenoid coil or other internal starter winding issue (shorted). But, if there is no dip in the dashboard volt meter when you roll the ignition switch to START position, then it is likely the relay contacts in the starter solenoid - good news b/c it is usually around only $10 to replace the contacts.

(NOTE: I've said this many times before, but the more expensive solenoid repair kit for the Denso starter usually includes a new solenoid armature. Compare the length of the new armature plunger pin with the OEM part. I have found it may have a shorter plunger pin than the stock solenoid armature has. If so, DO NOT install that part. Instead, brighten up the contact ring with fine sandpaper and reuse the stock solenoid armature. To use the replacement part with a shorter plunge pin will result in only a portion of the contact area between the pinion and the flywheel ring gear. Eventually, this will result in excessive wear at the least. Or worse, it may lead to missing teeth on the ring gear...no bueno

[oldpro]

Great explanation Paul I learned a lot from your post .

[RussMcB]

There is a "purple wire mod" discussed occasionally in ZR1.net. It allows you to make a more direct connection between the battery and starter, bypassing the clutch switch, VATS and ignition switch (sort of). It includes a relay that uses the signal from the ignition switch to send a strong 12v directly from the battery. A search should bring up details. It worked for me in 2015 and has been on my car since with no more no-start issues. Before then I tried the VATS bypass but it didn't help.