Intermittent DNS

[ALLTHECAMS]

So I now have the intermittent DNS (dreaded no start) on my 91 Z. I want to try to bypass the clutch safety switch to see if that helps. Can I just unplug it and jumper across the plug or is there more to it?

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[-=Jeff=-]

Is it DNS when hot only? If so.. starter contacts


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[QB93Z]

Verify that both battery terminals are clean and tight. Disconnect any after market systems attached to the battery terminals.

Put the ignition key to ON, Engine not started. Note the battery voltage on the instrument panel. Turn the key to start, while watching the battery voltage meter. If the needle does not deflect, then investigate the starting circuit, ie clutch switch, VATS, TDS.

If the volt meter does deflect, it means that the starter solenoid is energizing but the solenoid contacts are not passing current to the starter motor. Rebuild the starter solenoid or replace the starter.

NOTE, keep this procedure handy because it has to be done when the car won't crank. For an intermittent problem like you stated, you will have to wait until the next failure.

Good luck,

Jim

[ALLTHECAMS]

Is it DNS when hot only? If so.. starter contacts


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Yes so far its only when hot and not every time. Thanks for the advice. Hoping I don't have to pull the plenum again.

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[RICHARD TILL]

EXACTLY the same symptoms I had when the starter solenoid contacts were dirty.

[ALLTHECAMS]

OK, so it happened again. I watched the volt meter and the needle didn't move when I turned the key to start. I was able to get a push start. What's the next step?

[QB93Z]

TDS is the theft deterrent system, the resistance chip in the ignition key that is checked to allow the computer to allow the starter circuit to energize.


The next step is to rebuild the starter solenoid or replace the starter.


Jim

[ALLTHECAMS]

TDS is the theft deterrent system, the resistance chip in the ignition key that is checked to allow the computer to allow the starter circuit to energize.


The next step is to rebuild the starter solenoid or replace the starter.


Jim
OK now I'm confused LOL. In your first post you said if the needle did t move it wasn't the starter but to into the clutch safety switch or VATS? Sorry but I'm a dummy when it comes to diagnosing electrical issues.

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[-=Jeff=-]

If it is Hot start only, it is the contacts of the solenoid. I chnaged the wiring a bit to minimize the solenoid electrical path, I still ended up pulling the starter and replacing the contacts.. The Challenge is diagnosing while hot..

But because it is only when hot, the contacts make more sense than the clutch switch

[ALLTHECAMS]

If it is Hot start only, it is the contacts of the solenoid. I chnaged the wiring a bit to minimize the solenoid electrical path, I still ended up pulling the starter and replacing the contacts.. The Challenge is diagnosing while hot..

But because it is only when hot, the contacts make more sense than the clutch switch
OK thanks

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[Kevin]

If you need a how to on bypassing the clutch switch I can post it when I get home from work tonight.

[QB93Z]

OK now I'm confused LOL. In your first post you said if the needle did t move it wasn't the starter but to into the clutch safety switch or VATS? Sorry but I'm a dummy when it comes to diagnosing electrical issues.



You are correct. I am on the road in Colorado right now and wasn't following you comments carefully enough. I suggest troubleshooting the starter circuit to identify a switch or wiring that is failing. I don't have any manuals with me so I will leave the explanation to others.


Jim

[Z51JEFF]

Bypassing the switch is easy. Pull the hush panel and look up under the dash and look for the 10 gauge PURPLE WIRE plug,it should be towards left of the steering column. I have a jumper I made,if you were closer I'd loan it to you for some trouble shooting.

[ALLTHECAMS]

Bypassing the switch is easy. Pull the hush panel and look up under the dash and look for the 10 gauge PURPLE WIRE plug,it should be towards left of the steering column. I have a jumper I made,if you were closer I'd loan it to you for some trouble shooting.
Jumper across the plug then?

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[5ABI VT]

Might not be much use but I posted my experience here :
http://www.zr1.net/forum/showthread.php?t=26832

Check out post #53 I posted a photo of the clutch switch on my 94. Just thought I would add that because I jumpered the wrong switch early and chased my tail for a while before I realized it.

[Z51JEFF]

Jumper across the plug then?

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Yes. I've got a new switch but when the time comes to replace it I'll bypass it,too much of a hassle to get to the switch.

[ALLTHECAMS]

So a couple weeks ago I had the DNS again. I replaced the battery and ran a bypass on the clutch safety switch and thought I had solved the problem. WRONG!!

This morning when I got in the car to go to a show I turned the key and no crank. I tried jumping it on both my pickup and a battery charger, waiting 5-10 minutes between each attempt. Then I ran a jumper between the purple wire and the VATS lockout relay. It will crank but will not fire. I have fuel pressure in the rails, plenty of voltage at the battery, but I dont know if the injectors are firing or if I have spark. When I crank it the tach needle comes off its stop but only shows 0.

it is difficult alot of times to turn the key cylinder back so I can get my key out.
Help!!! This is my dream car, but I've never had a car this unreliable.

[ALLTHECAMS]

Anyone??

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[Ccmano]

Pull a spark plug wire then crank it with a plug checker or just a screwdriver to ground and see it you have spark. If no spark I'll bet it's a VATS issue.


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[Z51JEFF]

One other option is to put a secondary relay in for the starter,check out sticky thread in the ZR-1 second on the other site.

[ALLTHECAMS]

I have spark. 45-50 psi fuel pressure. It actually started when I was working on it today. I test drove and started it 3 more times once I got home. I put the dash back together and it wouldn't start again.

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[5ABI VT]

I did not go back and read the rest but is vats still active ? Have you tried both keys if you have them? When my clutch switch went I went ahead and added the resistor to by pass the pellet on the key

[ALLTHECAMS]

I did not go back and read the rest but is vats still active ? Have you tried both keys if you have them? When my clutch switch went I went ahead and added the resistor to by pass the pellet on the key
I only have one key. I ran a jumper from the purple wire on the clutch safety to one of the yellow wires on the VATS lockout. According to instructions on the main page of this site that should bypass both clutch safety and VATS. I have a friend that used to work for Ripple and he thinks its a fuel issue. I just remembered I had a similar issue on an IROC I had and it was the fuel pump relay.

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[karlaw]

Where is VATS lockout located ? Is it possible to completely eliminate the entire VATS and TDS ?
I have been fighting DNS for 2 years now, on 2 1990 cars. New batteries, both new fuel pumps, bypassing VATS at bottom of steering column, TPS has .45 volts.
On my red car, key on, under hood use jumper from battery to the larger purple wire to engage starter, ....car cranks and car fires and tries to run for 3 seconds then dies. Subsequent tries car will not fire, unless turn key off and wait 10 minutes, then it will fire once only, then key off and wait again.
My vacuum pump not working. Car has spark on all 8.
Please, any help ideas ?


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[karlaw]

I bought a $30 cheap code reader from auto value, but only code I can get is code 12.


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[ALLTHECAMS]

I haven't had any issues since I bypassed VATS at the bottom of the column. Maybe someone else knows?

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