No Start ......Again

Dave91TM

Dave91TM

Power User
2 You're 10
May 14, 2011
2,050
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Barrie Ontario
VetteCoins
78,523
Car
1991 Coupe
I thought I had this fixed. Its the famous intermittent no start game. Car acted up a few time in last couple of years .Afetr a new ignition cylinder and a NEWROCKIES module to totally bypass the VTAS system all was good until today. Same old thing , lots of power, no fuel pump, no starter. The car is a 1991

I'd like to try and by pass the clutch safety switch, but I cannot find a wiring diagram. On visual there is only only one black switch on the clutch lever, connected with brown-white stripe and a grey -brown stripe.

Thats as far as I got. any help anyone?
 
Hey Dave,

Older GM's such as the C4 have a high amperage clutch safety switch which feeds the solenoid. Usually there is two wires coming out of the switch (yellow and purple). Jump the two wires together and give it a crank and see.

Ryan
 
Hello Ryan
Thanks for the quick reply. Believe it or not I just tried it again and it started like it was brand new. I even tried the blank key with no resistors and it started fine. At least I know its not the VATS or the by pass module. There are purple and yellow wires but they are not connected to the switch on the clutch lever. They are joined at a coupling but do not seem to have anything to do with the clutch. Obviously I am not sure what I am doing. Can you be a bit more specific ? BTW my cheap Haynes manual has some wiring diagrams but nowhere is there yellow and purple wires... go figure.
 
Hey Dave,

If you look up directly above the clutch pedal (along the shaft), you should see a contact plate that will press against the switch when the clutch is depressed. Out of that switch should be the two wires that you are after. Jumping the two wires will bypass the switch. You can also feed +12V to the purple (if I remember correctly, it's been a few years) line and spin the starter regardless of the position the key is in, however it won't actually start unless the key is in the ignition on position. I'll see if I can find some pictures that may help you out along the way.

Ryan
 
harness.jpg


This is the only photo that I could find in a quick google search. This is the harness that plugs into the wiring from the clutch safety switch. The yellow wire comes from the ignition switch, and the purple feeds the relay that closes the solenoid for the starter. Hope that helps....................

Ryan
 
Rub A535 is your friend after a day under the dash.:Biggrin:

Wish you the best determining your problem. Wiring is the thing I fear the most but in this case Ryan seems to point to a possible solution. Good luck.:thumbs:
 
Hi Guys... that went well, Thanks for your help.

Of course though I had to go a bit further and check out the wonky turn signal. here is what I learned
1. don't remove the plastic covers on the steering shaft. one of them holds the high beam operating slider in place
and you cannot put it back together unless you remove the steering wheel.
2. in order to work under the dash, remove the drivers seat entirely. Then place some heavy cardboard over the seat frame
and crawl in so you can lay on your back with your feet in the hatch. You can lay there and work for hours. I know , I just did.

Anyway, off to buy a new turn signal switch and proceed to that replacement.

Its a good thing half the fun of vette ownership is fixing it.
 
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Todays lesson is you can put it back together without removing the steering wheel. The trick is that the steering column
has to be horizontal, not tilted up. if horizontal the plastic piece that goes in between the turn lever and the operating rod
will stay in place. Then you ask your favorite wife to give you a hand as you need to hold the turn signal lever up to get enough clearance to wiggle in the plastic cover, all of course while laying under the dash. I pass this information on and am now going for a nap and hope I do not seize up from the contortions recently performed.
 
Hi Graham

I bypassed the clutch safety switch. It was actually quite simple just separate the connector and insert a loop of heavy wire across
the purple and yellow wire pins. Car will start without depressing clutch. Besides that, it wouldn't be too simple to get at the actual switch,
its way up under the dash behind a number of wiring harnesses. Very simple to wire back if needed.

If we get another no start episode, at least we 'll have one less variable.
 
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Hi Nelson
Don't think its the starter. When it decides not to start, there is no power to either the fuel pump or the starter. The only things I know that would cause this are faulty ignition cylinder at key, faulty key ,VATS lost its mind and/or clutch not depressed. As noted prior I have now replaced the ignition cylinder with new keys, bypassed both the vats and the clutch thing and it started like a charm today.

If it happens again, I'll be looking for help.
 
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