at all

 

Im having exactly the same problem right now....Im pretty sure its the VATS module....
The way to know if the problem is the key cylinder: insert the key in the cylinder, then meassure the resitence on the 2 yellow wires that run donw to the steering column (disconnect the plug). If the resistence meassure the same as the key pellet..then your key cylinder is fine.
How do I now that the enable relay is not the problem: I grounded it directly from a ground source...and the engine cranks. Who give ground to the enable relay is the VATS module. Thats why Im thinking is the VATS module.

hope this help.....
post the solution if you find it first.....I will do the same.

 

Rod,hi, someone here addressed before that the starter enable relay comes before the VATS , maybe our VATS is working 50% or so ...because i have fuel , it cranks and starts if i push the starter enable relay tab
i will post the video here

 

Tested a brand new starter relay and same thing happened ...its not the relay
but here's the video

 

Nice to hear your voice.

I don't have my FSM with me here at work, but from what I recall it sounds like you might have an open on circuit 965 (dark green wire) preventing the relay from being enabled. Again, from memory, when you turn your ignition to start the VATS module grounds circuit 965 which enables the relay. If you pull the relay maybe you can use an ohm-meter to check if the green wire is grounded when in the start position.

Wayne


WARNING: THE ELECTRICAL DIAGNOSIS SERVICE MANUAL SUPPLEMENT CLEARLY STATES DO NOT MEASURE RESISTANCE OF THE VATS MODULE.

I am leaving this post to preserve the continuity of our exchange, but please do not do the test I suggested. Sorry, Wayne.

 

Thanks Wayne ! Do i have some accent ? hehe
i have an ohm-meter , how do i check that , thanks !
S

 

Nah...I've been told I have a California accent, though. (I studied Japanese for a while. At the end of a session the teacher said we had to work on my accent---I was picking up a southern Japanese accent from the other teacher I was working with.) But I digress...

The ohm-meter works by applying a small voltage & measuring the current (resistance=Volts/Current). You should be able to check circuit 965 by connecting the ground terminal of the ohm-meter to a chassis ground, the + terminal to the dark green wire (or a pin in the relay socket connected to it). This should be an open circuit (high resistance). When you put the ignition in the start position a transistor in the VATS module should pull the green wire to ground and the resistance should drop noticeably. If you don't see any change at all there is either an open in the wire, a problem in the VATS module, or I'm full of sXXt.

You might want to look at the schematic in the electrical suppliment to double check my theory first (I'll look at it tonight too).

I haven't done this myself but was looking at this circuit a lot trying to understand my VATS problem. I think there are test lights that can be used for this instead of the ohm-meter.

WARNING: THE ELECTRICAL DIAGNOSIS SERVICE MANUAL SUPPLEMENT CLEARLY STATES DO NOT MEASURE RESISTANCE OF THE VATS MODULE.

I am leaving this post to preserve the continuity of our exchange, but please do not do the test I suggested. Sorry, Wayne.

 

aggggggg gets complicated !

 

Sorry, I think my description makes it sound worse than it is:

Pull the relay.

Put the ohm-meter ground connection to a chassis ground.

Put the + terminal to the green wire (or related terminal)

Turn the ignition switch & look to see the resistance go from a high number to a small one. If it doesn't, somethings wrong.

This may take more hands than you have, but is otherwise fairly simple.


P.S. one of the bolt heads I see in your video may work for the ground.

WARNING: THE ELECTRICAL DIAGNOSIS SERVICE MANUAL SUPPLEMENT CLEARLY STATES DO NOT MEASURE RESISTANCE OF THE VATS MODULE.

I am leaving this post to preserve the continuity of our exchange, but please do not do the test I suggested. Sorry, Wayne.

 

You speak very fluent English Sammy.

I will place a bet for $2.00 to You that the problem is the Pass Key Lock Cylinder itself.
Broken Thin White Wire(s) coming out.

I can't even tell you exact how many of those GM Pass Key Lock cylinders I have had to replace in the last 15 - 20 years.
Likely somewhere around 300 - 400 is a safe bet to say.

Back then I was so used to changing out Pass Key 1 Lock Cylinder with thin wires coming out,
I could have the job done in 1 hour or less.

Pass Key 1 was used in hundreds of thousands of other GM vehicles other than a C4 Corvette.

 

Will do this soon, thank you very much !
we might find something there

Brian thanks ! i was trying to look where are the small wires to get them out with the coat hanger but i got really lost btw i was a contorsionist my back hurts a bit ...

 

You may very well be right.

I was thinking of the relay circuit because his injectors are firing suggesting the VATS is happy. When the VATS is happy it enables the injectors and grounds the starter relay. A broken wire as you describe might prevent all this, but I wouldn't think the injectors would be enabled in that case.

 

that's why makes me discard the VATS,the injectors.-
plus the only thing that was unusual was playing with the telescopic adjustment the day before.

 

I am a veteran contortionist myself.
I can lay on my back working under a dashboard for hours & be OK.

When I work on pickups or large semi diesel trucks,
I just sit on the engine.
LOL

I am fit & in very good shape for my age.

I have been switching from diagnosing driveability problems on cars & pickups to working on Semi Diesel trucks all week.

All week long I have been replacing the brakes on Semi tractors & trailers with my boss side by side in the mornings.
From 8- 12 we are done just in time for lunch.

I was beating all the tires & rims off with a 20 lb sledgehammer laying on my back.
Then beating the 90 lb brake drums off.
Its very tiring when you have to swing as hard as you can for almost 20 minutes non- stop to get a stubborn rusted on Giant semi wheel off.
Happened that way a few times this past week.
Boss & I take turns swinging the sledge.

Working like animals.
He tells me he is too old for that chit.........

Remove the front seat from your 87.
Good tip from others here on C4 in the past.
Give you more room to lay on your back then.

I can lay on the rocker panel on my back & be OK working under the dash of my 87.

BR

 

Yeah, both points are compelling.

I just finished work & am heading home. I'll stare at the FSM & electrical suppliment after supper & let you know if I come up with anything.

If you do try the ohm-meter check, be sure you have a good ground. To check that, find two grounds and be sure the ohm-meter indicates a low resistance between them.

 

thanks guys you are great !!!

 

You're welcome Sammy.

Do you have the 1987 Electrical Diagnosis Service Manual Supplement?

If so, please look at the schematic on page 8A-30-0 titled Starter and Charging System Starter. (I tried to scan it but my scanner doesn't work tonight for some reason.)

When you turn the ignition switch to start the battery voltage is fed to the yellow wire (circuit 5) that connects to terminals C and E of the starter enable relay. We know that it reaches terminal E because you can manually close the relay and start the car. If it doesn't reach terminal C then the relay won't function. Maybe this is one of Brian's broken wires?

On page 8A-30-3 there is a section titled System Diagnosis Starter that has a test equivalent to the ohm-meter test I was suggesting. I'll paraphrase it as follows:

With the relay in place, connect the negative terminal of a voltmeter to chassis ground and poke the positive terminal into pin B of the starter relay (the dark green wire, circuit 965).

Turn the ignition switch to start and read the voltage.

If you get the battery voltage then the problem is an open in circuit 965, or a VATS module fault and you go to Section 8A-133.

If you get 0 to 1.5 volts then the problem is in the Ignition Switch (again, Brian's broken wires?) or the starter system itself and you continue with the symptom tables on the following pages.

If you don't have the supplement, I can scan some pages at work Monday.

 

Thank Wayne , yes i have it

 

Yikes!!! I shut off my computer and was taking one last look at the schematic and noticed this by the VATS Decoder Module SOLID STATE DO NOT MEASURE RESISTANCE.

So please follow the test on page 8A-30-3 and do not do the ohm-meter test.

I will add a similar warning to my earlier posts.

 

nice to see you solved your problem......Im still trying to solve it!!