No starter?
Thread Starter
Intermediate
Joined: Jan 2013
Posts: 47
Likes: 0
From: Leominster MA
No starter?
Somewhat suddenly I've been getting an intermittent problem. I'll hop in, turn the key and --- nothing. Each time I've jiggled wires, run the key in and out, still nothing. It strikes me that my voltage looks to be reading a bit low so I assume a short and disconnect the battery to hook up an ammeter. It shows zilch. Then I reconnect the battery and voila, it starts.
Sure doesn't smell like a starter problem or a power-wire issue. Is there anything in the eprom that might cause such a condition? The only thing I recall changing is the vats diag flag, which I put 'on' for no particular reason. Anything else jump out at anybody?
Sure doesn't smell like a starter problem or a power-wire issue. Is there anything in the eprom that might cause such a condition? The only thing I recall changing is the vats diag flag, which I put 'on' for no particular reason. Anything else jump out at anybody?
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Somewhat suddenly I've been getting an intermittent problem. I'll hop in, turn the key and --- nothing. Each time I've jiggled wires, run the key in and out, still nothing. It strikes me that my voltage looks to be reading a bit low so I assume a short and disconnect the battery to hook up an ammeter. It shows zilch. Then I reconnect the battery and voila, it starts.
Sure doesn't smell like a starter problem or a power-wire issue. Is there anything in the eprom that might cause such a condition? The only thing I recall changing is the vats diag flag, which I put 'on' for no particular reason. Anything else jump out at anybody?
Sure doesn't smell like a starter problem or a power-wire issue. Is there anything in the eprom that might cause such a condition? The only thing I recall changing is the vats diag flag, which I put 'on' for no particular reason. Anything else jump out at anybody?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The VATS system also has a starter enable relay located behind the DIC in the center cluster. Even if the engine doesn't crank you should hear that relay clicking when you turn the key to the start position.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Okay, before digging into the VATS, there's a couple of simple things that may help point you in the right direction.
First, when this happens, and you turn the key, do you still have all the lights and guages active on the DIC?
If it's all black, then it's a power supply issue. I had this and it turned out to be the terminals (posts) on the battery cable.
Second, and I am not familiar with the DIC on the '86, but is there a security light on the DIC? If so, when you turn the key, and the VATS is activated, (not supplying power to ignition and fuel) the light should be on. If the light is off, then VATS is not likely the problem. But try cleaning the pellet on the key with some denatured alcohol, it has worked for me the couple of times my VATS acted up.
Also check connection to starter solenoid, or the solenoid itself may be goig out.
BTW, the computer really doesn't have anything to do with this, as this is pretty much simple electronics. The pellet is basically a resistor that closes a circuit to the ignition system. The computer is pretty much in charge after the car starts.
First, when this happens, and you turn the key, do you still have all the lights and guages active on the DIC?
If it's all black, then it's a power supply issue. I had this and it turned out to be the terminals (posts) on the battery cable.
Second, and I am not familiar with the DIC on the '86, but is there a security light on the DIC? If so, when you turn the key, and the VATS is activated, (not supplying power to ignition and fuel) the light should be on. If the light is off, then VATS is not likely the problem. But try cleaning the pellet on the key with some denatured alcohol, it has worked for me the couple of times my VATS acted up.
Also check connection to starter solenoid, or the solenoid itself may be goig out.
BTW, the computer really doesn't have anything to do with this, as this is pretty much simple electronics. The pellet is basically a resistor that closes a circuit to the ignition system. The computer is pretty much in charge after the car starts.
Thread Starter
Intermediate
Joined: Jan 2013
Posts: 47
Likes: 0
From: Leominster MA
A bit more info... yes, the DIC comes on when the key hits 'on'. I can also hear the fuel pump run. But when I hit 'start', nothing happens, no solenoid, no click in the dash. It does sound from the info given like the vats. Not sure how setting 'vats diag' would change that since vats itself has always been enabled, but it wasn't set before so I changed it back. BTW I'm running modded apyp if that's any factor.
The fact that reinitializing the ecm seems to cure the condition steers me away from a pure electrical issue (please) toward the programming, but I'll check further and report back what I find, if anything. Thanks to all for the info!
The fact that reinitializing the ecm seems to cure the condition steers me away from a pure electrical issue (please) toward the programming, but I'll check further and report back what I find, if anything. Thanks to all for the info!
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
Turn off the 2 vats flags in the programming, and see if it goes away. If not, it's either a fault in the vats module, and the starter enable relay. Grounding the yellow wire to the relay will bypass it assuming the relay is good.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Second, and I am not familiar with the DIC on the '86, but is there a security light on the DIC? If so, when you turn the key, and the VATS is activated, (not supplying power to ignition and fuel) the light should be on. If the light is off, then VATS is not likely the problem.
The functions of the VATS module were moved into the CCM in later years. Early '90s -- I don't know exactly when it happened.
Thread Starter
Intermediate
Joined: Jan 2013
Posts: 47
Likes: 0
From: Leominster MA
Just an update --- happened again. Of course it totally slipped my mind to try the other key which was about 10 feet away (*think* I tried that before, but not sure), but at least I did try something new. Rather than disconnect/reconnect the battery like before, I burned a new chip with vats disabled (before, just vats diags were disabled). Swapped chips and it fired right up. I'll post new info when I have some. And thanks for all the info!
Thread Starter
Intermediate
Joined: Jan 2013
Posts: 47
Likes: 0
From: Leominster MA
Some followup here. Since my last post I had no problem (VATS shut off) and then, today, voila, it was back. I opened the hood to look for something. Then it started. Closed the hood. Wouldn't start. Opened it again. Started again. This is getting stupid.
One thing I did want to mention... I put the AC on when I turned the key to 'on' in one test where it was failing. When I cranked the key to 'start', I could hear the fan I have wired to the compressor (so it runs when the clutch is engaged) shut down. I assume that and other stuff shuts off to save power for the starter. The starter itself did nothing. Does that tell me roughly where in the electrical path I have an issue? Like way past the VATS relay? Maybe directly on the starter wiring?
One thing I did want to mention... I put the AC on when I turned the key to 'on' in one test where it was failing. When I cranked the key to 'start', I could hear the fan I have wired to the compressor (so it runs when the clutch is engaged) shut down. I assume that and other stuff shuts off to save power for the starter. The starter itself did nothing. Does that tell me roughly where in the electrical path I have an issue? Like way past the VATS relay? Maybe directly on the starter wiring?
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Disabling VATS on the tune has no bearing on the VATS operated relay which enables the starter.
All it does is remove the requirement for the ECM to get the fuel enable signal from the VATS module before it will pulse the injectors
Read
http://www.thirdgen.org/vats_passkey_system
for a better understanding
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
the car has been cranking fine since you did the chip
you have a intermittent fault either
1.a key not being read correctly by the VATS module
2.a faulty VATS module not operating the relay
3.a faulty enable relay
Last edited by vetteoz; Oct 8, 2013 at 10:48 PM.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Since you have disabled VATS in the tune the 1st thing would do is bypass the redundant enable relay as a potential fail point.
Typical early C4 circuit shown , yours has a " enable " relay in place of the 84/85 " interrupt" relay shown
Thread Starter
Intermediate
Joined: Jan 2013
Posts: 47
Likes: 0
From: Leominster MA
Great info, Oz. Now I'm armed for some half-intelligent testing. Just looking at these diagrams has me thinking about bypassing all this multiple-failure-point crap and just installing a hidden disable switch somewhere!