TrevinE

I have a 1990 Iroc convertible. All stock with 45,000 miles. I have been having some very big frustrations trying to get this starting issue resolved. Up until this weekend, I was convinced it was the vats system. Sometimes the car will start right away and sometimes it won’t. Until now, if the car won’t start, I would let it sit 5-7 minutes, turn the key, and violla, it would start. This weekend, it would not start at all. Tried letting it sit several times, and even removed the battery cables for a few minutes and still nothing.. So far, I have replaced the keys and the ignition tumbler with brand new parts ( prior to this weekend).

Any other thoughts?

Thanks

Tuned Performance

iTrader: (92)

The letting it sit for awhile sounds like a bad icm or pu coil. When it acts up is it a no crank issue ?

TrevinE

When it doesn’t start, everything seems normal. Lights works, accessories work, and you can even hear the starter solenoid activating. It just won’t crank.

Tuned Performance

iTrader: (92)

Sounds like a vats issue. To test (Tpi)f10 blue wire of the ecm should have 2.5v or a 30-50hz signal if the passkey is working correctly.

red rock

iTrader: (2)

It could be many possibilities, but you want to check the basics first. Start with checking and cleaning the battery connections if you haven't already. Then check the battery ground connection by the alternator. Then check the ground connections on the back of the heads. If you know how to use a multi meter, that can be your best friend on electrical issues. Dirty or loose ground connections can cause an intermittent problem.

tealman92

When it won't start is your security light on or does it go off?
most vats issues is due to the 2 little white wires that connect to the ignition tumbler break and no longer make full contact. Remedy is to replace the tumbler and have a new key cut.
But if your security light goes off when it won't start then vats isn't the problem.

1992 Trans Am

iTrader: (2)

Usually if The VATS box is no good, the car won't even crank and it's not an intermittent problem. The car is basically dead if the VATS box is inop.

1992 Trans Am

iTrader: (2)

I'd check the coil and ignition system too.

TrevinE

I am game to try anything a this point. It's definitely an intermittent problems. I just walked outside and it started right up. Seeing how i have already replaced the key tumbler and keys, are the ignition and coil something i can check. If so how?

Tuned Performance

iTrader: (92)

http://easyautodiagnostics.com/gm/4....ed-icm-tests-1
To test injector pulse you can use a noid light. Check spark first if you have spark and no injector pulse it’s more than likely vats.

red rock

iTrader: (2)

Not sure if you read my post #5 or not, but I'm here to tell you, years ago I had a Dodge work van that would only start when it wanted to. The company kept taking it back to the dealer and it would either start many times or sometimes it wouldn't. With hundreds of dollars thrown at it, finally the dealer put an old experience mechanic on it, and he found the battery ground cable was loose and corroded on the chassis. Anything electrical will not work without proper grounding.

TrevinE

nit when it acts up, it won’t even crank or try and turn over. Everything else seems normal but no engine activity.

TrevinE

i will give the ground a good look. Thanks

NINÅ

Ron U.S.M.C.

Remove the Starter Enable Relay and Bypass it using its connector in the driver-side kick panel by your left foot like in this photo. That will stop VATS from blocking the starter from turning over.


I had a bad VATS Module and it was intermittent. This was part of the fix.

Its the two outside slots. Use heavy gauge wire like in the photo , male spade connectors and tape it all with electrical tape to keep it together and safe.

Be careful because there is a lot of amperage going through it when you turn the key.

Vats will still be able to shut down the injectors so that will also need to be addressed as well but this is a good start.

Also if VATS is activated it will lock you out for about 5 minutes between each start attempt.

TrevinE

Grounds and wires look good. Thinking about ordering a Starter Enable Relay and a Neutral Safety switch. Both are cheap parts and after doing some research, the Starter Enable Really seems to be a fairly common failure too.

What is the part number for the VATS module and where is it located?

Keep the idea coming.

Thanks

Cheerio

iTrader: (1)

I had a similar issue on mine. it would work fine. when you turned it off it would not start back up. I had to wait before turning it back on. I also noticed going over certain bumps the car would loose power. I took it to a mechanic to get the starter replaced and was told that the starter was fine, it just had a loose wire. they tightened it down and has been fine ever since. at first I though it was the vats because when I turned the key nothing would happen. only the SES light and security light would come on. I also noticed that when the car would not want to start I could slam the hood a couple of times and it would start up fine.

2mnytys

I am having a similar problem. When you turn the car over most of the time it starts. When it doesn't it has a sound of a load clicking relay engaging. I can't tell where it is coming from by myself. Maybe also the starter enable relay? VATS light off. I will start on the next key turn or maybe the second.

TrevinE

Sounds the same to me but i have always forgotten to watch the security light to see what it does because i don't drive it very often and forget. Please post up if you find a solution and i will do the same.

Thanks

B1CrwDwg

Following this thread...Having the same issue...been through all the leads, disconnected and cleaned, new battery, new starter relay, new starter and solenoid. HELP!!!

B1CrwDwg

Found my fault at the starter to engine mating surfaces NOT conducting effective ground. Thoroughly cleaned mating surfaces and BAM back in business.

red rock

iTrader: (2)

Dirty old grounds.

TrevinE

Thanks for this. I guess it can be anything at this point.

The saga continues. I was feeling pretty motivated today so i did a complete clay bar and polish followed by a coating of CQUARTZ. SHE looked so good i said i will take her for a ride. I started her 3 times off and on before i drove and zero issues. When i returned, I turned it off and restarted it....no problem. I immediately tried a second time and nothing. At least at this point i think its not the vats. The security light does its blinking thing then goes off.

I tried the bypass thing USMC suggested and it didn't help at all. I have 10.6V going across the starter enable relay with the jumper wire.

The ignition works and the accessories come on when i turn the key to the first position. However, when i try and restart i hear what sound like maybe the fuel pump but NOTHING else. No clicks or anything. I am wondering if it can be as simple as a bad starter but its just so intermittent. It seems to only act up after driving it. I cant say that i have ever recalled in doing it on initial start.

Any other thoughts?????

red rock

iTrader: (2)

Circuits tend to go open when they get warm or hot creating an intermittent problem.

B1CrwDwg

Mine was very intermittent as well...didn’t matter with the engine hot or cold. Only thing consistent was the single click.

TrevinE

well...KNOCK ON WOOD I might have solved this issue. It appears i might have had 2 things going on. The VATS system security light doesn't come on any more when it doest start since I got new keys AND change the key tumbler. The intermittent not starting at all seems to have been due to the starter getting too hot. I noticed that when it wouldn't restart for a long time, it was after driving it. With everything else suggested turning up empty, i started thinking it might be a starter issue even though i have never experienced an intermittent starter issue. Looking at the starter closer, it seemed logical since the engine is above it and the exhaust cross pipe is below it so i thought, "what the hell, lets change the starter and see what happens". I swapped it out and had the car sitting in the shop running for about 20 minutes just to get a nice heat soak going. It was long enough where the aux fans were cycling so i felt it should be a fair representation IF it was a heat issue. After running it, i cycled the key on and off about 5 times and it cranked every time. The true test will be after running it a few times which i will do once the weather clears around here but so far, i am optimistic.

sharky55

So did the new starter do the trick? I am having similar intermittent starting problems. Currently looking at the possibility of bad battery cables. Thought I fixed the problem twice already...the first time by cleaning terminal connections at the starter and the second time by thoroughly cleaning the negative cable to engine block connection which was fairly dirty. After each time, I had success but just today, it failed to start again....tried four times and then by chance it worked the fifth time. Once when it was completely dead for a while and I was testing things, I heard the lights come on (with the key in accessory) when I jiggled the cable at the starter. My starter is very old (15 years or so) but only has like 15K miles of usage. I have had the car garaged mostly...

Cheerio

iTrader: (1)

I had that issue with mine. It ended up being a loose connection on the starter. I would turn the key and nothing would happen. Then hours later it would work fine. Sometimes over bumps the car would want to die.

B1CrwDwg

sharky55

I was looking at this possibility as well but it seems as though the starter is just bolted to the undercarriage and I could not actually find a ground wire connection. Did you just unbolt the starter and clean that connection point?

rarebmx

iTrader: (6)

I have an 89 doing exactly the same, except it is constantly not cranking but everything else works...following. need to find the solution

Tuned Performance

iTrader: (92)

tom3

Is the security light turning off? Should come on for a few seconds, then turn off. If not you probably have a VATS problem. If the light is working right try turning on the headlights (pull some current) then try the starter. If the lights go out and stay out you have a bad connection on the main battery cables.

rarebmx

iTrader: (6)

when this OP thread is solved I need to hijack it.

red rock

iTrader: (2)

Oh heck, hijack it anyway. We can work on multiple issues. Haven't heard from the op since post #26 over a year ago. He may have fixed it.

rarebmx

iTrader: (6)

having basically the same issue. Was working flawlessly then one day tried starting the car. NOTHING. No crank at all. Security light was off. Happened just like when my NSS went out.
I swapped the starter, jumped the nuetral safety switch (NSS), installed new NSS for my other IROC. Swapped new starter & solenoid. Jumped VATS as shown in other threads (that made the security light stay on when key was inserted but still nothing. All battery connections good & was on a charger (strong battery). Had new key cut with correct chipset (tested & bought years ago).
I'm at a loss. Guessing time for a test light to see why no juice is getting to the starter.

red rock

iTrader: (2)

Have you tested with a ohm meter the continuity of the ground cable and starter cables? Also, there are fuseable links in the circuit. Do you have a wire schematic?

rarebmx

iTrader: (6)

I have not tested cables nor the fuseable links. That is next step on my list. I believe there are four links?

red rock

iTrader: (2)

This isn't too good of an image, but may help some. Just a thought, but have you checked your fuses? http://videojourneysrentals.com/1989...ontrol-module/

red rock

iTrader: (2)

I was just searching around and found this; https://www.autozone.com/repairinfo/...96b43f80386616

antares57

iTrader: (8)

I gave up on this long ago on my '88 Firebird. My '91s don't do this. Swapped the starter, ignition switch,battery cables, etc. Read somewhere that it's in the resistance from the wire at the ignition switch to the starter. Rigged a permanent push button switch to bypass wiring. When it doesn't start properly, I use the button...works every time.

B1CrwDwg

yes, there was no ground from the starter just mating surface...mine is starting to act up again so thinking of running a secondary grofrom mating surface to a frame ground.

B1CrwDwg

THATS GOOD STUFF!!! Thanks

rarebmx

iTrader: (6)

Update on my 1989 IROC.....Ignition was bad. All swapped & running great again.