Need help on my 96Z28
11-15-2010, 07:02 PM
#1
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Need help on my 96Z28 I'm guessing this issues has something to do with security,but everytime I start the car it runs fine for about 5-6 seconds then dies,yesterday it wouldn't even start,I had a security light on and it wasn't activating the starter,so I grounded the yellow/black wire going to the theft relay and now it starts and then dies...I need to know what I could do at this point.Any help is appreciated.
11-16-2010, 08:19 AM
#5
It is your VATS system causing the problem. The VATS system prevents the car from starting in two ways - it disables the ground to the coil side of the starter relay and it disables the fuel enable signal to the PCM. So, even when you bypass the starter relay connection, your engine starves for fuel.
You options are to bypass VATS, buy a new BCM, or bypass the starter relay ground and have the PCM tuned to ignore the lack of fuel enable signal from the BCM.
You options are to bypass VATS, buy a new BCM, or bypass the starter relay ground and have the PCM tuned to ignore the lack of fuel enable signal from the BCM.
11-16-2010, 12:01 PM
#9
You can buy a VATS bypass module but it's not necessary if you have basic electronics skills (or know somebody who does). Simply measure the resistance across the pellet on your key and compare the value to one of the 15 valid values. You can find lots of lists of valid values by googling "VATS resistor values". Once you know the needed resistance, you can buy the necessary resistor(s) from Radio Shack for just a couple of bucks. Some wire, some solder, and some heatshrink tubing and you have your own VATS bypass.
11-16-2010, 12:41 PM
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I already tried the resistor approach.I have signal coming down the column to the plug for VATS so thats not the issue.I grounded the wire on the TDR and now it starts but shuts off after 5 seconds or so.
11-16-2010, 02:44 PM
#11
Okay, well a VATS bypass module doesn't do anything different from using your own resistors. All it does is provide resistor setups for all 15 possible values instead of just the one that matches your key. In other words, if the resistors didn't work, a VATS bypass module won't work either.
There's only two possible reasons that the resistors didn't work - they were incorrectly installed or the BCM is faulty.
There's only two possible reasons that the resistors didn't work - they were incorrectly installed or the BCM is faulty.
11-16-2010, 03:57 PM
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Went to the junkyard a few minutes ago and I found alot of camaro's out there,but they were all V6 models...with that being said,can I use a BCM out of it,I know that's probably a dumb question,but they look exactly the same and they have the same 3 connectors on it.I also went back over everything like key resistance to the VATS connector,battery terminals are clean and tight,good charge on battery.Keep in mind I initially couldn't even start the car until I grounded the yellow/black wire on the TDR...so what would have caused me to get no signal to the starter in the first place?I hope I figure this out soon.Bought the car with a blown engine and just put a new one in and i can't drive it yet.ahhhhh....this sucks
11-16-2010, 04:12 PM
#15
There is no VATS module - the VATS circuitry is in the BCM.
Went to the junkyard a few minutes ago and I found alot of camaro's out there,but they were all V6 models...with that being said,can I use a BCM out of it,I know that's probably a dumb question,but they look exactly the same and they have the same 3 connectors on it.I also went back over everything like key resistance to the VATS connector,battery terminals are clean and tight,good charge on battery.Keep in mind I initially couldn't even start the car until I grounded the yellow/black wire on the TDR...so what would have caused me to get no signal to the starter in the first place?I hope I figure this out soon.Bought the car with a blown engine and just put a new one in and i can't drive it yet.ahhhhh....this sucks
11-16-2010, 04:21 PM
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Ok I understand....only other thing I forgot to mention was that my passenger window won't go down,not sure if that's bcm related or not.What else would cause it to shut down like that?Something had to be causing me not to get signal to the starter in the first place,then I bypassed it.I'm not sure where to go from here.
11-17-2010, 07:36 AM
#17
Okay, let me try to explain this one more time...
1. Your security light is on and the car won't start. This means that the VATS system (in the BCM) is not recognizing the ignition key resistor pellet as being the correct value.
2. The VATS system prevents a car from starting in two ways... it disables the ground to the starter relay so the starter will not engage and it disables the fuel enable signal to the Powertrain Control Module (PCM) so that even if the engine cranks, there will be no fuel to keep it running.
3. You have bypassed the starter problem by providing a separate ground for the starter relay (independent of VATS in the BCM). The engine now cranks but still won't run because the fuel is shut off by VATS.
Your choices are to fix the VATS problem or bypass it. To fix it, you'll need to make sure that the contacts on the key are clean and not worn too much to make contact inside the ignition cylinder. You'll also have to make sure the contacts in the ignition cylinder are clean and not worn too much to prevent connection to the key pellet. Cleaning is easy but fixing worn contacts can be difficult and expensive.
To bypass VATS you can buy a VATS bypass module or you can build one yourself using inexpensive resistors. The other alternative is to bypass the starter relay ground as you've already done AND get your PCM programmed to ignore the lack of a fuel enable signal from the BCM. This will let you start the car but it won't get rid of the security light on the dash.
There is a very remote possibility that your BCM is bad but it is highly unlikely.
1. Your security light is on and the car won't start. This means that the VATS system (in the BCM) is not recognizing the ignition key resistor pellet as being the correct value.
2. The VATS system prevents a car from starting in two ways... it disables the ground to the starter relay so the starter will not engage and it disables the fuel enable signal to the Powertrain Control Module (PCM) so that even if the engine cranks, there will be no fuel to keep it running.
3. You have bypassed the starter problem by providing a separate ground for the starter relay (independent of VATS in the BCM). The engine now cranks but still won't run because the fuel is shut off by VATS.
Your choices are to fix the VATS problem or bypass it. To fix it, you'll need to make sure that the contacts on the key are clean and not worn too much to make contact inside the ignition cylinder. You'll also have to make sure the contacts in the ignition cylinder are clean and not worn too much to prevent connection to the key pellet. Cleaning is easy but fixing worn contacts can be difficult and expensive.
To bypass VATS you can buy a VATS bypass module or you can build one yourself using inexpensive resistors. The other alternative is to bypass the starter relay ground as you've already done AND get your PCM programmed to ignore the lack of a fuel enable signal from the BCM. This will let you start the car but it won't get rid of the security light on the dash.
There is a very remote possibility that your BCM is bad but it is highly unlikely.
11-17-2010, 10:06 AM
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ok...sorry bout that....I tried the resistors again a few minutes ago and now the light starts to flash instead of being steady lit up like it was.
11-17-2010, 10:40 AM
#19
When the security light is flashing, it means the BCM can't see a resistor at all - as though you used an old-style key that doesn't have the resistor pellet in it. Basically, you don't have your resistor connecting the two wires together so the BCM sees an open circuit.
11-17-2010, 11:01 AM
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ok i got ya...what I did was just unplug the vats connector and put the resistor in on the side going to the bcm.and just left the orange wires unplugged.i tried puttin the resistor in from the top of the connector but it went back steady,so i spliced the purple and white wires and just wrapped the resistors around the part where i spliced and it went to flashing.so,ill try again for a better connection