VATS Question for 1992
Thread Starter
Intermediate
Joined: Mar 2001
Posts: 34
Likes: 0
From: Myrtle Beach SC
VATS Question for 1992
My 92 sometimes won't start. Turn the key over it will start then shut off. The system light flashes on the dash. This happens over and over then out of the blue it will start and run ok. While driving the system light still blinks. Lately in the middle of the night when it gets cold out the horn will start blowing. I'll unlock the driver door and relock it and it stops. I've been unhocking the battery so I don't have to get up at night.
Does anybody have a quick way to fix this or is there anyway to unhook the VATS system?
Thanks
Does anybody have a quick way to fix this or is there anyway to unhook the VATS system?
Thanks
Melting Slicks
Joined: Mar 1999
Posts: 2,830
Likes: 20
From: Las Vegas Nevada
Don't take this as gospel but I'm pretty sure the VATS system is seperate from the regular security system in the car. At least it was on earlier models (which I'm more familiar with).
Later (early 90) GM did away with the VATS module and incorporated it in the Body Control Module. I am pretty sure this module controls the security system as well. May be your BCM is on the fritz.
Someone with more knowledge specific to 90's vettes can chime in on this.
Later (early 90) GM did away with the VATS module and incorporated it in the Body Control Module. I am pretty sure this module controls the security system as well. May be your BCM is on the fritz.
Someone with more knowledge specific to 90's vettes can chime in on this.
Pro
Joined: Oct 2005
Posts: 557
Likes: 1
From: Ottawa Ontario
Heres a collection of vats stuff to help you.
1.VATS measures the resistance of the pellet in your ign key. If it doesn't agree within 5% of the value it will not close the start enable relay and your starter will not crank. It also tells the ECM to not exercise the injectors so the car cannot be push started. The ECM upon determining that the VATS disallowed a crank, will not a crank for 6 minutes.
Most likely your pellet contacts are worn, or the contacts in the ignition switch tumbler are no longer making reliable connection to the pellet. Also, there is a clutch safety switch which forces you to depress the clutch in order for the starter to work (gear selector switch if automatic). The next time you can't crank, jump the clutch safety switch and measure the voltage on the jumper. The voltage should be 12v with the ign sw in crank position. If not, then VATS isn't closing the start enable relay. You can check the ign tumbler contacts by removing the hush panel above the driver's feet and find the two wires from behind the steering column going to a 2 pin connector. Unplug the connector, insert your ign key and measure the resistance across the wires from the steering column. It should measure the same as your pellet. If over 13k ohms, you need a new ign tumbler or key. You can temporarily bypass VATS by clipping a fixed resistor across the 2 wires going into the wiring harness (goes to the VATS module) the same value as your pellet. You can use a 1/4 watt 5% resistor from Radio Shack. Don't permanently bypass VATS because 99% of thefts are done by bashing the column and jumping the ignition.
2.I'm going to wire in a bypass and switch to cure my intermittant VATS problems. Before I go cutting things, I want to make sure I'm working with the right wires.I traced out the wiring to a set of VERY skinny black wires under the steering column which connects to another set of larger black and white wires.Are these the ones I need to be working with?
Yes..the vats wires are very skinny, but there is a pair of them, white in colour, housed in an orange outer. They connect, via a small black plug, to a brown and yellow wire that go directly to the vats module.
The other extremely skinny wires, housed in a black outer, are cruise control wires...! These have a blade-like connector at the end..
IMO you are better off cutting the brown and yellow wires to fit a resistor or by-pass, as they are heavier and easier to work with.
As long as your cont test comes out from the lock column, then it's most likely the correct wires. I think mine were yellow and some other color, i don't recall. Its dark under the dash. It's pretty obvious though. Sitting in the drivers seat, the wires came out of the dash, then ran up right-of-center from the bottom of the steering column up to the lock cylinder.
3. we clipped the wires after the connector (between the lock and the connector) and then I just unhooked the connector and brought it inside.
We then measure the OHMs of the key, and I had bought a large pack of resistors at RadioTrash and we found 3 that gave it the correct OHM reading. We soldered them together and then soldered them to the clipped wires. Now what I had was a connector with 2 wires, and 3 resistors soldered between them which I covered with heat shrink.
I then just went back out to the car, plugged in the connector and the car fired right up with NO problems!! this was after a year of sitting in the driveway scratching my head as to how to make it start... all it took was 3 resistors costing me $.06 total!!the whole project took roughly 15-20 mins to do.
Vats Q and A
VATS can keep your vette from being stolen. 99% of thefts are done by bashing the column and jumping the ignition. The person I bought my 87 from had a 90 and came out of work to broken glass and a bashed column, but the vette hadn't moved an inch. Keep your car in good repair !!!
The VATS module closes the start enable relay and tells the ECM to exercise the injectors by comparing the pellet resistance with the stored number. If the resistance isn't correct, then VATS makes you wait 6 minutes to try again. The starter solenoid gets power through the ign sw crank contact, the start enable relay, and then the clutch safety switch (gear selector switch if automatic). First try your spare ign key as its pellet contacts aren't worn like your everyday key. Next, jump the clutch safety switch and try a crank while measuring the voltage on the jumper. If you don't have 12v on the jumper in crank position, then you will have to determine where the circuit is not continuous. You can test the starter by jumping 12v to the clutch safety switch jumper, the starter should run. Most VATS troubles are due to worn contacts in the ign tumbler that make connection to the pellet. You can check this out by removing the hush panel above the drivers feet and finding the 2 wires from behind the steering column that go to a 2 pin connector. Unplug the connector, insert ign key and measure the resistance across the wires from the column. It should measure the same as the pellet. If over 13k ohms, you need a new ign tumbler which has new contacts that touch the pellet. You can temporarily bypass VATS by connecting a fixed resistor the same value as your pellet across the 2 wires that go into the harness (these go to the VATS module). You can use 1/4 watt 5% resistor from Radio Shack. There is no need to spend $30 for a bypass kit.
1.VATS measures the resistance of the pellet in your ign key. If it doesn't agree within 5% of the value it will not close the start enable relay and your starter will not crank. It also tells the ECM to not exercise the injectors so the car cannot be push started. The ECM upon determining that the VATS disallowed a crank, will not a crank for 6 minutes.
Most likely your pellet contacts are worn, or the contacts in the ignition switch tumbler are no longer making reliable connection to the pellet. Also, there is a clutch safety switch which forces you to depress the clutch in order for the starter to work (gear selector switch if automatic). The next time you can't crank, jump the clutch safety switch and measure the voltage on the jumper. The voltage should be 12v with the ign sw in crank position. If not, then VATS isn't closing the start enable relay. You can check the ign tumbler contacts by removing the hush panel above the driver's feet and find the two wires from behind the steering column going to a 2 pin connector. Unplug the connector, insert your ign key and measure the resistance across the wires from the steering column. It should measure the same as your pellet. If over 13k ohms, you need a new ign tumbler or key. You can temporarily bypass VATS by clipping a fixed resistor across the 2 wires going into the wiring harness (goes to the VATS module) the same value as your pellet. You can use a 1/4 watt 5% resistor from Radio Shack. Don't permanently bypass VATS because 99% of thefts are done by bashing the column and jumping the ignition.
2.I'm going to wire in a bypass and switch to cure my intermittant VATS problems. Before I go cutting things, I want to make sure I'm working with the right wires.I traced out the wiring to a set of VERY skinny black wires under the steering column which connects to another set of larger black and white wires.Are these the ones I need to be working with?
Yes..the vats wires are very skinny, but there is a pair of them, white in colour, housed in an orange outer. They connect, via a small black plug, to a brown and yellow wire that go directly to the vats module.
The other extremely skinny wires, housed in a black outer, are cruise control wires...! These have a blade-like connector at the end..
IMO you are better off cutting the brown and yellow wires to fit a resistor or by-pass, as they are heavier and easier to work with.
As long as your cont test comes out from the lock column, then it's most likely the correct wires. I think mine were yellow and some other color, i don't recall. Its dark under the dash. It's pretty obvious though. Sitting in the drivers seat, the wires came out of the dash, then ran up right-of-center from the bottom of the steering column up to the lock cylinder.
3. we clipped the wires after the connector (between the lock and the connector) and then I just unhooked the connector and brought it inside.
We then measure the OHMs of the key, and I had bought a large pack of resistors at RadioTrash and we found 3 that gave it the correct OHM reading. We soldered them together and then soldered them to the clipped wires. Now what I had was a connector with 2 wires, and 3 resistors soldered between them which I covered with heat shrink.
I then just went back out to the car, plugged in the connector and the car fired right up with NO problems!! this was after a year of sitting in the driveway scratching my head as to how to make it start... all it took was 3 resistors costing me $.06 total!!the whole project took roughly 15-20 mins to do.
Vats Q and A
VATS can keep your vette from being stolen. 99% of thefts are done by bashing the column and jumping the ignition. The person I bought my 87 from had a 90 and came out of work to broken glass and a bashed column, but the vette hadn't moved an inch. Keep your car in good repair !!!
The VATS module closes the start enable relay and tells the ECM to exercise the injectors by comparing the pellet resistance with the stored number. If the resistance isn't correct, then VATS makes you wait 6 minutes to try again. The starter solenoid gets power through the ign sw crank contact, the start enable relay, and then the clutch safety switch (gear selector switch if automatic). First try your spare ign key as its pellet contacts aren't worn like your everyday key. Next, jump the clutch safety switch and try a crank while measuring the voltage on the jumper. If you don't have 12v on the jumper in crank position, then you will have to determine where the circuit is not continuous. You can test the starter by jumping 12v to the clutch safety switch jumper, the starter should run. Most VATS troubles are due to worn contacts in the ign tumbler that make connection to the pellet. You can check this out by removing the hush panel above the drivers feet and finding the 2 wires from behind the steering column that go to a 2 pin connector. Unplug the connector, insert ign key and measure the resistance across the wires from the column. It should measure the same as the pellet. If over 13k ohms, you need a new ign tumbler which has new contacts that touch the pellet. You can temporarily bypass VATS by connecting a fixed resistor the same value as your pellet across the 2 wires that go into the harness (these go to the VATS module). You can use 1/4 watt 5% resistor from Radio Shack. There is no need to spend $30 for a bypass kit.
Melting Slicks
Joined: Mar 1999
Posts: 2,830
Likes: 20
From: Las Vegas Nevada
Great post Canam. Normally the first thing I would have recommended would be clean the pellet, but he mentioned that the security system goes off for no reason in the middle of the night.
Doesn't the BCM control this? If so and it's going off for no reason it may need service/replacment. I also believe that in later years VATS was moved to the BCM. This coupled with his other problem is why I thought the BCM could be the problem.
Of course I am only speculating as I don't have first hand knowledge of later C4's.
Doesn't the BCM control this? If so and it's going off for no reason it may need service/replacment. I also believe that in later years VATS was moved to the BCM. This coupled with his other problem is why I thought the BCM could be the problem.
Of course I am only speculating as I don't have first hand knowledge of later C4's.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
good post..
Remeber that there are 2 parts of the VATS system. 1 is a starter interrupt and can be bypassed with a jumper across the relay and the second is a fuel cut in the stock PCM/ECM The fuel cut can be removed with a chip.
Remeber that there are 2 parts of the VATS system. 1 is a starter interrupt and can be bypassed with a jumper across the relay and the second is a fuel cut in the stock PCM/ECM The fuel cut can be removed with a chip.
Thread Starter
Intermediate
Joined: Mar 2001
Posts: 34
Likes: 0
From: Myrtle Beach SC
Thank for the help but???
I put the resister in and it still does the asme thing.
It starts and shuts off again. Sometimes it will run ok then the next time you start it shuts off right away. A friend checked the chip in the key and checked the key switch and said it is making contact ok and he doesn't think the problem is with the chip, key or switch. Any other suggestions.
Thanks Joe
It starts and shuts off again. Sometimes it will run ok then the next time you start it shuts off right away. A friend checked the chip in the key and checked the key switch and said it is making contact ok and he doesn't think the problem is with the chip, key or switch. Any other suggestions.
Thanks Joe
