Vats?
Thread Starter
Instructor
Joined: Oct 2007
Posts: 188
Likes: 3
Vats?
I have an 87
It has VATS key #13 7K ohms and there is an aftermarket jumper resistor in the car. The car runs fine most of the time, but sometimes it will not start. All other electrical is working BUT the injectors are not on. It stays this way for a while (sometimes hours) and then Vrrrrooom Starts right up. This is a problem.
I know it is not the key, the lock or the bypass resistor. Is it the VATS module? I replaced the starter relay. The car is 21 years old - I am not worried about somebody taking the car. I want the thing to start reliably, and 100%. How can I disable VATS???
It has VATS key #13 7K ohms and there is an aftermarket jumper resistor in the car. The car runs fine most of the time, but sometimes it will not start. All other electrical is working BUT the injectors are not on. It stays this way for a while (sometimes hours) and then Vrrrrooom Starts right up. This is a problem.
I know it is not the key, the lock or the bypass resistor. Is it the VATS module? I replaced the starter relay. The car is 21 years old - I am not worried about somebody taking the car. I want the thing to start reliably, and 100%. How can I disable VATS???
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
What do you mean by not starting? Does the starter motor not crank, or does the starter crank but the engine won't start and run?
If there is a resistor across the 2 pins on the wiring harness socket, then VATS is bypassed. If it cranks but the injectors aren't pulsed, then the VATS module could be at fault as it sends a square wave to the ECM to signal pulsing the injectors. Also check the two INJ fuses and fuse clips for being clean. I would also unplug the ECM and plug it back in to clean the connector contacts. See if you also have spark when it won't start. No spark also signifies that the ECM is not getting distributor pulses and therefore no injector pulses will occur either.
If there is a resistor across the 2 pins on the wiring harness socket, then VATS is bypassed. If it cranks but the injectors aren't pulsed, then the VATS module could be at fault as it sends a square wave to the ECM to signal pulsing the injectors. Also check the two INJ fuses and fuse clips for being clean. I would also unplug the ECM and plug it back in to clean the connector contacts. See if you also have spark when it won't start. No spark also signifies that the ECM is not getting distributor pulses and therefore no injector pulses will occur either.
Thread Starter
Instructor
Joined: Oct 2007
Posts: 188
Likes: 3
VATS and Qs about a VATSectomy
By "Won't start" I mean will not crank. If it was only the starter, I should be able to roll start it, or jump the starter. I can not roll start it (injectors are off), and I can directly jump to starter (power to the starter - and it works.
I pulled all the fuses - they are good. I changed the starter relay - it is good. It has a new computer in the car. I think it is the VATS decoder or reader module. The car always starts, after some time. It could take a number of tries, an hour, 4 hours, a day. Yesterday it took 2 hours.
I know it is VATS because of the pair - starter and injectors - I just want to get rid of it, too much hassle. It is not preventing theft, it is preventing use.
How can I do a VATSectomy
I pulled all the fuses - they are good. I changed the starter relay - it is good. It has a new computer in the car. I think it is the VATS decoder or reader module. The car always starts, after some time. It could take a number of tries, an hour, 4 hours, a day. Yesterday it took 2 hours.
I know it is VATS because of the pair - starter and injectors - I just want to get rid of it, too much hassle. It is not preventing theft, it is preventing use.
How can I do a VATSectomy
Burning Brakes
Joined: Nov 2006
Posts: 763
Likes: 2
From: Weston FL
By "Won't start" I mean will not crank. If it was only the starter, I should be able to roll start it, or jump the starter. I can not roll start it (injectors are off), and I can directly jump to starter (power to the starter - and it works.
I pulled all the fuses - they are good. I changed the starter relay - it is good. It has a new computer in the car. I think it is the VATS decoder or reader module. The car always starts, after some time. It could take a number of tries, an hour, 4 hours, a day. Yesterday it took 2 hours.
I know it is VATS because of the pair - starter and injectors - I just want to get rid of it, too much hassle. It is not preventing theft, it is preventing use.
How can I do a VATSectomy
I pulled all the fuses - they are good. I changed the starter relay - it is good. It has a new computer in the car. I think it is the VATS decoder or reader module. The car always starts, after some time. It could take a number of tries, an hour, 4 hours, a day. Yesterday it took 2 hours.
I know it is VATS because of the pair - starter and injectors - I just want to get rid of it, too much hassle. It is not preventing theft, it is preventing use.
How can I do a VATSectomy
Here's some links to the various posts/threads I've had regarding this issue. There's some good info in there (there's also a lot of BS). Most important is the link to the VatsSucks web site.
Good luck.
http://forums.corvetteforum.com/show....php?t=1807019
http://forums.corvetteforum.com/show....php?t=1759701
http://forums.corvetteforum.com/show...867&highlight=
http://forums.corvetteforum.com/show...813&highlight=
http://forums.corvetteforum.com/show...615&highlight=
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Your VATS is bypassed and it won't crank. Here are what can cause that: Poor battery cable connection, clutch safety switch defective (gear selector sw if automatic), defective start enable relay, defective starter solenoid or contacts inside the starter motor, defective starter motor. Injectors and spark require the engine to be turning, so if you can't crank, don't expect injectors pulsing or spark. One symptom of poor battery connection, dashlights go out in crank position. Bad starter contacts (pulled together by the starter solenoid), you hear the starter solenoid click, dashlights stay on but no cranking.
Also, don't roll start your car or you will be repairing the OD, I know by experience!
I suggest you unplug the clutch safety switch and put a jumper across the socket and try a crank. There must be 12v on the jumper with the ign sw in crank position, if not, then the start enable relay is not closed, or start contact on the ign sw is defective. Also, check the quality of the bypass resistor connection on the 2 pin connector on the wiring harness. Measure the resistance of the bypass resistor (disconnected), it must be within 4% of 7500 ohms. The limits of the resistance is 7200 to 7820 ohms.
Also, don't roll start your car or you will be repairing the OD, I know by experience!
I suggest you unplug the clutch safety switch and put a jumper across the socket and try a crank. There must be 12v on the jumper with the ign sw in crank position, if not, then the start enable relay is not closed, or start contact on the ign sw is defective. Also, check the quality of the bypass resistor connection on the 2 pin connector on the wiring harness. Measure the resistance of the bypass resistor (disconnected), it must be within 4% of 7500 ohms. The limits of the resistance is 7200 to 7820 ohms.
Last edited by jfb; Oct 12, 2008 at 12:06 PM.
Instructor
Joined: Oct 2008
Posts: 163
Likes: 0
From: Gulf State
newbees info
Frank, i am having similar problem with my 88. I bought ingintion by pass. that just makes the vats think the correct ressistor is in the key. You can get rid of vats by going to pcmforless.com and purchase the vats chip. This supposedly takes the vats out of the car altoghther. I bought it thinking my problem was the vats but I still have the problem. Assuming i recieved the correct part form PCM for less. I guess now I must have starter relay or some other electrical problem. I am asking the forum for thier opinion. good luck and let me know what you find.
