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Old 10-16-2011, 09:35 AM
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1986 vette

can some one tell me how to by pass the vatts system on my 1986 vette it has 5.7 eng 700 r 4 trans tune port injection
starts runs about 3 seconds then dies will restart same result

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Last edited by stickchewy21; 10-16-2011 at 09:54 AM. Reason: to give more info
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Old 10-16-2011, 10:15 AM
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You need to know what resistance the BCM expects to see from the key. Using resistors and a potentiometer(not needed if using high quality resistor) in parallel you can achieve this resistance. Then all you do is splice the resistor(s) in place of the VATS unit on the steeering column; two black wires. Just remember if you do this the car is 100 times easier to steal.

IMO bypassing the VATS is a bad idea. I would just fix the system; it is not that hard or expensive. It could be a key, halo in column, or a wiring issue to the BCM.

Good Luck.
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Old 10-16-2011, 10:57 AM
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vatts 1986 vette

i used a key programing unit from a lock smith to test the vatts system i can erase the memory and reprogram the key still starts and dies in about 3 seconds will installing the resistors on the sterring column help this matter
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Old 10-16-2011, 02:12 PM
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The VATS system module activates a relay called STARTER ENABLE RELAY. That means that the engine won't crank unless the VATS systems is working.
Most likely the fuel pump is not running after the initial 3 second prime period.
This prime period is controlled by the ECM through a relay called the FUEL PUMP RELAY.
After the prime period expires the cranking or running engine will have attained sufficient oil pressure to activate an OIL PRESSURE SWITCH. This OPS then creates a circuit the supply power to the fuel pump.
Check to see if the OPS is closing when the engine is cranking. Connect a test light to the FUEL PUMP FUSE to determine if the fuel pump power is maintained during cranking, running. Most likely the OPS is not working or the engine oil pressure is to low to activate it.

vicrod
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Old 10-16-2011, 02:28 PM
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Must be he didnt like these answers, he posted the same question again.
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Old 10-16-2011, 04:08 PM
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1986 vette

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Originally Posted by latech
Must be he didnt like these answers, he posted the same question again.
sorry just new at the forum and how to nav threw it thanks i will check thoes things out
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Old 10-16-2011, 05:03 PM
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vatts on the vette

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Originally Posted by vicrod
The VATS system module activates a relay called STARTER ENABLE RELAY. That means that the engine won't crank unless the VATS systems is working.
Most likely the fuel pump is not running after the initial 3 second prime period.
This prime period is controlled by the ECM through a relay called the FUEL PUMP RELAY.
After the prime period expires the cranking or running engine will have attained sufficient oil pressure to activate an OIL PRESSURE SWITCH. This OPS then creates a circuit the supply power to the fuel pump.
Check to see if the OPS is closing when the engine is cranking. Connect a test light to the FUEL PUMP FUSE to determine if the fuel pump power is maintained during cranking, running. Most likely the OPS is not working or the engine oil pressure is to low to activate it.

vicrod
thanks for taking time to explain this info i will check it out and let you know what i come up with again thanks
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Old 10-16-2011, 07:58 PM
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Hope it works out.

vicrod
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Old 10-17-2011, 12:58 AM
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I think Vicrod is probably right, the car will not start at all if the vats parameters are not met. It's not hard to bypass but what led you to believe that this is the problem? I believe you can temporarily bypass the ops by running 12v to the fuel pump relay terminal that the oil pressure switch feeds. If I remember correctly, the ops switch is on the back of the block, below the base of the distributor.
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Old 10-17-2011, 03:59 AM
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THe fuel pump relay has 12v to it...... all you have to do is pull the relay and put a jumper across the Comm and Normally open terminals........ this will bypass the safety features tho'
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Old 10-21-2011, 01:44 PM
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The VATS can also be deactivated in the ECM with a custom prom chip. You can either buy one, or order the tools to do it yourself and learn to burn you own chips. That's what I did on my 66 GMC when I installed a TPI from an early C4 Vette.
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