VATS Bypass Tutorial with Pics

[LT4man]

CCM stands for Central Control Module.

SAVE THE

 

[TedC]

I found this...
1990-94 LT1 system uses a more sophisticated VATS system to disable the injectors. The resistance is read by a VATS module (Camaro, Firebird and Trans AM) or a Command Control Module (CCM) for the Corvette. If the key is the right resistance a signal is sent to the ECM enabling the injector circuit. If the sequence or the resistance is not correct,the engine will not start. This answers why you can't find the VATS module in your service manual. Now you need to research how the CCM signals the starter relay to engage and verify this is actually happening.

 

[Surfin' Elvis]

Thanks TedC, at least no I am not looking for a VATS module anymore!!
I will look for references to this issue in the service manual tomorrow.
God I hope I don't have to replace that CCM. It's way back in the dash!

 

[Bestdavidd]

My VATS drove me crazy too long...I beat it on my own terms! First go to TBI power chips and get a reflashed memcal prom, Deleting the VATS program (cost about $75.00) this does away with the fuel pump and injector pulse problem. Then drop the driver column cover and find the relay with the large yellow wire and the large purple wire, cut them at the relay and butt connect the two of them together. That takes care of the starter interrupter relay problem! Then throw away the remote control and lock your doors when you want! CAVEMAN STYLE....

hello! i want to know how can do to alow the fuel pump and inyectors, because my car cranks but no start, and tells me the ``41 code´´, im sick of it, my car has 1 month that does not start and im sick...

 

[Blake Sanders]

vats by-pass

will this work for lost keys? if no then what can be done? i've already installed new lock cylinder but it came with non resistor key.

 

[Blake Sanders]

lost keys

Yes but you need to know the resistance of your old key resistor pellet so you can install the correct value resistors into the VATS wiring


Get a new key cut with the correct resistor pellet to suit your new lock barrel ; blank GM keys are available; with the 15 different resistors
GM VATS Key Blank Single Sided Cadillac Chevy Ponitac | eBay

all you need to know is which # key you need
Read
VATS and PASSKey Vehicle Anti-Theft Systems - ThirdGen.org

Some locksmiths can read the old key for you ( and have the new blank keys ) , otherwise you will have to measure it yourself with a DVM

thats just it, i don't have the key, they are missing, have been for weeks. their where abouts are unknown. at $30 some odd dollars a key i can't afford to roll the dice and hope i get lucky by the 4th or 5th key. can vats be totally removed from the equation?

 

[Blake Sanders]

lost keys

Options
Get VATS deleted on the tune
VATS Delete Chips

Or buy a signal generator for the fuel enable signal required by the ECM
Baker Electronix - GM VATS Bypass

Either of above require manually bypassing ( or deleting of ) the starter enable relay.
VATS gone for good

.....................
Fitting the resistors keeps VATS intact , just fools it into thinking the correct key is in the Ign
Makes the system useless as a security device and still leaves the VATS module and starter relay as future fail points
Requires you to make up and try the 15 resistor combinations until you get correct one for your car

an easier way i just figured out this afternoon is using a variable pot. i found one that covers the first four combinations. i just soldered it to the original cylinder plug, sounds easy enough, yeah right. i'm trying it tommarrow. wish me luck.

 

[bubbaextra]

contact info for speedmaster4

I am looking for the parts list and schematic that you describe.
Thanks
Bubbaextra

ecm outputs +5v and must see this output ''grounded'' at 30 hz (continuous ground will not work) before the ecm will ''pulse'' the fuel injectors...you can eliminate the ign key resistor, vats module, assoc wiring by sinking (grounding) the ecm output (86-89 ecm pin B6, white wire, other years vary) into a simple 30 hZ gen.

i used the ''venerable'' 555 ic chip with resistors, capacitors to do it (plus a transistor to sink, as the 555 supposedly can sink directly but i haven't figured that out yet)and diodes to assure no backfeed/damage to the ecm...my concoction has three wires leaving it, which tie into existing wires at the ecm for +12v/ground/ vats +5v output.

was into solid state design long ago, still newb with internet, can't scan /post the schematic...last time i said ''freebie'' on the net i got 2000+ requests, never again(you do the math)...for a minimal donation (very minimal,whatever you think correct, i have no desire to make a profit and then need to deal with the feds re taxes) to cover gas/photocopy/ mailing i will be happy to send you the schematic/raddyshack parts list to do with as you please --post here, mfg,etc.

there was an on-line vendor (still ?) that sold the device, apparently also 555 based, but in a plastic housing with a red LED (oh wow) for abt $50, if you're not into making a little solder smoke...i can't recommend them as i never bought one,tho.

btw, you can check if the ecm/ vats output is properly conditioned by checking voltage on that wire from ecm pin B6 with a digital VOM, abt +2.5 volts means go, 0 or +5v will result in a ''no injector signal'' at the ecm/injector pins.

 

[dlfisher1972]

I know this is a very OLD post, but I use this forum a lot to look up issues with my 1989 C4 Coupe, Automatic transmission 110K miles. I fall into the #4 category you listed above. Currently I believe I am suffering to the VATS system, I have tried everything else and this cheap fix will be a good thing if works for me. I turn the key and while everything works, the car does not crank nor attempt to crank. I hear the fuel rail prime and all, but turing the key does nothing otherwise.
My question though is that when purchasing my resistor/resistors, I am seeing a WATT reference. I was looking at FRY's and see 1-WATT or 2-WATT references. My goal is 898 Ohm, and found the combination of 4.7k with a parallel inline combination of 1000 ohm and 100 ohm, gets me to 891 ohms. Which I believe is close enough to the range I need. But the WATT reference concerns me...What should I be looking at for this? (There are no more RadioShacks to go grab this stuff from anymore, so Fry's is my only and closest option)...
Thanks to everyone that has contributed here...you guys are a lifesaver! More than I can even say.