Just because I need to know as well....

All other VAT bypasses suggest using a resistor soldered inplace of the resistor found in the key.

What if you dont have the key???? The schematics suggest that the VATS is matched to the key, so it makes sense that you could bypass the entire box.

If you pull the vats box out from behind the dash, there are a limited number of wires going to it. Mainly, starter disable and ecm/fuel disable.

Bypass Starter disable -

Connect pin A3 to B1. Simple.

ECM/fuel disable -

???? Is this just a ground, as the schematics suggest? Or is this a pulsed signal to the ECM? I'm having troubles integrating an 89 VATS with a 92 ECM, so I assume something is going on here. Any suggestions? I've tried just grounding the pins to the ECM, but it doesn't help. It would be awesome to get this well documented.

 

When you think about pulling the VATS control module from behind the dash and jumpering wires, consider this. The computer chip in the ECM is programmed to look for a signal from this box. No signal, ECM no workee.

 

I've heard that the VATS sends a 40Hz square wave back to the ECM to enable proper starting/operating of the engine. I've not verified this myself (would be easy with a 'scope), but if it is the case, you could grab a 555 from RadioShack and a few resistors/caps and bypass it in that manner.

 

In the chiltons book, it does show a square wave next to that pin on the vats. I'll look into it. Have you heard of a maf or sd being different? I'm going to have troubles finding a 92 camaro around where I am. But I can definetly check the 89 MAF VATS.

 

I've no idea, but one way to check would be to call a dealer and get the part number for the VATS module for both engines and see if it's the same part number.

 

Good idea. It just so happens I know a hottie in the parts department at the chevy dealership. Hehe. Brb.

 

I can answer the part # question for you, the part numbers are the same from 1988 (Pontiac used on high end models) up through 1993 and the early part of 1994 in both the camaros and firebirds. This also applies to any other GM models that used the system with the pellet in the key. The part number for the VATS control module is #16135270. Please also note that GM has changed this part number over the years at least 5 times, however it will still cross over in their computers to the new number.

 

Then here's another question.

Does the VATS put out the same frequency, regardless of key resistance, or does it change? In other words, does the key match the ECM or the VATS?

If the part number is always the same for the VATS, then it would appear that the VATS puts out a frequency dependant of the key resistance. So in order to bypass it, I would have to use a 555 as suggested before. Or I could just find the right key resistance and solder it in like everyone else..... but where would be the fun in that?

 

Yes the VATS puts out the same frequency regardless of the resistance value in the key. The VATS control module looks for the resistance value that is burned into its memory, once it sees the correct value it seens a signal to the chip in the ECM. The ECM then allows the fuel injectors and starter to function. BTW, the resistance value cannot be changed in the VATS control module on our cars like they can in some other manufacturers cars. Once it is set there is no changing it.

 

If that is the case, then there should be 15 different VATS part numbers, one for every key resistance. But there seems to be only one part number.....

 

Got into this a while back. There are bypass modules using the transistor, buy on Ebay for about $40. The replacement VATS module from GM is open when new, will work with any resistance one time then it remembers that. From what I read no key pellet is needed for the new module to work. There are 15 or so resistance pellets used, might get a list and start trying them, get resistors at Radio Shack cheap. I went to the local dealer, ran the VIN, and got a key made with the correct resistance, cost $25 for one key.

 

You can:

1.) Get the eBay box for $40
2.) Grab assorted resistors from RadioShack for $5 and trial n error it
3.) Make your own square wave box for $15
4.) Buy the equipment to burn your own PROMS to delete the VATS depedency for $180
5.) See if someone on here can burn a stock PROM for you with VATS deleted for (hopefully) the cost of the chip.
6.) Have a dealer look up the original resistance to assist with #2, above.

#2 is the least expensive and probably the quickest way, but most likely very aggrevating...

 

I am reading this as I'm swapping an 87 GTA 5.7 into my Monte carlo. I'm trying to gather all the stuff I'm going to need to drop this motor and and run it. Now my cousin is a gm mechanic for like 30 years, so He'll be pretty good at rewiring this baby. My question is because this just came to my attention, that my ecm has a vats system programmed into (pretty sure its 87 and In 87 only trans ams(I think this includes gtas) and corvettes had them.

Can I buy an ECM for an iroc with a 5.7 in 1987 which has no vats systemand put that in place of the gta ecm?

Chevythunder.com will burn you a chip to bypass the the vats system. Check that out. $50 it quotes. You have to search the site however. I will look for you.

 

I'm fairly certain that all thirdgen engines had the VATS enable/disable set as a flag in the PROM -- which means all you need is the proper chip and you're set.

 

www.tpiparts.net flashed my stock chip- bypassing my VATS for $20.

 

The 87 models did not have the VATS in them. Pontiac started putting it in their high end models in 1988. Chevrolet didn't start with them until 1989 with the exception of the corvettes.

 

I was going by chevythunder's website. Its a tpi swap website. See http://www.chevythunder.com/fuel%20i....%20pg%20A.htm

Go down tot he second chart. 1986-1988
"Trans Am's and Corvettes ecm's have VATS programmed into prom"

Just my 2 cents.

 

By the way tpiparts.net only burns proms for speed density. Thats what the webpage says anyways. If anyone knows of a site that will bypass a vats system in a MAF ecm let me know

 

Yes I have read that and irregardless of what it says, there was not a VATS system in the trans-ams until 1988 and even then it was not in all models of it. That line about it was just a generalization of the systems for those years.
It is just like their comment about the intakes for 87 models fitting other models. This is true they will fit, however they are only good if you are using them with a system that has the cold start injectors unless you do a modification to them.

 

Kinda like microwave oven manufacturers telling everyone they cannot microwave metal. You can microwave some metal if you know how to do it correctly, but it's easier to make a generalized statement that it's ALWAYS BAD!!!.

 

In case the resistance values are of any use, I have them listed on my site...

http://tpiparts.net/vehicle_anti_theft_system__vats_/

Trickster is correct, VATS was implemented in the TransAms part way during the 1988 production run. Not all 88 TAs have it.

president89, you don't have anything to worry about. If its an 87, there is no VATS.

You are correct about the prom burning though. At the moment, we only have an option on the site to work on 90-92 proms. However, I've been meaning to put in an option for 86-89 proms, I just haven't had a chance. I will be doing so shortly.

 

how would you wire up the 555 to disable the vats system
thanks

 

You would need to know what the proper waveform was to feed to the ECM. I *believe* it is a 40Hz square wave. Someone would need to corroborate this before going any further, though.

 

Baker Electronic has a product that will bypass the vats for 24.95 . Has anyone ever used this product. It is shown on ebay and dealer site.
GM VATS or PASSkey II Bypass Module For LS1 and LT1
http://myworld.ebay.com/ebaymotors/bakerelectronic/

 

If you dont have a key to measure the resistance take the car to a GM dealer and they can use a intaragator to tell you what key(resistance) you need. Then buy the corisponding resistor from radio shack.

 

i went to ACE hardware cause they can cut VATS keys to find the resistance of my key to bypass the lock cyl. and they told me it was number ????soooooo i went and searched all over this is what i came up with

1 = no longer used = 392
2 = CN = 523
3 = FW = 681
4 = GP = 887
5 = KA = 1130
6 = N5 = 1470
7 = UN = 1870
8 = XB = 2370
9 = GA = 3010
10 = NP = 3740
11 = FY = 4750
12 = C5 = 6040
13 = XY = 7500
14 = KB = 9530
15 = UW = 11800

1 ...402(386-438)
2 ...523(502-564)
3 ...681(650-728)
4 ...887(850-942)
5 ...1130(1085-1195)
6 ...1470(1411-1549)
7 ...1870(1795-1965)
8 ...2370(2275-2485)
9 ...3010(2890-3150)
10 ...3740(3590-3910)
11 ...4750(4650-4960)
12 ...6040(5798-6302)
13 ...7500(7200-7820)
14 ...9530(9149-9931)
15 ...11800(11328-12292)
those are the acceptable ranges that each will take