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VATS module location / access ... or how to test my spare VATS module ?
I got a couple spare used VATS modules with keys that I like to make sure do work if I ever need to use one of them. My car is a 1989 TTA
I got two options:
1. put one in the car and test it that way however question is where is the VATS module so I can pull the plug and plug in one of my spares?? I’ve been under the dash several time however never managed to see it.
2. bench test the VATS module, anyone got some experience doing so and can give me a few pointers?
Re: VATS module location / access ... or how to test my spare VATS module ?
I had VATS disabled with a new prom and jumpered the relay permanent, I didn’t want to take any chances.
The location of your VATS relay should be on driver side, you need to remove your hush panel for access and if you look up and toward your fender the relay should be mounted up there. Good way to identify it is it has 4 wires, 2 large and 2 small and I believe the large wires are yellow and green IIRC.
Note on some cars the module is located underneath this rubber sheet type thing that you can access by removing the driver side kick panel. Wires will be same color for identification.
Re: VATS module location / access ... or how to test my spare VATS module ?
Thanks for responding however I’m after the location of the actual module (larger grey box) and not the relay.
I know how to bypass it all but have no problem with my VATS system and keeping my TTA stock hence keeping spare parts handy just to swap them out if needed.
so it’s the actual module location and how to get to it rather than the easy to access relay.
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by jlarsson
Thanks for responding however I’m after the location of the actual module (larger grey box) and not the relay.
I know how to bypass it all but have no problem with my VATS system and keeping my TTA stock hence keeping spare parts handy just to swap them out if needed.
so it’s the actual module location and how to get to it rather than the easy to access relay.
Your not gonna like the answer .......
In order to keep the module safe from attempted car thieves , GM buried the VATS module about as deep into the dashboard as they possibly could . In these pictures I was replacing the interior of my car since a previous owner thought orange and green was a good color combo (I put all of the proper black & grey parts back in) . You can see the VATS module hanging from it's wires right in the area of the radio / HVAC controls . Since I wasn't after the VATS module specifically I'm not 100% sure how much of the dash has to come apart , but I do believe the dash piece in my second pic has to at least be unbolted and moved back somewhat in order to gain access to it because I think I remember the module being bolted to the back of it or perhaps to the HVAC ducting that's in the picture laying on the hood .......
Last edited by OrangeBird; 10-24-2020 at 07:55 AM.
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by OrangeBird
Your not gonna like the answer .......
In order to keep the module safe from attempted car thieves , GM buried the VATS module about as deep into the dashboard as they possibly could . In these pictures I was replacing the interior of my car since a previous owner thought orange and green was a good color combo (I put all of the proper black & grey parts back in) . You can see the VATS module hanging from it's wires right in the area of the radio / HVAC controls . Since I wasn't after the VATS module specifically I'm not 100% sure how much of the dash has to come apart , but I do believe the dash piece in my second pic has to at least be unbolted and moved back somewhat in order to gain access to it because I think I remember the module being bolted to the back of it or perhaps to the HVAC ducting that's in the picture laying on the hood .......
I was suspecting that was the case as I've been under my dash enough times over the years and never seen it .... thanks for sharing the picture that gives me a indication where to look / feel and see if I might be able to just unplug it (or not) without removing anything.
I did find this illustration and seems like it's either on the front or the back of the HVAC ducting :-(
Appreciate your sharing! If I can't get to it I will figure out a way to simply bench test it ... I got a spare complete dash harness in one of my many boxes so might hook up power to that one and see if the starter relay clicks or not, might be one option to be able to test my spare/s module.
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by scooter
That is the rear of the HVAC duct. You have to remove the dash to R&R it
I believe that is the front of the duct. By that year the module was between the duct and firewall. The easiest one I got from the recycle yard, the windshield had already been removed...
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by jlarsson
bummer ... bench testing it is then ... realised I got 3 spare used modules and one NOS
thanks all for your responses, much appreciated!
To set up for bench testing need the harness pigtail, a bulb or LED for the 'security' light, some resistors, P/S and time. As you try each resistor value need to wait 10 minutes with the power off before trying the next value. I know that the service manual states 4 or 5 minutes, but ten works better.
Also, if the NOS module has never been used it will remember the value of the first key used. They auto-program themselves.
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by RBob
To set up for bench testing need the harness pigtail, a bulb or LED for the 'security' light, some resistors, P/S and time. As you try each resistor value need to wait 10 minutes with the power off before trying the next value. I know that the service manual states 4 or 5 minutes, but ten works better.
Also, if the NOS module has never been used it will remember the value of the first key used. They auto-program themselves.
RBob.
To actually test that it's putting out the signal that the ECM needs , an oscilloscope would be the tool of choice . I believe it's a 5 volt signal of either 30 or 50 HZ , but it's been a while since I dealt with VATS so it could be either .
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by OrangeBird
To actually test that it's putting out the signal that the ECM needs , an oscilloscope would be the tool of choice . I believe it's a 5 volt signal of either 30 or 50 HZ , but it's been a while since I dealt with VATS so it could be either .
In the 89 TTA the ECM don’t use that signal; the ECM is the same used in the Grand National and they never had VATS
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by RBob
To set up for bench testing need the harness pigtail, a bulb or LED for the 'security' light, some resistors, P/S and time. As you try each resistor value need to wait 10 minutes with the power off before trying the next value. I know that the service manual states 4 or 5 minutes, but ten works better.
Also, if the NOS module has never been used it will remember the value of the first key used. They auto-program themselves.
RBob.
I got a loose pigtail and for the 3 used modules I got the key # so as long as that is actually correct I know the resistor values to use.
won’t hook up the NOS module just the 3 used ones to make sure they all work
Re: VATS module location / access ... or how to test my spare VATS module ?
Originally Posted by RBob
I believe that is the front of the duct.
RBob.
Ahh yeah, you may be right. I remember seeing the module when I took my dash apart, I knew it was a real bitch to get to, I thought it was on the back of the center duct
Re: VATS module location / access ... or how to test my spare VATS module ?
Found someone on ebay selling the "Dash Center Air Defrost Air Duct" and it clearly shows the VATS module on there so save the picture to help me and others, good reference along with the above replies to my original question.
Re: VATS module location / access ... or how to test my spare VATS module ?
Just to close on this topic .... built a simple bench test harness per attached ... helps check two things:
1. Bulbtest when power on (Switch 1 is on) and if the correct key (pellet) light will go on for a second or two then go out; if wrong key (pellet) the light will stay on and you need to turn off and wait 4 min to reset before trying a new key (pellet).
2. Starter relay test; I was hoping I could simply use a bulb here as well but the load is not enough and I had to use an original relay to see if it all worked .... so if 1 above work (light goes out after a second or two) and I flick switch 2 in my diagram the relay will click and that part works just fine.
I got the Passkey interrogator so that helped specially with one of the VATS modules where I had no clue whish key it was coded for ... well now I know ... but took some time to try all 15 "keys" and have to wait 4 min between each of them ....
So dead easy to bench test (and can be done without the interrogator just use a a ignition key or resistors to simulate each key ...
Note that the outputs/inputs are solid state so do not use anything to try to measure the resistance or you might not have a working module after you're done
10-24-2020, 03:09 AM
Your not gonna like the answer .......
To actually test that it's putting out the signal that the ECM needs , an oscilloscope would be the tool of choice . I believe it's a 5 volt signal of either 30 or 50 HZ , but it's been a while since I dealt with VATS so it could be either . 
