Vats problem
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,699
Likes: 2
From: The Black Hole LA
Vats problem
'90 model
I have a vats problem that has been intermitent thus far but left me stranded today so I am going to do something about it. I know how the system works and I have found the 2way connector under the dash. I'd like to sauder in a resistor so that the ccm never thinks its the wrong key again. Has anyone done this and is there anything (other than not having the VATS anymore) that this could cause a problem with? Also my multimeter when put on ohms reads .877 across the key, would this be within normal reading range?
BTW I have no reading at the plug on the ignition side when the key is in and turned, and all wires are plugged in.
I have a vats problem that has been intermitent thus far but left me stranded today so I am going to do something about it. I know how the system works and I have found the 2way connector under the dash. I'd like to sauder in a resistor so that the ccm never thinks its the wrong key again. Has anyone done this and is there anything (other than not having the VATS anymore) that this could cause a problem with? Also my multimeter when put on ohms reads .877 across the key, would this be within normal reading range?
BTW I have no reading at the plug on the ignition side when the key is in and turned, and all wires are plugged in.
Safety Car
Joined: Jul 2004
Posts: 3,834
Likes: 30
'90 model
I have a vats problem that has been intermitent thus far but left me stranded today so I am going to do something about it. I know how the system works and I have found the 2way connector under the dash. I'd like to sauder in a resistor so that the ccm never thinks its the wrong key again. Has anyone done this and is there anything (other than not having the VATS anymore) that this could cause a problem with? Also my multimeter when put on ohms reads .877 across the key, would this be within normal reading range?
BTW I have no reading at the plug on the ignition side when the key is in and turned, and all wires are plugged in.
I have a vats problem that has been intermitent thus far but left me stranded today so I am going to do something about it. I know how the system works and I have found the 2way connector under the dash. I'd like to sauder in a resistor so that the ccm never thinks its the wrong key again. Has anyone done this and is there anything (other than not having the VATS anymore) that this could cause a problem with? Also my multimeter when put on ohms reads .877 across the key, would this be within normal reading range?
BTW I have no reading at the plug on the ignition side when the key is in and turned, and all wires are plugged in.
Last edited by Da Mail Man; Jul 19, 2008 at 10:43 PM.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You have pellet code 4. The pellet resistance can be 852 to 942 ohms, nominal resistance is 887 ohms. A standard 870 ohm resistor could replace your pellet as long as it isn't lower than 852 ohms. A 5% 870 resistor can be as low as 826 ohms. The most common problem with VATS is the contacts in the ign lock don't make reliable connection to the pellet and a new ign lock has new contacts. I drive my 87 vette every day and I have replaced the ign lock twice for this problem, so the contacts have a 9 year life. I believe your 90 is ok to connect a fixed resistor across the 2 wires in the wiring harness, but I'm not 100% positive. Later C4's require that the key be removed before attempting a restart, so you cannot leave VATS bypassed all the time.
I would recommend that you replace the ign lock because 99% of thefts are done by bashing the column and jumping the ignition. The person I bought my 87 from bought a new 90 vette and one day came out of work to find the window and column busted out, but the vette hadn't budged an inch.
I would recommend that you replace the ign lock because 99% of thefts are done by bashing the column and jumping the ignition. The person I bought my 87 from bought a new 90 vette and one day came out of work to find the window and column busted out, but the vette hadn't budged an inch.
Advanced
Joined: May 2007
Posts: 82
Likes: 1
From: LA California
Melting Slicks
Joined: Apr 2004
Posts: 2,764
Likes: 138
From: cyberspace NY
bypass it temporaily. your problems will be gone.
Then when you have time, replace the lock cylinder. It's a great anti-theft tool.
there is so much anti-vats stuff going around the internet, but then even a high school punk can rob your car. At least with VATS, it takes a professional to steal your car, or a tow truck.
Then when you have time, replace the lock cylinder. It's a great anti-theft tool.
there is so much anti-vats stuff going around the internet, but then even a high school punk can rob your car. At least with VATS, it takes a professional to steal your car, or a tow truck.
Safety Car
Joined: Jul 2004
Posts: 3,834
Likes: 30
bypass it temporaily. your problems will be gone.
Then when you have time, replace the lock cylinder. It's a great anti-theft tool.
there is so much anti-vats stuff going around the internet, but then even a high school punk can rob your car. At least with VATS, it takes a professional to steal your car, or a tow truck.
Then when you have time, replace the lock cylinder. It's a great anti-theft tool.
there is so much anti-vats stuff going around the internet, but then even a high school punk can rob your car. At least with VATS, it takes a professional to steal your car, or a tow truck.
...my vats crapped out on my 3 times so, that is why i did the bypass i did...when i go places i am unfamiliar with, i simply switch the switch to "vats enabled" and get the benefits of a fully working vats system.....
Racer
Joined: Jan 2007
Posts: 274
Likes: 0
From: Muskogee OK
As another check, use the diagnostics that the 90 model came with to troubleshoot.
Jumper pins A & G to read the CCM codes on your speedo display.
If you come up with a C51 or H51, the CCM is not(C for current) or did not (H for history) read the key.
As a back up check, there should be a 1.0 showing on your display. Use the Trip/ODO button to scroll to 1.3. You should see 01 in the odometer display at the bottom. Use the Eng/Met button to scroll to 06 and this should give you a number between 0 and 255. I'm at work and I don't have my FSM handy to confirm that your value matches what jfb gave you, but this is a good start point. I'll check tonight when I get home.
Hopefully, you just have dirty contacts in the switch. If the CCM reading is different, clean the contacts and your key and try again.
You can also disconnect the two wire connector and use a DVM to check key resistance.
I've been through this for the past 4 weeks and finally tracked down my intermittent to a loose or dirty connection on the back of the CCM.
Jumper pins A & G to read the CCM codes on your speedo display.
If you come up with a C51 or H51, the CCM is not(C for current) or did not (H for history) read the key.
As a back up check, there should be a 1.0 showing on your display. Use the Trip/ODO button to scroll to 1.3. You should see 01 in the odometer display at the bottom. Use the Eng/Met button to scroll to 06 and this should give you a number between 0 and 255. I'm at work and I don't have my FSM handy to confirm that your value matches what jfb gave you, but this is a good start point. I'll check tonight when I get home.
Hopefully, you just have dirty contacts in the switch. If the CCM reading is different, clean the contacts and your key and try again.
You can also disconnect the two wire connector and use a DVM to check key resistance.
I've been through this for the past 4 weeks and finally tracked down my intermittent to a loose or dirty connection on the back of the CCM.
Racer
Joined: Jan 2007
Posts: 274
Likes: 0
From: Muskogee OK
Sorry for the delay...
Since I was working off of my usually faulty memory yesterday, I'll post the proper test methoids from the FSM.
Jumper A & G.
The diagnostics should start at 1 for CCM codes then switch to 4 for ECM codes and 7 for Active Suspension, if equipped.
If the problem is VATS, you may have codes C51 or H51 appear in the speedo display. There are several other VATS related codes, so if you have a different one show up and don't have a FSM, post and I'll let you know.
Once all codes have been displayed, 1.0 will show in the display.
Enter manual mode by pressing the Trip/Odo button and scroll to 1.2 instead of 1.3 I posted above.
Once in 1.2 press the Eng/Met button and cycle to 06 which will show at the bottom in the odometer area.
The number that appears is your VATS A/D count. For your key code of 4, the number in the display should read between 64 and 70.
There is a troubleshooting tree in the FSM that lists additional steps, depending on the readings. I won't try to transcribe it now, but if you need help, yell.
Since I was working off of my usually faulty memory yesterday, I'll post the proper test methoids from the FSM.
Jumper A & G.
The diagnostics should start at 1 for CCM codes then switch to 4 for ECM codes and 7 for Active Suspension, if equipped.
If the problem is VATS, you may have codes C51 or H51 appear in the speedo display. There are several other VATS related codes, so if you have a different one show up and don't have a FSM, post and I'll let you know.
Once all codes have been displayed, 1.0 will show in the display.
Enter manual mode by pressing the Trip/Odo button and scroll to 1.2 instead of 1.3 I posted above.
Once in 1.2 press the Eng/Met button and cycle to 06 which will show at the bottom in the odometer area.
The number that appears is your VATS A/D count. For your key code of 4, the number in the display should read between 64 and 70.
There is a troubleshooting tree in the FSM that lists additional steps, depending on the readings. I won't try to transcribe it now, but if you need help, yell.
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Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,699
Likes: 2
From: The Black Hole LA
You have pellet code 4. The pellet resistance can be 852 to 942 ohms, nominal resistance is 887 ohms. A standard 870 ohm resistor could replace your pellet as long as it isn't lower than 852 ohms. A 5% 870 resistor can be as low as 826 ohms. The most common problem with VATS is the contacts in the ign lock don't make reliable connection to the pellet and a new ign lock has new contacts. I drive my 87 vette every day and I have replaced the ign lock twice for this problem, so the contacts have a 9 year life. I believe your 90 is ok to connect a fixed resistor across the 2 wires in the wiring harness, but I'm not 100% positive. Later C4's require that the key be removed before attempting a restart, so you cannot leave VATS bypassed all the time.
I would recommend that you replace the ign lock because 99% of thefts are done by bashing the column and jumping the ignition. The person I bought my 87 from bought a new 90 vette and one day came out of work to find the window and column busted out, but the vette hadn't budged an inch.
I would recommend that you replace the ign lock because 99% of thefts are done by bashing the column and jumping the ignition. The person I bought my 87 from bought a new 90 vette and one day came out of work to find the window and column busted out, but the vette hadn't budged an inch.
Do you have any idea of where to pick resistor in this range up? Radio shack went from 680 - 1K, nothing in between. Or am I just going to have to call all the computer repair stores in town until I find something that will work.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
Replacing the ignition key cylinder would be the best method to solve your problem.
To use a resistor bypass, go to Radio Shack and purchase a 1k variable potentiometer. Using a piece of wire, short and solder together the center lead to one of the outside leads of the potentiometer. Doesn't matter which outer lead.
Solder a piece of wire to the unused lead.
Touch your meter leads to the two wires and with a small blade screwdriver turn the adjustment screw until the reading on the meter is 887 ohms for key code 4. Once that is adjusted you can use a dab of silicone on the adjustment screw so it doesn't change position.
With the two pin Vats key connector at the bottom of the steering column disconnected, attach the two wires to the two pin connector going to the CCM.
Click on the URL below to see the Radio Shack part number.
http://www.radioshack.com/product/in...entPage=search
To use a resistor bypass, go to Radio Shack and purchase a 1k variable potentiometer. Using a piece of wire, short and solder together the center lead to one of the outside leads of the potentiometer. Doesn't matter which outer lead.
Solder a piece of wire to the unused lead.
Touch your meter leads to the two wires and with a small blade screwdriver turn the adjustment screw until the reading on the meter is 887 ohms for key code 4. Once that is adjusted you can use a dab of silicone on the adjustment screw so it doesn't change position.
With the two pin Vats key connector at the bottom of the steering column disconnected, attach the two wires to the two pin connector going to the CCM.
Click on the URL below to see the Radio Shack part number.
http://www.radioshack.com/product/in...entPage=search
Last edited by Hooked on Vettes; Jul 22, 2008 at 11:21 PM.