Ignition key ohm measurement
12-29-2005, 04:21 PM
#1
Ignition key ohm measurement I know that there are 12 different resistor chips that GM used in our keys, but does anyone know what the ohm reading should be. I think my key took a permanent vacation causing my car to not start. Can a few of you ohm test your keys to give me an idea of what it should be?
Thanks
Thanks
12-29-2005, 04:28 PM
#2
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try:
https://ls1tech.com/usa/showthread.p...light=VATS+OHM
standard 5% resistor values if I remember right....
https://ls1tech.com/usa/showthread.p...light=VATS+OHM
standard 5% resistor values if I remember right....
12-29-2005, 05:31 PM
#4
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A replacement Key from GM is 80 bucks!
Now either the key is worn, or the little spring contacts inside the ignition lock cylinder are worn. in which case, it will most likely be expensive as **** to fix!!
The alternative: Disabling The VATS system
IMPORTANT: anyone could steal your car (highly unlikely but you never know) after that so weigh your options first!! I didnt wanna spend 80 dollars for a replacement key on my 1989 camaro so i disabled the VATS
What you will need:
You can get these things from radio shack
1.)digital voltmeter/ohmmeter (inexpensive) Or free if u can borrow one
2.)Resistors (cheap as hell for a big assorted pack of them)
3.) Preferbly a soldering gun & solder (if u want a secure connection) or electrical tape will do
4.) Wire cutter/strippers
Step 1) Borrow/buy a digital volt/ohm meter . you can get one cheap from radio shack. Get the big bag of the assorted resistors too
Step 2) Touch the contacts of the ohm meter to the ends of the key resistor. That'll give you the resistance of the key
Step 3) if need be, you might have to combine a few resistors to equal the key's resistance. you dont have to worry about getting them 100% correct, i was a few ohms off, but no more than 2 or 3. Soldering the resistors together is the best option which will ensure that they stay together.
Step 4) Pull down the panel below the steering column and you should find 2 skinny wires. the wires will be coming from the ignition lock cylinder where your key goes. just follow that and down from the key youll find a little connector in between them. disconnect that connector, and on the ECM side of the wire, cut that connector off, strip the ends of the wire, and splice the resistor, I too soldered those connections and it will bypass the VATS.
I did this on my 1989 camaro and my friend's 1989 camaro and it worked fine, i wasnt worried about anyone stealing it, since i had my fuel pump hooked up to a switch hehehe.
Its not as complicated as u might think.
I hope this bit helps you!!
Ron
Now either the key is worn, or the little spring contacts inside the ignition lock cylinder are worn. in which case, it will most likely be expensive as **** to fix!!
The alternative: Disabling The VATS system
IMPORTANT: anyone could steal your car (highly unlikely but you never know) after that so weigh your options first!! I didnt wanna spend 80 dollars for a replacement key on my 1989 camaro so i disabled the VATS
What you will need:
You can get these things from radio shack
1.)digital voltmeter/ohmmeter (inexpensive) Or free if u can borrow one
2.)Resistors (cheap as hell for a big assorted pack of them)
3.) Preferbly a soldering gun & solder (if u want a secure connection) or electrical tape will do
4.) Wire cutter/strippers
Step 1) Borrow/buy a digital volt/ohm meter . you can get one cheap from radio shack. Get the big bag of the assorted resistors too
Step 2) Touch the contacts of the ohm meter to the ends of the key resistor. That'll give you the resistance of the key
Step 3) if need be, you might have to combine a few resistors to equal the key's resistance. you dont have to worry about getting them 100% correct, i was a few ohms off, but no more than 2 or 3. Soldering the resistors together is the best option which will ensure that they stay together.
Step 4) Pull down the panel below the steering column and you should find 2 skinny wires. the wires will be coming from the ignition lock cylinder where your key goes. just follow that and down from the key youll find a little connector in between them. disconnect that connector, and on the ECM side of the wire, cut that connector off, strip the ends of the wire, and splice the resistor, I too soldered those connections and it will bypass the VATS.
I did this on my 1989 camaro and my friend's 1989 camaro and it worked fine, i wasnt worried about anyone stealing it, since i had my fuel pump hooked up to a switch hehehe.
Its not as complicated as u might think.
I hope this bit helps you!!
Ron
12-29-2005, 09:05 PM
#5
i have pondered that idea, but living in the chicago area it would probably prove to be a bad idea. I tested the key at .68 ohms, so i'm pretty sure the key is dead. GM quoted me a price of 31.75 for a key 
so I will be there tomorrow getting a new one. If that doesn't work they quoted me a price of 101.xx for the key cylinder that connects to the vats system. So one way or another I think i've narrowed it down.
so I will be there tomorrow getting a new one. If that doesn't work they quoted me a price of 101.xx for the key cylinder that connects to the vats system. So one way or another I think i've narrowed it down.
12-30-2005, 09:15 AM
#6
A replacement Key from GM is 80 bucks!
there are 12 different resistor chips that GM used in our keys
Hope this helps (at least a little)
Kelly
12-30-2005, 10:08 PM
#7
ditto to that only there are 15 chip codes. Fixed the problem thanks to HP tuners assisting with a little troubleshooting. Turned out not to be anything to do with VATS at all. Key was good when the dealer tested it and I disabled VATS to see if it made any difference. It didn't. I did bypass the switch below the clutch, and that wasn't it. It appeared to be a switch above the clutch that wasn't adjusted correctly. i guess anything is possible when the car sits for 2 years 
So now the speedo is acting like the tach and the tach doesn't move at all. i am thoroughly confused now. Any ideas?
So now the speedo is acting like the tach and the tach doesn't move at all. i am thoroughly confused now. Any ideas?
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12-31-2005, 07:53 PM
#8
Originally Posted by NO-OPTION-2002
WOW!!!, I'm not sure where your going, but at my dealership, VATS chip keys are $25.
01-01-2006, 07:05 PM
#9
are you sure it's not 80 bucks for the Alarm Fob? I went to the dealership in one of the most expensive areas and it was 45 bucks.
edit: wrong section to post something like this
edit: wrong section to post something like this
05-16-2017, 07:09 AM
#11
No. The resistance is in the key pellet. If you don't have the key then there is no resistance to measure.
If you don't have the key then your only option is to determine the correct value by trial and error (or you could buy a brand new BCM and a key with any resistance value because the new BCM will program itself to whatever resistor is on the first key used). The trial and error method involves getting the necessary resistors (online or at Radio Shack) to match each of the 14 standard values used for VATS and then try each until you find the value that allows starting the car and makes the security light turn off. Directed Electronics (makers of Viper and Clifford alarm systems) makes a kit part #652T that includes all the resistors in one package for around $25. DO NOT buy a kit from NEWROCKIES Inc!! Their $280 kit is a complete ripoff.
If you don't have the key then your only option is to determine the correct value by trial and error (or you could buy a brand new BCM and a key with any resistance value because the new BCM will program itself to whatever resistor is on the first key used). The trial and error method involves getting the necessary resistors (online or at Radio Shack) to match each of the 14 standard values used for VATS and then try each until you find the value that allows starting the car and makes the security light turn off. Directed Electronics (makers of Viper and Clifford alarm systems) makes a kit part #652T that includes all the resistors in one package for around $25. DO NOT buy a kit from NEWROCKIES Inc!! Their $280 kit is a complete ripoff.
05-16-2017, 08:08 AM
#12
No. The resistance is in the key pellet. If you don't have the key then there is no resistance to measure.
If you don't have the key then your only option is to determine the correct value by trial and error (or you could buy a brand new BCM and a key with any resistance value because the new BCM will program itself to whatever resistor is on the first key used). The trial and error method involves getting the necessary resistors (online or at Radio Shack) to match each of the 14 standard values used for VATS and then try each until you find the value that allows starting the car and makes the security light turn off. Directed Electronics (makers of Viper and Clifford alarm systems) makes a kit part #652T that includes all the resistors in one package for around $25. DO NOT buy a kit from NEWROCKIES Inc!! Their $280 kit is a complete ripoff.
If you don't have the key then your only option is to determine the correct value by trial and error (or you could buy a brand new BCM and a key with any resistance value because the new BCM will program itself to whatever resistor is on the first key used). The trial and error method involves getting the necessary resistors (online or at Radio Shack) to match each of the 14 standard values used for VATS and then try each until you find the value that allows starting the car and makes the security light turn off. Directed Electronics (makers of Viper and Clifford alarm systems) makes a kit part #652T that includes all the resistors in one package for around $25. DO NOT buy a kit from NEWROCKIES Inc!! Their $280 kit is a complete ripoff.
Unfortunately that kit seems to be unavailable at the moment, so I'm thinking about the BCM replacement option. If I got your word right, I should get and cut a new key (with any resistance value), then replace BCM with the new (actually remanufactured) one. The new BCM would recognize the new key as having the correct resistance and start the car therefore. Did I get it right?
Thanks again for your help.
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Alan Lowery (05-02-2021)
05-16-2017, 08:16 AM
#13
I found the 652T kit on ebay for just $5.38 with free shipping and on Amazon for $4.95.
Yes, the new (or remanufactured) BCM will match itself to the first ignition key it sees after installation. Simply install the BCM, insert an ignition key with any of the standard resistor chip values, turn the key on but don't start the car, wait a few seconds for the warning light bulb test to complete, then turn off the ignition - your BCM is programmed.
Yes, the new (or remanufactured) BCM will match itself to the first ignition key it sees after installation. Simply install the BCM, insert an ignition key with any of the standard resistor chip values, turn the key on but don't start the car, wait a few seconds for the warning light bulb test to complete, then turn off the ignition - your BCM is programmed.
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Alan Lowery (05-03-2021)
05-16-2017, 08:51 AM
#14
I found the 652T kit on ebay for just $5.38 with free shipping and on Amazon for $4.95.
Yes, the new (or remanufactured) BCM will match itself to the first ignition key it sees after installation. Simply install the BCM, insert an ignition key with any of the standard resistor chip values, turn the key on but don't start the car, wait a few seconds for the warning light bulb test to complete, then turn off the ignition - your BCM is programmed.
Yes, the new (or remanufactured) BCM will match itself to the first ignition key it sees after installation. Simply install the BCM, insert an ignition key with any of the standard resistor chip values, turn the key on but don't start the car, wait a few seconds for the warning light bulb test to complete, then turn off the ignition - your BCM is programmed.
Thanks a lot
05-16-2017, 10:01 AM
#15
I found the 652T kit on ebay for just $5.38 with free shipping and on Amazon for $4.95.
Yes, the new (or remanufactured) BCM will match itself to the first ignition key it sees after installation. Simply install the BCM, insert an ignition key with any of the standard resistor chip values, turn the key on but don't start the car, wait a few seconds for the warning light bulb test to complete, then turn off the ignition - your BCM is programmed.
Yes, the new (or remanufactured) BCM will match itself to the first ignition key it sees after installation. Simply install the BCM, insert an ignition key with any of the standard resistor chip values, turn the key on but don't start the car, wait a few seconds for the warning light bulb test to complete, then turn off the ignition - your BCM is programmed.
05-16-2017, 11:44 AM
#16
There is no Theft Deterrent Module on 97-02 F-bodies. The TDM was used on earlier models that didn't have a BCM. The earlier models had a TDM and a separate remote keyless entry module that were combined (along with other functions such as the optional alarm system) into the BCM starting with the 97 model.
05-16-2017, 02:00 PM
#17
There is no Theft Deterrent Module on 97-02 F-bodies. The TDM was used on earlier models that didn't have a BCM. The earlier models had a TDM and a separate remote keyless entry module that were combined (along with other functions such as the optional alarm system) into the BCM starting with the 97 model.
05-16-2017, 02:40 PM
#18
That is information that would have been helpful earlier.
'89 was the last year C4 'Vette in which a static VATS bypass would work. Starting with the '90 model, the system had to see the key removed and inserted so simply wiring resistors in place no longer worked. So you're lucky there. However, the VATS module (also called TDM or decoder module) is mounted inside the dash behind the passenger side airbag and is difficult to access. I assume a new VATS module would self-program in the same way as a BCM but I don't know that for sure. A bypass with resistors can be done under the driver's side of the dash (near base of the steering column) so it might be the easier option... certainly less expensive.
You might want to check out vatssucks.com or the corvetteforum.com forums for more detailed information. Corvettes are a little outside my experience.
'89 was the last year C4 'Vette in which a static VATS bypass would work. Starting with the '90 model, the system had to see the key removed and inserted so simply wiring resistors in place no longer worked. So you're lucky there. However, the VATS module (also called TDM or decoder module) is mounted inside the dash behind the passenger side airbag and is difficult to access. I assume a new VATS module would self-program in the same way as a BCM but I don't know that for sure. A bypass with resistors can be done under the driver's side of the dash (near base of the steering column) so it might be the easier option... certainly less expensive.
You might want to check out vatssucks.com or the corvetteforum.com forums for more detailed information. Corvettes are a little outside my experience.
05-18-2017, 05:29 AM
#19
That is information that would have been helpful earlier.
'89 was the last year C4 'Vette in which a static VATS bypass would work. Starting with the '90 model, the system had to see the key removed and inserted so simply wiring resistors in place no longer worked. So you're lucky there. However, the VATS module (also called TDM or decoder module) is mounted inside the dash behind the passenger side airbag and is difficult to access. I assume a new VATS module would self-program in the same way as a BCM but I don't know that for sure. A bypass with resistors can be done under the driver's side of the dash (near base of the steering column) so it might be the easier option... certainly less expensive.
You might want to check out vatssucks.com or the corvetteforum.com forums for more detailed information. Corvettes are a little outside my experience.
'89 was the last year C4 'Vette in which a static VATS bypass would work. Starting with the '90 model, the system had to see the key removed and inserted so simply wiring resistors in place no longer worked. So you're lucky there. However, the VATS module (also called TDM or decoder module) is mounted inside the dash behind the passenger side airbag and is difficult to access. I assume a new VATS module would self-program in the same way as a BCM but I don't know that for sure. A bypass with resistors can be done under the driver's side of the dash (near base of the steering column) so it might be the easier option... certainly less expensive.
You might want to check out vatssucks.com or the corvetteforum.com forums for more detailed information. Corvettes are a little outside my experience.
05-18-2017, 06:41 AM
#20
Certainly a bypass can be done without a key. It just takes longer because you have to try each of the standard resistor values until you get to the one that matches. There are 15 different values on earlier vehicles like yours - only 14 of those were used in later vehicles.
Bear in mind that the key you get with the used module will almost certainly not work with your ignition. You'll have to measure the resistance on the pellet and then get a new key cut that matches the cuts of your original but has the resistance value of the new module. That may not be cheap - I've heard of dealers charging $80 or more for a new key.
Bear in mind that the key you get with the used module will almost certainly not work with your ignition. You'll have to measure the resistance on the pellet and then get a new key cut that matches the cuts of your original but has the resistance value of the new module. That may not be cheap - I've heard of dealers charging $80 or more for a new key.