Possible key transponder workaround

[Telco]

Seems like enough folks here have problems with their keys, needing to be married to the PCM, that I thought I'd start this thread. How exactly does the PCM recognize keys on this car? Is it an actual circuit or is the keylock measuring resistance on the key? If it's the latter, it might be possible to install a resistor in the circuit and never again need a special key to start the car. GM cars with the PASSLOCK system from the same year range as the LS so I'm thinking that since the OEMs do share some tech in certain areas that perhaps Ford used a similar system.

Anyway, thoughts? Am I on to something useful or just running with my degas cap loose?

 

[don-ohio]

Another slam.....I feel really important! don-ohio ^)

 

[1LoudLS]

ok, if you are familiar with GM systems, Ford's PATS is extremely similar to Chevy's PassKey3 (sometimes called PassLock3)

it is noting like VATS with the resistor in the key or Passlock I or II with a resistor in the ignition cylinder that gets activated when the key cylinder is turned with a key, and while some of GM cars from around the same time still used PLI or PLII, its kind of a legacy thing as its a real old tech from GM(started in the late 80's) and should have if they(GM) were smart, once they came out with a new version, they would implement it across the board (or at least as each vehicle was updated)

It is a wireless transponder system. the RF chip in the key gets "excited" when placed close to the PATS antenna/receiver which is a circle around the ignition cylinder, when excited, it emits a very specific signal that the antenna receives, then the cluster either recognizes or reject the code and tells the PCM to either let the car start or not to let the car start.




nobody here is having problem with their keys, there are only people here that might be having problems with their PCMs, and changing the PCM require that the cluster and PCM be married together (which also requires that the two keys be present)

even if somebody could trick the cluster into thinking the correct key is there, a new PCM would still require a dealer or a good scan tool to marry it with the cluster...

 

[Telco]

Another slam.....I feel really important! don-ohio ^)

You shouldn't. You should feel more like Scoutmaster Glenn Taylor.

 

[Telco]

oh, if you are familiar with GM systems, Ford's PATS is extremely similar to Chevy's Passkey3

it is noting like VATS with the resistor in the key or Passlock I or II with a resistor in the ignition cylinder that gets activated when the key cylinder is turned with a key


It is a wireless transponder system, the RF " chip in the key is excited when placed close to the PATS antenna/receiver which is a circle around the ignition cylinder, when excited, it emmits a very specific signal that the antenna receives, then the cluster either recognizes or reject the code and tells the PCM to either let the car start or not to let the car start.




nobody here is having problem with their keys

I know nobody's having problems with their keys like GM does, considering their system shuts the car down when the key gets worn. I had to shut that system down on my daughter's car to keep her safe.

Occasionally there's an issue where people have to marry their keys to their cars, which is what I was hoping to address. If this is not something that needs to be addressed, never mind then.

 

[1LoudLS]

well GM's problem is not due to the PassLock system or worn keys at all, there problem is that the sh!tty key cylinders were too east to rotate (especially with a lot of crap on the key ring) and the ignition itself was getting turned off, therefore turning the engine off and causing accidents(and not allowing the air bag system to function), this is why GM's original fix was to put a plug in the key to keep the key ring centered in the key hoping the the weight didn't cause the key to be as easily turned.



A lot of the PLI and PLII cars are just like the ford system, in the fact that they are only active a few seconds after the car is started. you start the car, then a couple of seconds later the car looks for the correct resistance, if it does not see it, then it shuts the car off. however if it sees the correct resistance, the motor stays running and then the car does not check it again during the run cycle. however there is a car or two (a Saturn or two) that does need to see the code the whole time the engine is running (I though but am not sure that after a few seconds, the car will still be running but with set off a security light and code)


however if this concern you have for your daughters safety is due to all the recalls/lawsuits/deaths that have been in the news the past couple of years, the problem is the switch detent (the part that causes the "click" feel each time the key is turned to a different position) and should keep the key from accidentally being turned by itself is too weak to do its job. the only way to correct this fatal flaw is to replace the entire key cylinder with the newer and stronger updated part number.

 

[RigsLS]

Loud, you mean to tell me my key gets excited when it's about to start the LS? That's Fn awesome, at least something gets excited to run these money pits! j/k

 

[joegr]

Anti-Theft — Passive Anti-Theft System (PATS) Printable View (9 KB)

The PATS uses radio frequency identification technology to deter a driveaway theft. Passive means that it does not require any action from the user to make it functional.

PATS uses a specially encoded ignition key. Each PATS key contains a permanently installed electronic device called a transponder. Each transponder contains a unique electronic identification code, with over 72 million billion combinations.

Each PATS key must be programmed into the vehicle PATS module before it can be used to start the engine. There are special diagnostic procedures described in the workshop manual that must be carried out if new PATS keys are to be installed. Refer to General Procedures in this section.

The PATS key is larger than a traditional ignition key. The PATS key does not require batteries and should last the life of the vehicle.

The transceiver module communicates with the PATS key. This module is located in the instrument panel attached to the ignition lock cylinder housing. During each vehicle start sequence, the transceiver module reads the PATS key identification code and sends the data to the instrument cluster. The instrument cluster validates the code as correct and sends the powertrain control module (PCM) an enable code through the network.

The control function is contained in the instrument cluster. This module carries out all of the PATS functions, such as receiving the identification code from the PATS key and controlling the starter enable signal, and communicates with the PCM to enable the engine. The instrument cluster initiates the key interrogation sequence when the PATS key is inserted in the ignition switch and also when the switch is turned to RUN or START.

The PATS module uses the instrument cluster to enable or disable the engine. All elements of PATS must be functional before the engine is allowed to start. If any of the components are not working correctly, the vehicle does not start.

NOTE: If either the instrument cluster or the PCM are installed, both modules require a parameter reset. Failure to carry out the parameter reset to both the instrument cluster and PCM may result in a no-start condition.

PATS uses a visual anti-theft indicator. This indicator proves out for 3 seconds when the ignition switch is turned to RUN or START under normal operation. If there is a PATS concern, this anti-theft indicator either flashes rapidly or glows steadily (for more than 3 seconds) when the ignition switch is turned to RUN or START.

PATS is not compatible with aftermarket remote start systems, which allow the vehicle to be started from outside the vehicle. These systems may reduce the vehicle security level, and also may cause no-start issues. Remote start systems must be removed before investigation of PATS-related no-start issues.

 

[oddball]

Loud, sure that the GM system only checks at startup? The PCM calls it "Fuel Enable".....
I just went through that headache on a LT1 swap into a '49 Chevy. Some cheap no-name VATS module died, but it was well hidden, and the PCM wasn't throwing a P46. That took a while.

 

[All2kool]

I had to install a resistor chip in my 1986 Corvette and my 1988 Trans Am as the VATS would fail me at the worst time. GM had the sense to actually have a link in the wire going to the ignition and the resistor was available from a locksmith for $20. It took all of five minutes to install.

 

[grizzlyls]

Had to chuckle, all the talk about a couple bucks and a few minutes bypasses the Chevy anti theft system. I know we all groan at some of the design issues in our babies, but its stuff like this that reassures me why I never owned GM.

 

[cammerfe]

Loud, sure that the GM system only checks at startup? The PCM calls it "Fuel Enable".....
I just went through that headache on a LT1 swap into a '49 Chevy. Some cheap no-name VATS module died, but it was well hidden, and the PCM wasn't throwing a P46. That took a while.

Your problem comes from using the wrong sort of engine in your chib!!

KS

 

[1LoudLS]

Loud, sure that the GM system only checks at startup? The PCM calls it "Fuel Enable".....

depends on the car... when we put remote start system in passlock cars, sometimes the bypass (a relay and a resistor) gets triggered only while the engine is cranking, some get triggered the whole time the car is running.

 

[1LoudLS]

Had to chuckle, all the talk about a couple bucks and a few minutes bypasses the Chevy anti theft system. I know we all groan at some of the design issues in our babies, but its stuff like this that reassures me why I never owned GM.

are you talking about how easy it is to bypass? cause if so you actually need the key to find out what the resistance actually is (there are many many different values for any given model) so you cant just hop into a car and know ahead of time what resistor you need to wire in... and on top of that, if you figured that you would just try them until found the right one, the BCM will go into short term lock out mode if the wrong resistance is used (15 minutes) and if the wrong resistance is read three times, then it goes into long term lock out mode and even with the correct key, cant be started for one hour. honestly, while not perfect, it wasn't too bad of a system for something that was started in the mid 80's... at least they were trying something instead of ford just making cars that could be hot wired and stolen extremely easy...

 

[Telco]

Actually not on the key issue as my daughter doesn't hang anything off the key. Her key was not rotating, the computer was deciding that the key was not the correct key and would shut the car off. When it shuts off, it would take up to 30 minutes to reset. The fix for my daughter's car was a buddy of mine has Tunercats software, and he shut off the PATS system in the BCM. The EFI Live I have is great software but it doesn't talk to the BCM. I thought that it might be a key issue at first so I installed a new key assembly, but the problem continued after that.

On the resistor fix, you don't have to know the correct key resistance. You install the resistor between two wires, perform a reset procedure which involves turning the key on and off 3 times then leaving it on the third time for 10 minutes, something along those lines. Once the reset is complete you never have the problem again. If you're stupid enough to spend 30 minutes on the job you can steal a Malibu pretty easily, but then anyone willing to steal a Malibu would be that stupid.

 

[All2kool]

Had to chuckle, all the talk about a couple bucks and a few minutes bypasses the Chevy anti theft system. I know we all groan at some of the design issues in our babies, but its stuff like this that reassures me why I never owned GM.

The VATS on a GM is a resistor in the key itself and as the Key and Lock Cylinder age, the tend to lose contact with each other. In order to install a chip to bypass the VATS, you need to know which # it is of course. And then only you will know that it's installed. The theft deterrent is still active unless you put a Post-It on the window letting thieves know otherwise.

 

[1LoudLS]

The VATS on a GM is a resistor in the key itself and as the Key and Lock Cylinder age, the tend to lose contact with each other. In order to install a chip to bypass the VATS, you need to know which # it is of course. And then only you will know that it's installed. The theft deterrent is still active unless you put a Post-It on the window letting thieves know otherwise.

or you could be lazy like this Eldo that I had to put a new starter in this past winter and just solder the key itself to the resistance and reference wires in the steering column! firs time I've seen that done, got a good chuckle out of it.

 

[Telco]

Had to chuckle, all the talk about a couple bucks and a few minutes bypasses the Chevy anti theft system. I know we all groan at some of the design issues in our babies, but its stuff like this that reassures me why I never owned GM.

Yes, but we GM fans don't try to defend instances of crap engineering like it's the best thing since trans-fat margarine.