One physical key starts car, the other won't
Discussion
Hi. Puzzling over this. 99 Hyundai, both keys lock/unlock car physically or with fob. Both keys turn starter motor when trying to start the engine. One key never fires the engine, the other does. Every time. Tried about a dozen times, so this is not coincidence.
Doesn't seem likely this car reads information from the key on starting, but I don't know enough about it to say.
Any ideas? One more piece of information. The key that doesn't start the engine has taken a battering over the years, so could be more worn. In fact I've had to replace the damaged plastic casing and hinge before. Now only used as a spare so not sure how long this key fails to start the car.
Doesn't seem likely this car reads information from the key on starting, but I don't know enough about it to say.
Any ideas? One more piece of information. The key that doesn't start the engine has taken a battering over the years, so could be more worn. In fact I've had to replace the damaged plastic casing and hinge before. Now only used as a spare so not sure how long this key fails to start the car.
KnucklesTheDog said:
Hi. Puzzling over this. 99 Hyundai, both keys lock/unlock car physically or with fob. Both keys turn starter motor when trying to start the engine. One key never fires the engine, the other does. Every time. Tried about a dozen times, so this is not coincidence.
Doesn't seem likely this car reads information from the key on starting, but I don't know enough about it to say.
Any ideas? One more piece of information. The key that doesn't start the engine has taken a battering over the years, so could be more worn. In fact I've had to replace the damaged plastic casing and hinge before. Now only used as a spare so not sure how long this key fails to start the car.
They probably have an imboliser chip in the fob. Try taping the fobs together and starting with the dud key. Doesn't seem likely this car reads information from the key on starting, but I don't know enough about it to say.
Any ideas? One more piece of information. The key that doesn't start the engine has taken a battering over the years, so could be more worn. In fact I've had to replace the damaged plastic casing and hinge before. Now only used as a spare so not sure how long this key fails to start the car.
Edited by How u doing on Sunday 2nd May 16:07
I can't speak for Hyundai by Chevrolet (GM) cars from that era had a resistor in the physical key. Unless the physical key has the correct value resistor the car won't start. This is in addition to any activity with the electronic key fob. It was called the VATS system and there were 15 different resistor values. A key with an incorrect resistor, or a broken resistor, will not work.
"There is a resistor embedded on the ignition key. When the key is inserted into the lock and turned, an electrical current runs through the resistor. The amount of current reduction caused by the resistor is measured. If the current reduction matches what the vehicle's system expects, the car is allowed to start. If the current reduction is higher or lower than what the vehicle's system expects, the vehicle will be prevented from starting - even with the correct key - for several minutes. No alarm sounds and the only indication that the vehicle has been disabled is an indicator on the dash."
A quick google suggests Hyundai may have been using the same thing,
https://www.hyundai-forums.com/threads/anti-theft-...
"There is a resistor embedded on the ignition key. When the key is inserted into the lock and turned, an electrical current runs through the resistor. The amount of current reduction caused by the resistor is measured. If the current reduction matches what the vehicle's system expects, the car is allowed to start. If the current reduction is higher or lower than what the vehicle's system expects, the vehicle will be prevented from starting - even with the correct key - for several minutes. No alarm sounds and the only indication that the vehicle has been disabled is an indicator on the dash."
A quick google suggests Hyundai may have been using the same thing,
https://www.hyundai-forums.com/threads/anti-theft-...
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