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My car key unlocks and locks the doors of my G37, but can not start the car from the push button, nor when it is held touching the push button(or in receptacle). Because it can unlock the car, it must be transmitting the right program code right? Or is there a different part of the key that works with the start button ignition? Can I rule out any problem with my key given that it unlocks the doors?

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  • Does your second key start the engine? That would more or less rule out an issue on the car side. As correctly mentioned by narkeleptk, opening doors and starting the engine are independent systems, both in the car as well as in the key. Does keyless entry work using your key in question? Jan 31 at 22:56
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The prox, keyless entry and transponder on button are all different circuits inside the key. So you cant fully rule out the key just yet. It could still be half damaged. The first thing I would do would be to check the key with a transponder reader to see if its present, my guess is you will not have the tool to do this tho. Maybe open it up and check for liquid damage but until you can rule the key is good or bad then its hard to move forward. I have fixed this same situation many times on the same and similar Nissan cars and it has been for many different reasons. Sometimes key, sometimes corrupt data in BCM, sometimes bad ECM. Are you able to extract any DTC's from the ECU and/or BCM?

  • prox = proximity feature (push to start when in range)
  • transponder = when you hold remote it to the button
  • keyless entry = unlock/lock/panic/trunk
  • ecm= engine control module
  • bcm= body control module (where immobilizer data is stored)

I would advise against trying to program new keys until you know more about if your original is bad or good. The BCM is easy to corrupt on these models.

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Many wireless car key ignition systems have some relay or fuse to start cranking the engine. You can start to diagnose the relay or the fuse if it still working or not, do not judge the key is broken too fast. :)

Here is the car key system, check it there are fuses in this kit:the kit

And here is the diagram of a common wireless car key system: Diagram

And this one too with the symbol of F (that is a relay) relay

Diagnose all of these parts:

  • Fuse from the fuse box or the fuse near the starter relay (usually).
  • Cable connection from the wireless module to your starter relay and to your starter, check the continuity.
  • Relay, check if the relay working properly.
  • The wireless module check if there is a voltage output to the starter relay from your wireless module. (check with a voltmeter, the lead test to the pin on the relay or the output pin wireless module, and start clicking your key)

The relay should be made a sound like clicking metal (sounds like the flasher for turn lamp), if there is no sound at all while you click the key probably your relay doesn't get the voltage or it's broken :)

Here is the pin layout of the 5 pin relay: 5pin relay

4pin relay layout: 4pin relay

86+85 is your voltage input (the polarity doesn't matter) for making the relay working to contacting the pin 30 to 87.

30 usually from the battery, fused. Or it could be 87 from the battery and the other one to device eg: to your starter motor.

I hope this one could help you out to understand how the wireless car key system working to ignite your car :)

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