Lost key. Got New One Cut Now it gots the car with the lock only before starting

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Tahoeking12345

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He said the security light goes off and it will run for 10 min or so. So I wouldn't think it's a security issue. I believe that the RPMs are limited in Park.

The '03 should have the Passlock system, so IF that needs to be reset here's the procedure:

View attachment 415867
could i buy a key fob from auto zone ? Would that do anything.
 

B-train

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No, you need to do a relearn of the key, a fob wont help. The BCM measures the resistance of the key and knows when a "fake" is put in. Hence teaching it to accept it. The whole process is to deter theft with the time required for the process. IF you had 1 good key, you can do the KEY ON, ENGINE OFF with known good key. Then shut off and insert new key immediately and do the same and then start it. The BCM will accept new key as a trusted fellow since he came with his buddy on the approved list.

I had to do this with a new ECM in my 2005 duramax pickup. It was a PITA, but can be done. I think the other option is via a tech2 scanner.
 
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Tahoeking12345

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No, you need to do a relearn of the key, a fob wont help. The BCM measures the resistance of the key and knows when a "fake" is put in. Hence teaching it to accept it. The whole process is to deter theft with the time required for the process. IF you had 1 good key, you can do the KEY ON, ENGINE OFF with known good key. Then shut off and insert new key immediately and do the same and then start it. The BCM will accept new key as a trusted fellow since he came with his buddy on the approved list.

I had to do this with a new ECM in my 2005 duramax pickup. It was a PITA, but can be done. I think the other option is via a tech2 scanner.
Tried the key thing it ran good for 10 min then stalled. Fired back ran good but ima try a fuel filter ? Regulator today I’ll be back
 

OR VietVet

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Go to a local locksmith and they can do key fobs quickly. At least my local locksmith did it for me recently---15 minutes, in and out the door.
 
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Tahoeking12345

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truck stalled out buddy got out and hit the tank fired right up. 5 mins prior stalled out took 3 try’s jus to start back up fuel pump hopefully in by Saturday evening thanks guys be back in touch
 

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A fuel pressure test would confirm your diagnosis before replacing the fuel pump. Also, if there's a fuel filter, change that while you have the fuel pressure off for the pump replacement.
 

rockola1971

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No, you need to do a relearn of the key, a fob wont help. The BCM measures the resistance of the key and knows when a "fake" is put in. Hence teaching it to accept it. The whole process is to deter theft with the time required for the process. IF you had 1 good key, you can do the KEY ON, ENGINE OFF with known good key. Then shut off and insert new key immediately and do the same and then start it. The BCM will accept new key as a trusted fellow since he came with his buddy on the approved list.

I had to do this with a new ECM in my 2005 duramax pickup. It was a PITA, but can be done. I think the other option is via a tech2 scanner.
There is not a resistor(AKA Chip) on the 03 tahoe/yukon keys. The only thing the passlock system is looking for is just a metal key. The version of passlock is the passlock II in the 03 and it has a magnetic sensor that just wants to see a metal key in its "view". I own (2) 2003 Tahoe LT's and you can walk in and have key copy made, walk out and drive home with no problems involving the key copy. OP didnt state where he was so its possible this involves a european or what not version and I do know they have different versions of passlock than us on some models/years.
Basically the only thing passlock II is really good for is when a thief pops the ignition with a t-handle and breaks the lock. Passlock will shut the vehicle down within 10 secs after starting.
I can get more detailed if the crew really wants to know more about the passlock II system and what actually happens from key to engine start.
The chain of events goes like this: Magnetic sensor looks for key > sends "code" to BCM > BCM send enable/disable "code" to PCM. This is a basic summary, not all info is there.
 

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