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Dave Nova
Dave Nova, GMC Technician
Category: GMC
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Experience:  ASE Master Certification. GM World Class Certification
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GMC Yukon Denali: how do i reset the anti theft system in a

Resolved Question:

how do i reset the anti theft system in a 1999 yukon denali
Submitted: 5 years ago.
Category: GMC
Expert:  Dave Nova replied 5 years ago.
Hello and thank you for using Justanswer. My name is XXXXX XXXXX I will do my best to help you with your GMC problem.
Did the security light go off after leaving the key on for 10 minutes?
Customer: replied 5 years ago.
light stays on the entire time
Expert:  Dave Nova replied 5 years ago.
Try the procedure again, this time turning the key to Start, then letting the key return to the ON position. Leave the key on for 10 minutes and see if the light goes out, then turn key off for 5 seconds. Repeat this procedure two more times for a total of 30 minutes. Let me know what happens.
Customer: replied 5 years ago.
will do
Expert:  Dave Nova replied 5 years ago.
Thanks. Let me know when you can.
Customer: replied 5 years ago.
no change the security light stays on entire time. tried your procedure two times to no about some history as to what led us here.had fuel injector spider replaced in dec ran ok for a month then had to have the oxy sensor replaced, all work done at firestone.then it ran good until mid feb at which point it began intermittently dying. would die at traffic light or at speed on freeway.when it would die usually all we had to do was dropp it into neutral and after 15 or 30 seconds it would start normally.two weeks ago the truck stalled and would not start as usual.we checked for ign spark and there was none we replaced the crank position sensor and the truck started but after aXXXXXat speed it died again turned it off and tried to restart , it finally started with a very loud backfire and heavy gas smell.two more miles and it died again this time it would not restart. checked ign spark and had no fire. determined that the battery had a dead cell so we replaced that is where we are now we have ign spark but when we try to start it will only run for about 2 seconds not even long enough to really get going.after researching on web i came to conclusion anti theft has been activated do you think i am wrong. am at wits end please help
Expert:  Dave Nova replied 5 years ago.
When starting the vehicle, does the security light stay on or flash?
Customer: replied 5 years ago.
goes off when starter is cranking but comes back on when key released to on position
Expert:  Dave Nova replied 5 years ago.
Do you have a fuel pressure guage? If you do, connect it to the test port on top of the engine and monitor fuel pressure. Does fuel pressure drop off after engine is started?
Customer: replied 5 years ago.
do not have a gauge
Expert:  Dave Nova replied 5 years ago.
If you can get or borrow a guage to check the fuel pressure, this will narrow down the problem. If fuel pressure maintains when the engine dies then the security system is at fault. If the fuel pressure drops off, then the engine dies, you may have a faulty oil pressure sending unit. This sending unit supplies power to the fuel pump after starting the engine.

If the security system is the problem and you cannot relearn the system, the passlock sensor in the steering column will likely need to be replaced to fix it.
Customer: replied 5 years ago.
if i end up replacing the passlock sensor will i have to take the truck to a dealer for some kind of programming
Expert:  Dave Nova replied 5 years ago.
No, just do the 10 minute relearn 3 times again and you will be good to go.
Customer: replied 5 years ago.
if i end up replacing the passlock sensor will i need to take the vehicle to a dealer for progamming
Expert:  Dave Nova replied 5 years ago.

No need to go to the dealer for reprogramming. After installation of the pass lock sensor just do the ten minute relearn 3 more times and you will be good to go.

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