Engine Won't Start - Security Light Flashing - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 02-16-2010, 01:52 PM
Deadeye37 Deadeye37 is offline
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2006 Chevy TrailBlazer LS
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Engine Won't Start - Security Light Flashing

I searched the forums and couldn't find anything on this. I was hoping someone could point me in a direction on how to get this fixed.

A couple of weeks ago, this started happening:

If I've been driving around and come home, turn off my car, and after a few moments try to turn the car back on again (say I forgot something and I need to leave again), my engine will turn over, but it won't start. On the instrument panel, the security light is flashing and the engine light is on. No matter how much I turn over the engine/pump the gas, the car won't actually start. I even hit the unlock button my keychain, but that doesn't get the security light to go away. If I wait for 10 minutes, the car starts just fine and drives just fine.

There are no indicators lit while I'm driving around. This only happens when I've been driving, turn off my car and turn my car back on a few moments later.

When my car is doing this, if I turn the car completely off and then turn the key so that all the indicator lights turn on so that I'm ready to start the car, the security light will start flashing.

Please let me know what I can look at to fix this issue. Thank You!
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  #2  
Old 02-16-2010, 01:58 PM
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the roadie the roadie is offline
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2004 GMC Envoy SLT "Roadiemobile"
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The security issue is involved with the key cylinder passlock system. It might have a fault in the wiring, in which case a dealer visit might be necessary. Or you might bring it back to life with a relearning procedure:

30 Minute Learn Procedure (requires no tools)
1) Turn ON the ignition, with the engine OFF.
2) Attempt to start the engine, then release the key to ON. (engine will not start)
3) Observe the Security telltale, after approximately 10 minutes the telltale will turn OFF.
4) Turn OFF the ignition, and wait 5 seconds.
5) Repeat steps 1 through 4 two more times for a total of 3 cycles (30 minutes). The vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.

IMPORTANT: The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

In other words, don't forget the final step 4 before you try to start the car.

6) Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password.
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  #3  
Old 02-16-2010, 02:19 PM
Deadeye37 Deadeye37 is offline
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Quote:
Originally Posted by the roadie View Post
IMPORTANT: The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
Does every '06 trailblazer have a Passlock Sensor that is kept on the key? I have the LE edition with a regular key and a seperate fob that has the unlock/lock and horn buttons.

BTW, thank you for the quick reply
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Old 02-16-2010, 02:26 PM
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the roadie the roadie is offline
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The passlock system is built into the vehicle's key cylinder, so the keys aren't anything special or expensive to have made. The "special key" sort of system is called Passkey. We don't have that.
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  #5  
Old 02-16-2010, 04:07 PM
Deadeye37 Deadeye37 is offline
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During steps 1-5, is the engine not supposed to start?
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  #6  
Old 02-16-2010, 04:47 PM
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TB_n00b TB_n00b is offline
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Nope, so if the vehicle is starting, you should wait until the issue pops up again.
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  #7  
Old 02-16-2010, 05:19 PM
Deadeye37 Deadeye37 is offline
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My car will start after I let it sit for 10 minutes from when the security light first starts flashing.
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  #8  
Old 02-16-2010, 05:32 PM
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attwireless1226 attwireless1226 is offline
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Quote:
Originally Posted by Deadeye37 View Post
My car will start after I let it sit for 10 minutes from when the security light first starts flashing.
Then do that security relearn as The Roadie posted above
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  #9  
Old 02-17-2010, 09:34 AM
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TB_n00b TB_n00b is offline
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Quote:
Originally Posted by Deadeye37 View Post
My car will start after I let it sit for 10 minutes from when the security light first starts flashing.
Do you leave the key in the ignition in the 'run' position for those 10 minutes or do you have the key in the 'off' position or out of the ignition altogther?

Follow the process posted by Roadie as soon as the 'won't start' problem reseurfaces. Follow it to the T.
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  #10  
Old 09-19-2010, 11:05 PM
02TRLBLZR 02TRLBLZR is offline
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What if the security light on the dash NEVER goes out? I am having a similar issue with an '04 LT at the moment.

Backed truck out of driveway and left key on while I finished yardwork (about two-three hours). When I got back to pull into driveway, dead battery. Charged battery and attempted to start, nothing. More specifically, EVERYTHING works, A/C, radio, lights, you name it. Turn key to start=nothing...no clicking of relays, no cranking, no nothing. Release key to on=security light comes on and remains lit for 10-15-20-25 minutes...never goes out.

Considering driving off a cliff.
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