2006 Nevada Highway PAtrol Tahoe Security issue?

[CustomCoffinWorks]

My father had his battery died in his Tahoe listed in the description. I replaced it and it started fine, but the idle seems to be surging. I marked this up to the ECM reprograming and thought nothing of it and left. He did drive it one day without mentioning any issues. The next day he couldn't get it to stay running. It would turn on, crank right over but as soon as it started running it would stop and the dash would flash like someone is touching the battery cable on and off the post. I will say that the key he uses is not a PATS key. I have removed the plastic cover looking for a bypass loop that someone may have installed but nothing seems to be out of the normal there ether. If I disconnect the battery and connect it back up, it will do the same thing. Once it has shut off, it will not crank over. I also notice the security light does shut off. I even tried to have the system "Relearn" the key with the left on for 10 minutes for three times...no work. Is it common for a bypass installed on PPV issued Tahoe's? I really want to get his Tahoe back up and running again, but at this point am at a loss.

Thanks everyone.

 

[rockola1971]

The engine is likely running like crap because it has to do an idle relearn and that usually takes 20-50 miles of driving. Is check engine light coming on or flashing when engine does run? With the Security light not turning off that tells me that the security system is not happy. It should have the PASSLOCK security system. There isnt any "chips" or resistors on the key. The PASSLOCK sensor in the ignition lock area is just looking for a metal key. I suspect the relearn procedure was not followed close enough. Directions listed below. If it continues to fail then you may have a Passlock component failed.

1-Turn ON the ignition, with the engine OFF.2-Attempt to start the engine, then release the key to ON (vehicle will not start).3-Observe the SECURITY telltale(this is the security light), 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(TM) Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK). IMPORTANT: The vehicle learns the Passlock(TM) Sensor Data Code and/or password ***** the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle. 6-Start the engine (the vehicle has now learned the Passlock(TM) Sensor Data Code and/or password).

Chain of command for your Passlock system: Key sensor at your ignition lock > BCM > PCM and of course wiring in between which could mean broken wire or blue/green crusties (corrosion) at respective harness plugs.

I have heard of your problem caused by bad key sensor, bad BCM and even corrosion at the pins on a main harness plug at the PCM.

 

[CustomCoffinWorks]

I did try and do the relearn process. The thing is, when I put the key the ignition turn it to start, it'll start then shut off but the security light will also go off. It doesn't take 10 minutes for it to go off. Also when I connected the battery the first time the alarm went off and we had to disable it with the key fob. After this problem popped up of not starting and I had disconnected the battery again, when I reconnected it the alarm did not go off again. I thought that strange too.

 

[rockola1971]

I did try and do the relearn process. The thing is, when I put the key the ignition turn it to start, it'll start then shut off but the security light will also go off. It doesn't take 10 minutes for it to go off. Also when I connected the battery the first time the alarm went off and we had to disable it with the key fob. After this problem popped up of not starting and I had disconnected the battery again, when I reconnected it the alarm did not go off again. I thought that strange too.

I believe the 2006 Passlock version disables fuel injection AND starter. But we have to get on the same terms here. There are 4 positions for the key. OFF then going forward Run and then Engine Crank. All the way backward is Accessory position. Since the engine is cranking over and the security light is turning off, I dont believe this is a PASSLOCK issue. Your symptom of "dash is flashing" which I assume means also the instrument cluster as well leads me to believe you have a dead short causing a huge load on the electrical or that battery is not good. Short could be in your alternator, positive wire rubbed against metal (ground), could even be a factory amplifier.
So first thing I would do is check battery voltage with vehicle shutoff. If its atleast 12.5v or so then I would have someone start the Tahoe up while you are already looking at the battery voltage on a meter and you should see around 13.8v+ with engine running. If you dont then something is pull your voltage down or your alternator is not putting out enough.

 

[rockola1971]

Possibility also of a bad connection of the battery wires at the battery, starter and chassis main ground wire.