Bypass Passlock II on 05 Tahoe

[ReconRooster]

I recently bought an 05 Tahoe, with no keys, as they were lost by the former owner. They also beat the ignition lock cylinder so badly with a hammer and screwdriver, that it was unuseable.
I replaced the damaged original with a Locksmart cylinder made specifically for my year model Tahoe. However after installing, it still won't start. I had decoded the VIN, and found it's equipped with the Passlock II system, I've tried the relearn, the bypass, still can't get it to start, and it's not displaying any security lighting on the Dash, as far as protection engaging. Anyone have any ideas at all? Thanks

 

[Doubeleive]

so if you mean by no start that the starter will not engage, then try jumpering the starter relay and see if the starter works, if the starter does not move then be sure it has at least 10.5v minimum (at the starter) with the key in the start position, if it has 10.5v or more then smack it with a hammer a couple times and see if it starts working. at that point if it has 10.5v or more and does or does not work after hitting with a hammer then-replace starter, if it does not have at least 10.5v to starter check battery or replace starter cable.
if all of the above checks out then try starting it in neutral and/or check neutral safety switch or shift interlock

if you mean the starter engages but the engine will not run then check fuel pressure, with the key in the run position you should have anywhere from 50-65psi
if not then it may be a possible fuel pump issue, if there is pressure but then looses all pressure when trying to start then it's possibly a security issue or bad fuel pump.

in either case test the battery to be sure it has 12v and can hold a load and still have 12v, like headlights on, rolling a window up/down etc and still have at least 10.5v minimum.
if not charge or replace battery.

the above is likely not everything to check but should point you in the right direction.

 

[ReconRooster]

My apologies, the engine will turn over, start for 1-2 seconds, then die. The battery, starter, and alternator all check 100%. I'm not getting a light about the security system at all on the Dash panel, so I'm kind of at a loss at this point.

 

[Doubeleive]

My apologies, the engine will turn over, start for 1-2 seconds, then die. The battery, starter, and alternator all check 100%. I'm not getting a light about the security system at all on the Dash panel, so I'm kind of at a loss at this point.

The security light should illuminate when you turn the key to run for about a second or two then go out, if it is not doing that then there is issue with the cluster or passlock system, if the security light is not lighting up at all then I would start checking fuses first. All fuses because GM likes to tie things together and not saying anything about it. The GM upfitter guide may show all the fuses related to the security system. you may end up needing a scanner like a tech2 or comparable scanner that can read bcm codes if there are no outward signs of why it is shutting off.
other possibilities could be bad fuel pump or fuel pump control module, but I would try to rule the security system out before diving into that because what you are describing is exactly what it does if the security system is engaged or not working properly it commands the fuel pump off.

 

[energizedtech]

Probably not the same thing but that's exactly what happened in my 2006 Suburban after the dealer fried the BCM. I had a spare in the back that was supposed to be bad to see what would work and it turned out to be fine.

But yes, I relearned the security, no security light and 2 seconds "Battery not charging" plus a host of other things like the lights only turning on if the key was on in the ignition, Powerlocks didn't work, PowerWindows didn't work.

Swap in BCM with proper VIN, all worked

 

[ReconRooster]

The security light should illuminate when you turn the key to run for about a second or two then go out, if it is not doing that then there is issue with the cluster or passlock system, if the security light is not lighting up at all then I would start checking fuses first. All fuses because GM likes to tie things together and not saying anything about it. The GM upfitter guide may show all the fuses related to the security system. you may end up needing a scanner like a tech2 or comparable scanner that can read bcm codes if there are no outward signs of why it is shutting off.
other possibilities could be bad fuel pump or fuel pump control module, but I would try to rule the security system out before diving into that because what you are describing is exactly what it does if the security system is engaged or not working properly it commands the fuel pump off.

Yes sir, it's throwing a P1626 code, but no security light.

 

[Fless]

I would suggest seeing if an advanced scanner could look at the BCM communication. Check the BCM fuse first, and the voltage on both sides of the fuse.

 

[Doubeleive]

Yes sir, it's throwing a P1626 code, but no security light.

either something is wrong with the ignition harness or the ignition you purchased is no good
p1626

• Faulty ignition switch
• Ignition switch harness is open or shorted
• ignition switch circuit poor electrical connection
• Incorrect ignition key