That makes sense, if your ignition has "learned" your security resistor the BCM is the component that verifies that and allows the ECM to start and run the engine; if the BCM is not passing on the all clear the ECM will not let the engine start.
No start issues again
- Thread starter Phisher
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rockola1971
Full Access Member
If that were the case then the the security light would be flashing and the engine would start up and almost immediately die. Its been decades since GM vehicles had a ECM. They have a PCM, not ECM.
rockola1971
Full Access Member
That resistance range is in the lock cylinder module, not the key like old school GM from the 80's.(My 85 vette has it) By your logic anything that has to do with the engine that is electronic is an "ECM". An ECM is an Engine Control Module. Again GM hasnt called any module an ECM for decades.
I never said the resistor was in the key, from my first post I said it was in the tumbler housing.
No, not everything that has to do with the engine is an ECM, but every Module that Controls the Engine is an ECM. If it also controls the Transmission it is also a TCM; if it controls both it functions as a PCM.
There is nothing incorrect about referring to the unit as an ECM when the engine control functions are being diagnosed because it IS the "Engine Control Module".
Your attempt to make an issue about that is like someone derailing a thread because the term "motor mount" was used and "motors are electric" ; it doesn't make you sound smart especially after you claimed in error that a 2004 Tahoe doesn't have a VATS system or a resistor that controls it.
The OP needs help and you don't know enough to help him but you are choosing to pollute the thread with error and meaningless distinctions; some of us are trying to help him get his car running.
rockola1971
Full Access Member
You just got done saying "If it controls both it functions as a PCM". The PCM in our year range is neither a ECM nor a TCM. GM didnt start splitting up the PCM into 2 separate modules (ECM and TCM) until 2007 model year. And GM never put the VATS system in our generation of C and K chassis. The VATS system was used in the mid 80's to mid/late 90's depending on model vehicle and production year and then ENDED and REPLACED with the PASSLOCK I, II and III system. They are NOT the same and do NOT work the same either. You using the term VATS is nothing but incorrect. Are you trying to get the OP to look up and troubleshoot an ECM and VATS system that isnt even in his 2002 vehicle? You using VATS as a generic term for ALL GM security systems is also incorrect if that is what you are doing. He has a PASSLOCK II system in his 2002 vehicle.
MassHoe04
Full Access Member
I'll just throw one of my recent experiences out there, just in case it helps anyone at all... Maybe it won't help, but here is what happened.
Late last year, I hop in, turn the key to start and nothing. No click. No crank. No start.
Try again and it starts.
Happens intermittently, but always started. I was thinking Passlock II was beginning to fail.
Sometimes a second turn of the key would not work. I thought maybe a bad contact in the door latch was somehow interfering with the security system, telling it was locked or unlocked when it should be. So, I would open and slam the door closed, then cycle the lock/unlock on the power door locks. Sometimes it would start first try after that weird Rainman procedure.
Then, the door/lock/unlock process did not work a few times. Just the ignition switch after waiting a few minutes. It would always start at some point.
Still thinking I should go out and buy a Passlock II ignition sensor module.
Then, nothing I tried would work. I was dead in the water.
Yeah... It was my starter the whole time.
Replaced with new. Never had the no-crank/no-start come back.
I am glad I didn't drop money on a new Passlock II module. Had nothing to do with my problem.
Like I said... It may be a long shot, but I just wanted people to know that what I thought was a more complex problem intertwined with my Passlock II and security system was really just a simple problem of starter failure.
Late last year, I hop in, turn the key to start and nothing. No click. No crank. No start.
Try again and it starts.
Happens intermittently, but always started. I was thinking Passlock II was beginning to fail.
Sometimes a second turn of the key would not work. I thought maybe a bad contact in the door latch was somehow interfering with the security system, telling it was locked or unlocked when it should be. So, I would open and slam the door closed, then cycle the lock/unlock on the power door locks. Sometimes it would start first try after that weird Rainman procedure.
Then, the door/lock/unlock process did not work a few times. Just the ignition switch after waiting a few minutes. It would always start at some point.
Still thinking I should go out and buy a Passlock II ignition sensor module.
Then, nothing I tried would work. I was dead in the water.
Yeah... It was my starter the whole time.
Replaced with new. Never had the no-crank/no-start come back.
I am glad I didn't drop money on a new Passlock II module. Had nothing to do with my problem.
Like I said... It may be a long shot, but I just wanted people to know that what I thought was a more complex problem intertwined with my Passlock II and security system was really just a simple problem of starter failure.
rockola1971
Full Access Member
The Passlock 1,2,3 do NOT prevent an engine from being cranked over and started. The security system allows the vehicle to be started and then shuts it down within seconds if the Passlock security checks are not met. The very old system (VATS) used an actual resistor on the key (incorrectly called a chip) and was designed to prevent the vehicle from being srated at all and stolen if the wrong key was used or the ignition was popped with a screwdriver. The Passlock system is triggered by ANY key that unlocks the ignition lock which allows vehicle to be started. So If I had a copy of your key, I could steal your vehicle. But if a screwdriver or similar tool was used to break the ignition lock which allows it to be turned forward then the vehicle would start and run for a few seconds and shutdown because the key is not inserted activating the magnet system in the passlock device integrated into the ignition lock. The magnets have to be moved by the metal key and that triggers an electornic switch which sends a resistive signal (most likely derived to a current type signal or possibly voltage drop precise voltage range) which is being looked for by the BCM. The BCM then has to send over a permissive signal to the PCM to allow engine to continue running after a set amount of seconds.
Fun system to have fail while you are driving down the highway at night at 70mph and a semi to the right of you and one behind you! Fun times!
MassHoe04
Full Access Member
Thanks for that overview!
