Starts and immediately dies....

[Merc1973]

My 2003 5.3 flex fuel with 333,300 miles has recently had Pass Lock security light turn on randomly while driving. It does not affect the engine at all. There have also been some other electrical issues lately. The drivers seat does not move nor does the horn function now, All fuses passed with multimeter. However a month ago, the day after replacing the fuel pump with a Delphi unit from RockAuto, upon a cold start it would run for a second then die. Attempted many times and did the same. Security pass lock light was on (nor sure if it was flashing). Came back 1 hr. Later snd started just perfect, no problems. Security still randomly turns in off while driving every day. Decided to check grounds... I cleaned the BCM ground under drivers side frame rail and briefly inspected the 2 small grounds at the back of the engine block, wires were not broken. No change.

Fast forward tonight, after work it did the same thing (cool rainy night) . Pass Lock security light was flashing. I Waited 15-20 minutes it started just fine and was able to drive home. Security did not turn on, nor were any others lit. Ran great.

I don't have a scan tool or fuel pressure guage so i can't confrim if its fuel or anti-theft issue. Anyone else have this issue? Ill work on getting a fuel pressure guage

 

[strutaeng]

Do you have a test light? The VATS (i guess that's the same as passlock?) will kill both injector pulse and spark (and also kills the fuel pump).

A test light on one injector along with a spark tester on a spark plug while a helper cranks will probably reveal it's the VATS system. "Fire and immediately dying" is a classic security system trigger...

Do you have have any "tuners" in your area? They can disable that via HP Tuners or similar software

 

[Merc1973]

Do you have a test light? The VATS (i guess that's the same as passlock?) will kill both injector pulse and spark (and also kills the fuel pump).

A test light on one injector along with a spark tester on a spark plug while a helper cranks will probably reveal it's the VATS system. "Fire and immediately dying" is a classic security system trigger...

Do you have have any "tuners" in your area? They can disable that via HP Tuners or similar software

Thanks for conformation. I was looking here to bypass the Passlock/VATS.

GM Passlock Security Fix

Looks like i can also send my PCM to Black Bear

Permanently Disable GM Passlock System

The GM Passlock system was introduced by GM on the 1986 Corvette because the Corvette had become the number one target of car thieves. Corvette thefts dropped so impressively after VATS (Vehicle Anti-Theft System) was implemented that GM expanded the system in 1988 to the Camaro, Firebird, and...

www.blackbearperformance.com

Also South Main Auto has a video

 

[rockola1971]

To decipher this circus you need to understand that PASSLOCK is not a module in itself but a collection of 3 modules and one sensor. The sensor in the ignition lock cylinder area is just looking for a metal key thats it. Once it sees one the BCM is allowed to see a resistance that is in series with the sensor and the BCM. The BCM has to have this resistance value stored because it is essentially a password used by the BCM to check for security. Once a valid resistance is given to the BCM it then refuses to send the PCM the kill the engine signal which is kill the fuel pump relay signal. If an invalid resistance is seen by the BCM then it will kill the engine between 5-10 seconds after it is started. When you have to program your passlock because of an ignition module or BCM change, this resistance is what you are programming.

 

[Merc1973]

Thanks for the explanation. Thats what ive read too. I have utilized the 2.2k Ohm resistor method. It does start as it should, however the Passlock light stays in all the time. In might try to check the resistance and use appropriate resistor like the South Main Auto video or just send the PCM off to Blackbear.

 

[rockola1971]

Thanks for the explanation. Thats what ive read too. I have utilized the 2.2k Ohm resistor method. It does start as it should, however the Passlock light stays in all the time. In might try to check the resistance and use appropriate resistor like the South Main Auto video or just send the PCM off to Blackbear.

When the security light is lit that just means the system is on (it should not be on if vehicle is running). Its when the security light is flashing is when the "alarm is going off" and in that case proper operation would be it shuts engine off in 5-10 secs after the first flash.

Essentially the BCM is the brain of the Passlock system. It is what triggers the security light on, off or flashing.

 

[Merc1973]

When the security light is lit that just means the system is on (it should not be on if vehicle is running). Its when the security light is flashing is when the "alarm is going off" and in that case proper operation would be it shuts engine off in 5-10 secs after the first flash.

Essentially the BCM is the brain of the Passlock system. It is what triggers the security light on, off or flashing.

The only time it flashed is when it would start and shut off after 1-2 seconds. Prior to resistor the light would randomly turn on and pff while.driving. Perhaps I'll look into a replacement BCM.

 

[rockola1971]

The only time it flashed is when it would start and shut off after 1-2 seconds. Prior to resistor the light would randomly turn on and pff while.driving. Perhaps I'll look into a replacement BCM.

Replacement has to be flashed to your VIN and PASSLOCK relearn must be performed.