Security system issues

You have an issue with the Passlock immobilizer. It requires a Tech2 scan tool to be able to diagnose these but one of the more common problems is the sensor in the ignition switch messing up. I'm giving you the relearn procedure that may or may not work. If it doesn't or if it happens frequently, you will have to get it diagnosed properly.

This guide can help

https://www.2carpros.com/articles/how-to-reset-a-security-system

PASSLOCK 10 MINUTE RELEARN


AUTO LEARN
Time required, approximately 10 minutes:

1. Insure that the battery is fully charged.
2. Use the scan tool in order to clear the DTCs.
3. Turn the ignition switch from the OFF position to the CRANK position attempting to start the vehicle. The vehicle will start and then stall.
4. Leave the ignition switch in the ON position while observing the security indicator.
5. When the security indicator turns off, which can take up to 10 minutes, turn the ignition switch off. Wait 10 seconds.
6. The BCM and the PCM will learn the new code on the next start attempt.

Hello. I have the stated truck. The "Security" message came on while driving the other day. When I turned off the truck and started it, the message went off. This happens periodically, but not all the time. It can go days without coming on. Any ideas? Thanks.

you may have to stop somewhere and have it scanned for trouble codes. when you do, get back to me with the codes and ill see what i can do to help

[quote:38b115b6ad="rhall77"]you may have to stop somewhere and have it scanned for trouble codes. when you do, get back to me with the codes and ill see what i can do to help[/quote:38b115b6ad]

Thanks. Will do.

So I need some help. When I bought it, it did not come with the key fob. Got one online and would not program. Been dealing with this for a year now. Went out today and got a new key-less entry module with two fobs. Still will not program! I'm doing the usual hold down unlock on drivers door, turn key on off on off and it goes into program mode. That's where it ends. I also checked the fuse and it's good. Am I missing something? Help!

Hi,

Just so I am clear, you are able to enter the programming mode and it cycles the locks only once to indicate this or does it cycle the locks more than once? If only once, when you hold down the lock and unlock on the fob for 15 seconds, it doesn't cycle the locks again?

If this is the case, we need to scan the BCM to see if there are codes. More than likely you have something in the BCM that is preventing it from completing the process and if so, there should a code to give us a clue. Let me know what that is if there are codes and we can go from there.

Yes, when entering the programming mode the locks cycle only once. After it cycles, I hold the lock and unlock on the fob for at least 15 seconds to 1 minute and nothing happens. One thing I did notice is when I start driving, my seat belt light flashes for about a min then goes out even though I have my seat belt on. I'm not sure if that has anything to do with it.

Okay. If it doesn't enter programming mode then the BCM is most likely the issue. When it does enter but fob's don't respond the the receiver module is usually the issue. Basically you are turning the key and the BCM sees that you are doing this and enters the mode. Then you press the FOB buttons and the receiver module is responsible for receiving the signal and sending it to the BCM. It never picks it up so more than likely it is the issue.

It is located in the center of the dash. Pictures attached.

I just replaced the receiver module and it still will not program.

For the past 4 years I have been dealing with the factory alarm for which I don' t have a keyless entry transmitter. I often have the problem where the engine fires up then automatically triggers the kill switch to which I have to wait anywhere from 15-45 minuetes before the truck starts. I have contacted the dealer and there answer to the problem is......"..reprogram the alarm system for a fee of about $500 -700 dollars". With this economy I just don' t have the funds to do it right now. Is there anything I can do to disconnect or bypass this problem. Please help.

hey joe i see you have the same problem as mine, only i have been trying to solve this alarm issue thing for over 4 years now, with no direct answers as of today, if i run across a good solution to our problem i will be sure to post the answer so you can get on with your life. really now i'm looking at purchasing a new alarm from J. C. Whitney called a Valiant, the item number is 1JA478507, however i too don't have a lot of free cash, so i'm looking for this product at a better price that what J.C. Whitney wants? more if and when i find something.

Unfortunately, I suspect the only thing left is the BCM.

Okay. Can I get a BCM from a junk car (same year and model vehicle as mine) and put it in my truck?

Yes. I would just pull yours out or at least see if there is a part number on it and get the same one. Just same model and year will not be enough to be sure they are equipped the same.

Awesome. Thank you so much for your help! If I have any more questions I'll let you know.

Sounds great. Thanks

Electrical problem
1999 Chevy Silverado 6 cyl Two Wheel Drive Automatic

this truck was stolen and the sterring wheel had to be replaced
also i replaced the fuel pump and fuel filter
i also put a new battery into this truck
it starts and stops right away and if you try to hard to keep turning it over to start i wont fire again untill you let it recycle the computer
the truck was towed
my question is how do i get this thing to start and stay running

Try to start the engine. Release the key back to the "RUN" position and let it sit for 10 minutes. Turn the key OFF. Turn it back on to RUN and let it sit again. Do this 3 times. Then try to start it. This should reset the security system. Just to be on the safe side, though call your local dealer and double check me on the times. I've dealt with several of these and I may get the procedures confused. I don't want to give you incorrect info so double check me.

Security keeps coming on & the truck will not start. We have tried to reset many times. The security light will go off; but as soon as we try to start the truck; the light will come back on & the truck will not start. We have replaced the security module & there is not a chip in the key. Is there something else that would cause this issue?

First, are you sure of the engine size? I'm not showing a 5.7L for this vehicle.

Also, everything I show says the key should be chip in the key. There is a hall effect sensor that determines if the key is correct when you turn it.

Listen, I need you to have the computer scanned to see if there are trouble codes. I have system checks, but I have no idea where to look for your type of problem.

i replaced the engine in my 1998 silverado in 2010. since that time about once a month when you go to start , it will hit for a couple of seconds then die. my son said it had to do with security system problem. after you wait approx 12 mins it starts fine until the next time.

When this happens, is the security light staying on? When you wait 12 minutes, do you leave the key off or on? Have you ever checked fuel pump pressure when this happens?

security light is on and key is off. like i said sometimes goes a month sometimes a couple of weeks thanks very much for ur interest

no i have not checked fuel pressure

We changed the entire steering column in the truck. It now won't start. The security light comes on. The car starts but immediatly dies.
We tried the "re-learn" procedure that instructs you to leave the car on for 10 minutes, then off for 30 sec., doing that threee times in a row. Still not starting. Cleared the codes with the scanner, tried the relearn procedure again, still nothing happening.
The security light still flashes when trying to start and the car immediatly dies...At this point not sure what to do or try...should I be calling a locksmith?

1-If Tech 2 scan tool is not being used, go to next step.

2-NOTE:While VCM is in Auto Learn Procedure, battery voltage must be maintained at all time. This procedure must be followed exactly or procedure will have to be repeated from beginning. Performing following procedures will set DTC P1630. Turn ignition off for 30 seconds, then turn ignition on. DTC P1630 should clear. If it does not, diagnose DTC P1630.

3-Turn ignition on, with engine off for 11 minutes. Turn ignition off for 30 seconds. Repeat turning on ignition for 11 minutes, and turning it off for 30 seconds 2 times. Turn ignition on, with engine off and wait 30 seconds. Attempt to start engine. If engine starts and operates normally, go to step 4). If engine does not start or operate normally ,go to step 5)

4- Using scan tool, clear VCM DTCs. Turn ignition off for 30 seconds. Attempt to start engine. If engine starts and operates normally, system is okay. If engine does not start and run, go to next step.

5-Using scan tool, read DTCs. If DTC P1626 or P1630 is set, diagnose affected DTC(s). If DTC P1631 resets, return to step 2).

,I changed my ignition housing due to lock cylinder damage,chevy 98 k3500,now it wont start,security light blinks in dash

The key will need to be coded the dealer can do it for you if you give them the VIN when you buy the key from them. You can try resetting the system by following this guide.

https://www.2carpros.com/articles/how-to-reset-a-security-system

Please run down this guide and report back.

Scan the computer for a passlock code/s -start here and let me know if there's any present-

Thanks for this post I had this issue and had the key codes at the dealer when I bought it worked perfect FYI.

Truck won't run starts quick imediatley shuts off. Then will start quickly again but won't come to a full idle. Put in new spark plugs drained gasoline out replaced with new.Pulled gas filter appears clean.

That sounds like the passlock theft system. That's an injector disable. Is the theft lite flashing, or anything? If the theft lite is flashing, wait till it stops flashing, then try to start.

Computer problem
1999 Chevy Silverado V8 Two Wheel Drive Manual

Security light comes on when you turn on ignition. Truck will turn over and will start but immediately goes dead.

Was told this is something to do with a manufacturer security install in 1999 and this was the only year they did install this.

I'm giving you the relearn procedure. It may or may not work. If it doesn't, that would mean it has a hard failure and will require using a Tech2 scan tool to diagnose it.

Disconnect the battery and hold the cables together for about 30 seconds then reconnect the cables before performing the procedure.Read it carefully if done incorrectly it won't work.If it helps let me know.
Turn ON the ignition, with the engine OFF.
Attempt to start the engine, then release the key to ON (vehicle will not start).
Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
Turn OFF the ignition, and wait 5 seconds.
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes (the vehicle is now ready to relearn the Passlockâ„¢ Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK).
Important
The vehicle learns the Passlockâ„¢ 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.
Start the engine (the vehicle has now learned the Passlockâ„¢ Sensor Data Code and/or password).
With a scan tool, clear any DTCs if needed (history DTCs will self clear after 100 ignition cycles).

Will start sometimes and won't sometimes. Security light flashes. Will start times in Neutral and runs fine when it starts. Will be OK for a couple of days. Then will not start. Motor turns overs and fires but immediately goes dead. Someone suggested neutral safety switch. ??? Any suggestions?

When it does not start, does the engine crank?

Yes, engine starts but immediately goes dead. I read something about the security system could be causing this. Motor fires and cranks but system immediately shuts doen the fuel pump. This is what is acts like.

Need to bypass the security code. I have lost my keys in my truck will not crank because of security system.

Welcome to 2CarPros.

The easiest and really only real solution would be to get new keys made by either an automotive locksmith or go to a dealer and give them your VIN along with proof of ownership and ID. They can then cut new keys using the code from GM. The locksmith option is probably cheaper and they will come to you.