our 98 chev, wont start with the ignition key, well it starts and runs for 1 second then shuts off. it has a after market alarm with remote start< that will start the truck 70% of the time and run fine. so yesterday I took the alarm out, still wont start and stay running for more than 1 sec. I have replaced the ignition harness and ignition switch, but still has the same problem. Any one have a idea what this is. Seems to me the factory security system is going into theft mode? thanks

 

This may help. But, the 30 minute Passlock relearn procedure at the bottom is for a 2000 Silverado so it may not apply in your case. It's worth a try anyway.

PROGRAMMING REPLACEMENT PASSLOCK(TM) SENSOR, BCM, OR PCM

IMPORTANT:

• The body control module (BCM) must be programmed with the proper RPO configurations before performing learn procedures. See BCM Programming/RPO Configuration.
• If replacing the BCM with a GM Service Parts Operations (SPO) replacement part, the module will learn passlock(TM) sensor data code immediately. The existing PCM however, must learn the new fuel continue password when the BCM is replaced.
• If replacing a PCM with a GM Service Parts Operations (SPO) replacement part, after programming, these modules will learn the incoming fuel continue password immediately upon receipt of a password message. Once a password message is received, and a password is learned, a learn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the other vehicle's fuel continue password and will require a learn procedure after programming to learn the current vehicle's password.

Conditions
Use this procedure after replacing:

• Passlock(TM) Sensor
• BCM
• PCM

30 Minute Re-Learn Procedure

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, 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 on 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).
7. With a scan tool, clear any DTCs if needed (history DTCs will self clear after 100 ignition cycles).

 

My '98 did the same thing when I was working on the ignition cylinder. Did you replace the ignition cylinder? If so, you also have to transfer the anti-theft magnet to the new cylinder (if it didn't come with one). My new cylinder did not have the magnet and I couldn't figure out how to remove it from the old one. Also tried to start it without plugging in all the connectors and it wouldn't stay running.

Maybe you can offer me some advice on changing the ignition switch? Mine needs one too but I haven't found a detailed explanation on how to do it. Did you have to remove the steering wheel?

 

I left the wheel on and the shaft hooked up, you just need a reverse torqs socket, 1/4 or smaller. and some time

 

Thanks 2bfeard.

Any progress on yours?

 

You have a passlock bypass on it if you had the remote start. A lot of time the way those are hooked up will cause the truck to go into theft mode. I would take it to where you had the remote start put on at. But a trick for when it doesnt start is leave the key in the ignition on off position for ten minutes it will reset the theft mode most of the time. My truck has the same problem I havent fixed it yet.

 

still wont start, need help..... Gregg

 

OK< just replaced the theft control module under the dash, just below the stereo 3x4 in size. then did the relearn for passlock. We now have a truck that runs. thanks

 

That's great glad you got it fixed!

 

i was having the problems like everyone, and spent hours on-line trying to find everything that i could about the problem, i replaced chip, key, and wiring, at long last i pulled the theft deterrent module, and opened the box and looked inside, i saw a burn mark i knew that was bad, at last i found my problem, lol. and then learned the dealer did not sale them anymore, called acdelco the maker. and they no longer make them either, so, ok, i went to 5 junk yards, and pulled a lot of them from junk cars, and found everyone of them had the burn mark too. and then on my last leg, got to thinking on how to stop the module from arcing, and i tried pumpers glue on the burn spot to stop it from arcing. that was this past wed., and it is still starting and i'm driving my truck, i have no idea of for how long. but it is working now, and now i guess i've got find a computer geek to make a new one becouse they no longer have any of the theft deterrent module 16264955.