1998 chevy lumina

The unlock code for the radio in each vehicle differs from each van. You will have to go to a dealer to get your specific code by means of using you v.i.n. I think that is the answer that you are looking for.
If it isn't and you just need an explanation what an unlock code is, when you loose power and reconnect power, the anti-theft is engaged. There for you loose your functions on the radio. To reprogram it you will need your unlock code to do so.
Hope this helps.

You will need to go in to the Chevrolet dealer to retrieve the code needed they might charge a small fee not certain.Once you have completed this you will have a unlock code in your possession.

Call the dealer give them your vin number.

Call the parts depts at your local chevy dealers. With a 12 year old car a nice parts guy will usually give you the code for free. Look up how to pull the radio code up on the internet (you have to hold down certain buttons on different theft-loc radios). Give the numbers to the parts guy and they will call in and get you the unlock code. Otherwise they charge you to get the number...good luck

here are two definitions.
First: ignition coil module 4 times ref circuit intermittent no pulses.
Second: Distributorless ignition system 4 times signal interrupted.
You will want to inspect the spark-plugs, spark-plug boots, Coils for defects. Let me know how it goes.

Unlocking the system from the manual.
1. Turn on ignition. LOC will appear.
2. Press MN and '000' will appear.
3. Press MN again and hold until you see the last 2 digits of your code.
4. Press and hold HR until you see the first 1 or 2 digits of your code.
5. Press AM FM after you make sure the code is correct. SEC should appear, meaning your system is ready and still secure. If LOC appears, the code was wrong. Good luck

dealer only can give them codes

if you do not have the code.gm will do it for 40 dollars.

I've heard of people using Delco Lock Codes (http://www.delcolockcodes.com) to get their radios unlocked. They seems like a legit site from what I've read. Good luck!!

Search the net for "Delco unlock codes" OR "Delco security codes" you should easily find a set of instructions telling you to get a code from your radio and then call an 800 number. Follow these instructions. This will give you the factory unlock code for your stereo. Worked for me and for heaven sakes don't pay anybody for this information - it's free.