I'm in a mess!

A coworker asked me to fix the brake lights on her 01 Jimmy. Sounded easy enough. I took the turn signal assembly loose from the column, sprayed it with electrical parts cleaner (CRC), worked the switch back and forth a few times, and sure enough, the lights started working.

While working on the switch, I noticed the SECURITY light start flashing. Didn't think much of it since I was working with the door open for quite a while. My 00 Sierra would do the same.

Put everything back together and tried to start it. It wouldn't start. So, just like my Sierra does, I locked the doors, waited about ten minutes and tried again. No luck. SECURITY light stayed on. Waited til the next day, SECURITY light still on. Disconnected battery overnight. Light went off. After a couple of cranks, light came back on and will stay on until battery is disconnected.

After really looking things over, I noticed that the dome lights, map lights, rear hatch release, door chime, and rear wiper no longer worked! All fuses are good. Lights will work with a jumper wire in place of the relay, and rear hatch release will work if you touch a test light to the correct terminal on the leads for the BCM. The rear wiper works sometimes, but jumps around whenever hooking up the ground cable to the battery.

Have tried the computer relearn (key on for ten minutes, off five seconds, repeat three times). SECURITY light won't even flash, stays on steady. Any advice would be greatly appreciated. I think I've covered everything I've done and tried, but feel free to ask any questions. I even tried another BCM(numbers matching, of course).

 

When you removed the multifunction switch, did you happen to unplug a small little white plug with two small wires (red and green IIRC)? If the passlock sensor were disconnected, it could cause the no-start and constant security light. If you still have it open, check this plug. Disconnect and reseat it and see if it helps. Sometimes corrosion in the plug can cause passlock issues.

Ignition Switch Replacement by WolfPack will have some pictures showing what I am talking about.

 

can you explain this computer relearn thing and is it good on any gm vehicle ????

 

Works for 98+ as it says in other threads on the subject.

 

Are you talking about the flat white plug immediately above and behind the key switch? This one has three wires. Best I can tell from the pictures we're on the same page. The other plug that twists out is ahead of the key. I checked the plug and the three wires in it just pull out of the plug. I have them pushed back in and no change. For what it's worth I disconnected the battery overnight and will try again today. Other GM posts have indicated changing just the tumbler assembly to changing the entire switch. I think the next thing I will do is replace the entire switch. Please advise. BTW, I read your article "Anatomy of the Ignition Switch" EXCELLENT piece! Is their a possibly that the IGN 1 circuit is connected to the other problems I'm having? Such as the map light, dome light, rear hatch, etc?

 

Can anyone tell me if there are any other components to the security feature on an 01 Blazer other than the ignition switch and key switch? If the BCM is part of it, how do you go about programming a replacement? The thirty minute computer relearn procedure does not work. Is that only for the PCM? Thanks in advance.

 

The PCM & BCM are both part of the system. If the 30minute relearn did not work, then you need to have a forced relearn done with a Tech2 (dealer).

What did you replace that is causing your current problem? If you just replaced the ignition switch, are you sure you plugged in the passlock sensor (small two wire plug)?

 

Thanks for the reply. We had discussed this in more detail last week in my thread titled "Security Mode". Since a week had passed I had decided to post a new thread. If you'll look back at it and get with me I'd really appreciate it.

 

This is the very reason why double posting is prohibited. This is much more appropriate in your previous thread where the history is. I will merge your threads back together.

The ignition switch can cause all kinds of problems as you have already read (and can read even more about through use of the search function).

 

Sorry for the double post, it's just that over the course of a week I had no replies. I'm really between a rock and a hard place and was hoping to get this problem resolved asap.