It's probably related to installing the cruise control turn signal stalk and wiring harness, or the CD player radio. I got both from a 1999 GMT 800. Some of the contacts in the stalk were corroded, I saw them because I had to trade my 4-way switch into the 1999 control because it was broken. I am not sure about the contacts in the two wire plug that goes to the ignition tumbler.
The issue is that the message center randomly blinds me with the SECURITY message even though VATS has been disabled in my tune since forever. And it only just recently started, six weeks after I installed cruise and swapped the radio.
Any ideas?

 

My 1500 99 also has VATS disabled and the "security" in the message center flashes just as it did before disabling it.

So your truck is a 2000 model and the Multifunction Switch was replaced from a 1999 truck? The corrosion in the connectors surely does need to be cleaned. Apply dielectric grease to keep moisture out.

I'm looking for a wiring diagram for that Security light circuit, but can't seem to find one on-line for free. I think the generic Haynes manual may have. I can check when I get home.

 

I have a shop manual, let me look it up for you

 

 

That's for 2000, I wouldn't know if they made any changes from 1999

 

You could always remove the security bulb...

 

Um, so the cluster does tie into the cruise control circuit:


But I think that may be for the "cruise" dash light to come on when you set it. Did your cruise control work before you changed your Multi-Function Switch? 1999 vs 2000 may be worth looking at for differences, but probably none.

I wonder what those tamper/security sensors are on the first sheet? You sure your truck hasn't been tried to tampered with? Maybe there's an issue with the BCM?

 

I had to change my tune to activate cruise, and there is a "cruise" light in the cluster. I didn't have cruise before. The only security in my base model truck is VATS. I just noticed that the passlock sensor on the first page, has three wires. Now I think that this is the wrong diagram because there are only two wires going to my ignition tumbler

 

I haven't seen the SECURITY message since maybe 2004, and it doesn't affect anything, it just shows the message. Another clue is that VATS shows the security message and keeps the engine from starting. In this case, the security message will come on when I'm driving and either go away, or be gone on the next restart.

 

I read a little (ouch!) and the sensors are two hall effect sensors in the column. The diagnostics tree leads to any of these: bad passlock sensor, BCM, or cluster. This would be a great excuse to get a Denali cluster.