Security light

[Danneman]

'99 Yukon SLT. 120k miles. No major electrical upgrades or changes, no aftermarket alarm or remote start or anything like that, and no electrical issues outside of the usual OBS small stuff up to this point either - except now I've got my security light popping up on the dash. Every time I drive it, but only once I've put it in gear (and, I think, specifically in drive). (I've started and idled in park for 15 minutes to see if it would come on, and it wouldn't, and within a few seconds of putting in gear, there it is.)

So, starts fine, runs fine, no other issues. I've researched here an elsewhere. The only easy potential fix I ran across was disconnecting the battery (both sides) and leaving it so for 15 minutes, and I tried that, and it worked for my first drive out. Second time, right back where I started from.

Relay? Something else simple? Any thoughts are most appreciated. -D

 

[east302]

I've read where some people have cleaned out the ignition switch (lock cylinder) using a can of compressed air with a straw. The thinking was that the passlock contacts (or whatever is in there) get dirty and cause the issue.

You may also try removing the lock cylinder and seeing if you spot anything. I vaguely remember there being a small electrical connector on it, but don't remember if it was for the Passlock or not.

Otherwise, since it only happens when in gear, there may be a wire being pinched when the shift lever is moved, so opening up the column may be worthwhile.

Here is the diagram from a 98. There should be three wires coming from the sensor at the ignition switch and going to the passlock module...yellow, red/white and orange/black. I believe the module is under the dash somewhere behind the ashtray.





Here are the diagnostics for "Security indicator always on or flashing"...










Sent from my iPhone using Tapatalk

 

[Danneman]

Very helpful! I will try / use all of the above. Much appreciated. Will report back with results.

 

[kbuskill]

Just for the record I had a similar issue with my 2000 Escalade.... It started off with the security light coming on and progressed over time to actually causing starting issues. It would start and then stop immediately because the truck thought it was being stolen. I ended up having to replace the BCM.

 

[Danneman]

I think the compressed air-blowout did it! Hope I'm not jinxing it, but the light hasn't come back on in two days. Many thanks for the suggestions.