04 Envoy Security came on and headlights turned off


Well-Known Member
I searched a bunch of posts about the security light coming on and doing the relearn. But a couple of nights ago, the security light came on and my voltage meter started wildly going up to 14V then down to 0V and back and forth like crazy. I made it home, parked the car, and when I hit the remote to lock the car it beeped 3 times which it never has done before. I went back out later to check it out and no security light. Tonight I'm driving home and the security light comes on and a couple minutes later the headlights and all the dash lights go off. Then they randomly came on and went off all while the security light was on. Parked the car and turned it off. Waited a minute and turned it back on and everything was fine. It was a bit scary to be driving down the road and all the lights go off! Anyone have any ideas what might be going on and what I should start troubleshooting? I appreciate any insights. Thanks, Jim.
A weak battery or poor connection has been known to cause weirdness. Bad grounds too. I would also normally say the ignition switch but it doesn't control the headlights but wouldn't be a bad idea to change it anyway. It's cheap and fairly easy.


Platinum Supporter
Not 100%, but I thought I recall someone on here experiencing something similar along those lines. I believe it may of been due to a bad ground? Ignition switch like @Mooseman stated also causes all sorts of varying symptoms.


Platinum Supporter
Ok I checked the battery and connections to it and all seems well. It drove today with no issues - man, this is so random!
I wouldn't be so sure the issue was just a one time thing, you might end up coming across other oddities soon.

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