Hello. I have a 2000 Blazer LT. For the longest time I have had this problem but have just been lazy and dealt with it up untill now.

What happens is sometimes when I turn the ignition off the headlights will turn off with the vehicle but then come right back on, a long with the HVAC fan, if it is still turned on. The lights on the mirror "onstar mirror" will flicker as well as the climate control lights. But 9 times out of 10 it behaves normal.

Right around the same time my 4wd stopped working for no apparent reason. The buttons on the switch wont even light up but luckily it is stuck in 2WD for now.

I have researched this quite a bit and find it to be a very unique problem. I have reset the ECU. Cleaned the battery terminals "worth a shot", checked all of the fuses, and checked for any noticeable shorts in the ignition system.

I should also mention that I had a remote starter/keyless entry installed professionally prior to this, but had no issues for about 6 months. I unhooked the remote starter system but still no luck.

Any help would be greatly appreciated!

Thanks in advance,

Jordan

 

A possibility is when they installed the remote starter the wires are arced between a battery feed and one of the accessory outputs or your remote starter is shorted internally. If you unplugged the remote starter and it does the same thing this is unlikely though. My vote goes to your ignition switch went bad.

 

Thanks for the tip and reply RonJon, Are any of my symptoms similar to others with a bad ignition switch?

 

Im going to suggest looking at all the grounds.

 

the gm vehicle have a bcm that controls stuff like that and the ecm controls the motor.
i just had to replace one on my wifes buick not sure if the 2000 blazer has one or not but i am sure i will find out soon since i am having problems with my 2000 blazer.

 

The 2000 blazer definitely has a BCM and his remote start probably tapped into some of the wires (I know mine does). It's located under the heater box above the front edge of the center console. I blamed his ignition switch as a possibility but the BCM is another one. That controls the Retained Accessory Power (RAP) so when turn your key off the windows, radio, and other things work until you open the door. That being said, not the headlights, they don't stay on with RAP (speaking from my own vehicle). Also if it was your remote start/alarm, if it's similar to mine and operating correctly, stepping on the brake pedal (with the key off) would shut everything off. Most of the time people have to replace the ignition switch because the arm(s) got hot and distorted and no longer make a good contact with the key turned on. I figured maybe you have one that's still barely making contact even with the key turned off. I don't know any simple or easy diagnosis.