Justin, on one post you say your headlights flash. On another , you say the headlights blink. Please explain the flash or the blink. Are you saying the headlights dim/slightly blink or are they momentarily brightening /flash? When do they do that ? Is it when you are coming to a stop ? Is it when you are driving at a steady speed? This info would be very helpful.

 

My '02 4x4 started doing this same thing about 2 years ago and I can't figure out why. I used to have LED exterior lights that I installed sometime in 2018 and didn't have any electrical issues then. I also installed the correct LED flasher relay to make the turn signals work correctly. In 2020 I had my battery fail and needed replacement, so I did replace it.

Then sometime in early 2023 I started to notice strange electrical issues. The voltage gauge would "wiggle" somewhere between 13 and 14 volts. But that wasn't the weird thing. My dashboard lights would also start flashing with the turn signal. When I unplugged the amber front lights to diagnose the issue, I found that the LED lights I installed a couple years back had started to fail. The electrical pins got so hot (I'm guessing) that they started to fall out. When only one pin was making contact, the dashboard would flash with the turn signal. I saw this as a sign to ditch the LED lights and go back to stock halogens.

After a while, my Blazer began to have trouble starting. Can't be the starter because I already replaced it a little while ago before the dashboard flashing started.
​​​I took my Blazer to a shop so the techs there can sort out what these electrical gremlins are. They had no idea what would cause the dashboard to flash with the turn signals nor how to reproduce it. So I just left it at that. They tested battery and found it needs replacement. So that one lasted about 3 years. I asked them to look into the voltage gauge wiggling and they couldn't find an answer for that either. The shop parts-cannoned the issue with another PCM, but the issue persisted. So they eventually came to the conclusion that the gauge itself in the cluster was faulty. I believed them because I have a similar issue with my fuel gauge after so many different pump replacements.

So with new a battery equipped and nothing wrong with the alternator, they tested that too, I just forgot about the issue for the next 18 months. Very recently I had yet another battery failure that left me stranded on the side of the road while visiting family way out in the country side. I wasn't paying attention to the voltage during the trip out to the country side, but the trip back home started out with a very weak battery, and it just quickly drained completely flat as I drove. While driving the voltage gauge dropped to about 9v, all my interior lights and dashboard went out, and the engine only kept running so as long as the distributor kept working, but the whole ignition system eventually stopped working. Why wasn't the alternator charging the battery? I thought for sure bad alternator. But after an over night trickle charge, everything was fine. I had AutoZone test everything and they found the battery was bad. Would crank fine but didn't have any more reserve capacity to hold a charge. So that battery lasted about 18 months.

What do you guys think is going on here? Could this voltage gauge "wiggle" be contributing to premature battery failure? I really don't want another instance where my Blazer leaves me stranded again in the dark. It's my daily driver and I put about 15k miles per year on it.