[Russel Heinonen]

I have an 04 z71 colorado, and the battery light comes on randomly and shuts off, on the driver side rear i have no running light, i have both rear brake lights, and both back up lights, but i hit the left blinker and the left rear blinker blinks fast then slow then shuts off, and when i hit the right rear blinker, nothing, anyone have similar problems or know a solution? Alternator mabye? It doesnt stall or dim the lights so idk, also the climate controll lights went out too

 

[10Canyon53]

I would start with your ground splice packs. They are a known issue on these trucks. I had electrical gremlins several years ago and after some research on here I pulled off the one on the passenger side, cleaned up the bracket, sanded the spot where it bolts to the fender until it was bare metal, bolted it back together and sprayed with battery terminal protectant. That was close to 100,000 miles ago and have had zero electrical issues since. You can find a ton of useful info on the subject here: the "ground problem" and 355 "Splice Packs"

 

[Dragon08]

checking the grounds is always a wise move. Also, you need to check on your battery and charging system. Take it up to your favorite parts store and ask them to check the battery and alternator. Our trucks do not have a voltage gauge on the dash. I use a device i plug into the aux power port to see what the system voltage is. I also have that value on my BT OBDII app.
Start simple. Pull the bulbs out and check for corrosion or bad contacts. Of course, make sure the bulbs are good too.

In this nasty cold, my truck pushes 15 volts for a while after start up. Once the battery warms up a little, it will drop to 13.4. On super cold days like now, I worry about it blowing bulbs with the high voltage.

 

[OldGuy]

All that info is great. That passenger side ground is the source of lots of problems with lighting, blower motor and other issues. Once I got that figured out, I still had some tail light issues and found that the contacts inside the bulb sockets were all burnt and crusty looking. I replaced several of the sockets with ones I found at a u-pull lot, but I had to purchase some and no parts stores had them in stock. Our trucks have terrible electrical design. The wires for the lights are very small and the ground wire is crazy! All other tail light sockets have 3 wires. One for brake/blinker, one for tail light and one for ground. Our sockets have 5! Ground in, ground out, tail light in, tail light out and blinker/brake. The ground wire goes in to the socket and then out of the socket and into the socket below it. So, you have one small ground wire that goes to all the sockets (3) on your tail light! In the "help" section of most auto parts stores, they'll have replacement sockets that will be marked with the bulb that it is for. I've gradually replaced all of mine. The replacements will not have the same number of wires and all the the wires will be black! That makes it fun!