Nbs Electrical Issue At 40k Miles

[EXSlider400]

This really gets me hot. I have a 2007 Sierra NBS and the dealer won't help because i am 3 thousand miles over the warranty (39K on odometer).

 

When running, the lights started to blink once every few minutes, just a quick on/of. The blink also dropes my battery to 10 volts, my guage needles all go left (off), the radio resets, and then all returns to normal. It's like someone is turning off my truck and then back onn really quick. Caused my ABS light to cut on, but no engine codes. Even when not running, the dome light sometimes is very very dim when i open the door, then when i turn the key to accessory they get bright.

 

Also when shifting, is hesitates a second then shifts hard.

 

I think it may the the ignition switch(key switch) . My battery is a few months old and connections are tight (also have battery protector on connections). I don't think it's the altanator because my guages & Radio wouldn't turn off/reset (clock goes to 12:00). Someone at work said they had to replace their clock spring, but that is only connected to the air bag and horn...

[mfennema]

Back in the day (3 years ago) when I owned a '97 Blazer, I had this same issue. In my case, Chevy decided it was a great idea to run the wiring harness for the seat controls above the seat rail, below the cushion. And so an electrical short was born. Whenever I would move my leg just right, the lights would blink on and off. Never could figure out what it was, but one day I was jammin to a song on my stock stereo and started movin my leg to the beat and the lights started blinking along. All in all, I would say to look for a short somewhere and see if there are certain times that it does it, meaning are there any conditions that it always does it? JM2C

[Draenor]

Could be the ign cylinder. I know you said you checked the battery connections, but have you checked the engine ground?

 

 

Like Mitch said, ake a peek around and see if you can find any wires that are shorting out. I wouldn't think too much on this since you didnt say your were blowing fuses. Better safe than sorry.....

[EXSlider400]

no, didn't check the engine ground, but will. No i have to fix it, its cutting out and shifting funny and eventually is going to damage something major... or catch fire... Still surprised no codes are tripping.

[mfennema]

I never blew any fuses either though so its a viable issue if you can't find anything wrong with the ignition.

[bill190]

Actually there are two things which could cause these symptoms. A loose main connection/ground. Or an intermittent short in the main electrical wires prior to any fuses.

 

If you were to quickly disconnect, then reconnect a main wire, this would happen. And also if you were to very briefly short the main + and - connections, this would happen.

 

Basically turn on the ignition without starting the vehicle. Turn on things you can hear or perhaps lights on at night. Then go around and "wiggle" all the big wires under the hood. Main wires to battery, alternator, to fuse block, etc.

 

Also examine the main + positive wires for anywhere they might be rubbing against a sharp piece of metal. If you can't see the back side of the wire, feel the back side with your hand or use a mirror and flash light. Look for any signs of arcing.

 

And a sharp piece of metal can make a small slit like a knife would into a wire harness. And this would be on the back side where you could not see. So look for a small slit in any main wire harness next to sharp pieces of metal.

 

If this was "past" where the fuses are, a fuse should have blown if it is a short. So that makes things easier!