Crazy power loss issues? Could use some advice.

Mmmayhall1 · February 2, 2017

Been having some issues for the last few months but have not been able to narrow it down and I'm afraid a mechanic would just swap expensive parts to fix it.

It started one day driving down the road. All gauge needles bounced around, headlights flickered, and the door locks repeatedly locked and unlocked rapidly. This went on for about 30 seconds. This happened a few times. It would be fine for a few days, then happen again.

It started getting worse. All of the above, but it would also drop out of gear and just rev. I would have to pull over, turn it off, and crank it back up to be able to drive again.

It started getting worse. All of the above, but when I would pull over and turn it off, nothing. No power to anything, even door locks or lights. Totally dead. I should note here that I checked all connections under the hood. Because these issues appear while driving and when completely off, it's hard for me to point at the alternator or battery.

Here is the strange thing. The first time it died completely, I decided to start checking for loose cables on the BCM. I needed to back the driver seat up, so I instinctively used the power switch to move it (which shouldn't have worked since not even the door locks worked). Well, the seat did move and as soon as it did, power was restored. I saw the gauges flicker and lights came back on. Sure enough, it cranked right up. The last 5 or 6 times I have traveled to a location and turned the vehicle off, all power would be gone (couldn't even lock the doors with power locks). I bump the driver seat once and everything is back to normal. Also, when it drops out of gear while driving, I shift the driver seat and it's fine again.

So maybe a short on the driver seat? Well, when everything is normal while stopped or driving, sliding the driver seat doesn't affect anything. I see no flicker or any of the above symptoms. It seems to only fix the problem once it arises. Almost like it kickstarts something.

One last thing is that sometimes I use my left blinker and can definitely notice that flicker and gauge issues directly relate to that. Additionally, sometimes I see flicker immediately after letting off of the accelerator. I don't know how all of that is related, but it was definitely repeatable. Any help would be appreciated with this crazy issue. Change the BCM maybe?

goborgoh · February 3, 2017

Have your removed the terminals off the battery and cleaned them? Also check and clean ALL of your grounds. Do you know how to check them with a multimeter?

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Mmmayhall1 · February 3, 2017

I have checked and cleaned the post connections. I checked all grounds that I could find. Tonight I will try to find a layout and check them all. I have a multimeter. What do I need to check? Just a good short at each connection or do I need to check for a specific resistance?

Something else odd just happened. Park and turned off truck. No power. Needed to lock doors so I bumped the driver seat once and all power restored. Locked doors. Went to leave about an hour later and no power again until I bumped the seat again. What could possibly have changed during this time?

Coby7 · February 3, 2017

Knowing what year truck would help here....

Mmmayhall1 · February 3, 2017

I meant to add that to the bottom of my post and forgot.

2011 Chevy Silverado 1500LT

davester · February 3, 2017

There are a whole bunch of ground locations all over the truck, engine compartment, in the cab, on the frame.

Mmmayhall1 · February 3, 2017

Started cleaning grounds and the frame ground was pretty nasty. After hooking the negative terminal back up, I had lights and everything. We will see if it messes up again driving tomorrow. Thanks for the responses.

goborgoh · February 7, 2017

Started cleaning grounds and the frame ground was pretty nasty. After hooking the negative terminal back up, I had lights and everything. We will see if it messes up again driving tomorrow. Thanks for the responses.

Did this fix it?

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Mmmayhall1 · February 7, 2017

Yes. It was an immediate difference when I started it back up and had been perfect since. I know it fixed it because some of the problems that I could force to happen, I can't do anymore.