I'm just surprised you can hear the fuel pump while the engine is running. Guess I never listened for it before.

 

Do you ever notice older cars on the road with one dim headlight ? That is usually because of a ground issue at that headlight.
What you’re describing with the voltage loss and such could just be a ground problem.

 

this was a post from Donbrew quite a number of years ago. TSB #PIC4108G- battery draw from BCM2 fuse

https://www.chevyhhr.net/forums/prob...a-52318/page2/

this is exactly the draw amount i'm seeing and when i remove this fuse it goes away. what would cause a STG on one of the mentioned circuits? I don't have any problems with power door locks or dome lights except for the dome lights flickering when i apply the brakes along with the headlights and fuel pump. Guess i'm tracing some wires. Anyone have a diagram of the BCM plugs and pins?

 

Did you read FMG’s and my post regarding ground connections and alternator issues? As I mentioned it’s not that complicated!

 

Your Shop Manual has all of the wiring diagrams and pinouts.

BCM2 fuse is in position #6 under hood fuse box.
Since your dome light flickers, I would be looking there. Maybe the dimmer wheel.
Which dome light flickers? The front one goes to ground through the dimmer wheel to left end of the dash. The rear and reading lights go to ground under the left tail light.

Just to be absolutely sure; no LED lights in anywhere? Especially the dome lights.

 

Oldblue, yes I read your post about alternator and ground issues. I have checked, disconnected and cleaned, tightened every ground I can see and physically access. I have done the same with the positive side of the charging system as well. Every single point of connection on the positive line I have removed and cleaned to bare metal and reconnected. Brand new starter. I have checked the fused line from alternator for continuity and its good. The belt is brand new and not slipping. I have turned every single thing on in the car to load alternator and I get a charging voltage of 14.4 volts. With everything on still I have checked for voltage drop and get .02v on the ground side and .44v on the positive side. Diode checks good for current out and not backwards. Brand new battery and clean terminals. Alternator seems to be doing what it's supposed to be doing however every morning I check battery voltage it is low at 12.4 almost every day and I drive it everyday to work.

Donbrew- Its all the dome lights along with the headlights and the fuel pump and NO led lights anywhere on car. It is very quick then back to normal until I apply brakes again or condenser fan comes on. I'm with you though as far as looking into the dome lights being the problem. Was even thinking about brake light switch. I've already confirmed the correct bulbs in brake light. It's worse when I first start the car obviously since the battery isn't fully charged. After the car runs a few minutes It's not quite as obvious but still there. I'm sure this is because the battery catches up on charge. Like I stated in a post way back in the beginning, I can learn to live with this condition but every time I see the lights dim I feel like it's because of a low voltage issue and its playing havoc on my fuel pump and I'll be ordering my 4th pump again in a few months.

So, I feel we need to address the draw on the battery which I've narrowed down to that BCM 2 fuse. Still trying to understand what would cause a STG in the mentioned wires of that TSB. I will be putting the factory radio back in tomorrow to see if that makes the BCM happy and the draw disappear. I doubt it will change anything but have to try anyways to satisfy myself. Last option, take it to the dealer which I'm trying my hardest not to do but I'm about at the end of my rope!

The service manual, do you mean the one you have free links to?

 

In 09, they went from 2 switches on the brake pedal, to a pedal position sensor. For the brake lights and the cruise control. It's the same part number as on the accelerator pedal. Don has said it's a potentiometer. You might try turning the cruise control off. You might try swapping it with the accelerator pedal position sensor. I swapped mine years ago for a very different issue, and have not had any related problem yet.

CORRECTION for future readers : the accelerator pedal position sensor is different. It is the brake pedal and clutch pedal position sensors that are the same.

 

how do you turn off cruise control, just pull the fuse? And from what I'm understanding you're saying brake pedal and accelerator pedal sensors are the same? How would/can you test the dimmer potentiometer?

 

YES.

The BCM2 and BCM3 fuses supplies the otherwise unfused circuits in the BCM box. The maxi fuse near the battery powers the BCM computer.

There is a difference between "flicker" and "dim". Come to think, why are the dome lights on while you are driving? The dome lights have a way of melting in the innards, take the covers off and inspect them.

The dealer techs know as much as you, they just get paid. The Service Manual that I link to is the exact one they have access to, but don't bother to read.

 

Donbrew, not driving with dome lights on. This is while i'm sitting idle and drivers door open and car running. The headlights I can see at night while driving and applying brake. I could care less that the dome light is doing it because dome light only comes on when you open door. But it's doing it along with the headlights (and that's why I mentioned it). Its a string of events all connected.

You are also correct. There's a huge difference between flicker and dim. I am learning to better explain things.

As far as the dealer goes, I had a small hope that there would be just this one "skilled" tech that was good at diagnostics. You know, the old timer that's been there 25+ years and goes way back to the old school days. But I guess those guys are gone.

This is way off topic BUT, went to Firestone a few weeks ago for an alignment. I specifically asked them to set each wheel at .1 positive toe. they do the alignment and i look at the specs and they set each wheel at .01. I asked the store manager why he didn't set it at the .1 like I asked also reminding him that it was GM specs. He tells me I'd be way out of spec if he did that. He got all hissy with me and angry and made a scene and comes at me with "i'm a certified ASE technician. I know what i'm talking about" I told him, no you don't because .01 is almost zero toe and although technically in spec it's not what is called for. I even showed him right there on the spec sheet it says .20-.40 total toe is what's called for. he tells me they can't do anything else for me and walks away. Told them I wasn't paying until they reschedule me to fix it. Took it back a week later and they set it the way its supposed to be.

So, I agree with some of these guys not knowing anymore than us DIYers. There are guys that really know what they're doing and then there aren't!