Had battery tested at Auto zone. Went in 30 minutes before they closed so the guy wasn't thrilled at all about helping me out.

I asked him if he could load test it and he said his tool just says if it's good or not. By this point I can tell the guy either thinks I'm stupid or he just doesn't know how to do his job or use the device.

He came out and put his tool on the battery. I watched the whole time. The battery read 97% charged and something about capacity but that also was in the green. As we're standing there, the a/c condenser fan kick in and you can visually see the huge voltage drop in the interior lights and headlights. He says "wow, that's a big drop", unhooks his tool and starts walking back in.

So, I'm assuming he did not load test. I'll buy a cheap one on amazon and do it myself. Good to have one around anyways.

One thing I've come to notice though. This big voltage drop only occurs when the car is running. If the car is off I can press the brake pedal and the interior light barely dims. Start the car up and press brake pedal and interior light noticeably dims as does the speed of the fuel pump too. It is very brief, like a second or two, then back to regular brightness. I have also raised the rpm's of the engine and apply the brakes and though it still happens, it's slightly not as bad. I do want to state that I know some cars it's normal for a little dim, especially something high current, but this seems excessive to me.

I've checked, cleaned, inspected all grounding points under the hood and to the transmission. Battery terminals are tight and so are the bolts holding fuse box down. I've even unhooked the dash cam and unplugged all charges, etc.

I mean, I can live with it honestly. But if its creating a low voltage situation every time I apply brake could that have any bearing on this being my 3rd fuel pump?

I'm going to check what bulb I have in the tail lights. I know i've changed them out in the past year or two. Would running the 3157 back there as opposed to the 3057 create any issues? They both fit and it's completely possible I put the wrong one in. Will check on that.

 

It is the cause of the fuel pump problem.
You checked the cables between the alternator and the starter and the fuse box? If those are good, my next guess would be the alternator or maybe the current sensor. There might be a fusible link between the starter and aslternator, **** it for continuity.

 

Replace with correct bulbs 3057 in the rear

 

Had the right bulbs in so it wasn't that.

Tried the parasitic draw test that Donbrew posted link to but I think my multimeter is broken or something because it's reading zero no matter what range i choose in the amp setting. yes, the red lead is plugged into the "amps" jack and the black into the "com" jack.

Also bought a motopower battery tester to check the battery. It's saying the battery is good. I question this though. It's a 740CA battery and the tester said it was putting out 540CA and passed. Is this right. Said battery was 71% charged and I had just driven it home for 25 mins. I also load tested the battery with an old school analog tester and that also passed.

I'm waiting on a new meter and then I will try the draw test again. Will also check the diode on alternator as well.

 

71% is dead. It is volts that count. The battery is either dead or the alternator is not working right.

 

Defective battery, loose alternator wire connection.

 

Maybe bad Serpentine belt/tensioner.

 

Put new battery tester on first thing this morning. Did not run car. Reading 12.27 volts, 437 CA. Start up test said low voltage and battery condition POOR. Charging test verified alternator was charging OK> The tester does not like this battery today. But yes, everything is pointing towards the battery.

I tested diode on alternator and it was good. Red lead to case and black lead to stud on alternator on diode setting on new meter. Got a reading of .438. Reversed the leads and it reads zero so thats good.

Lastly, performed the parasitic draw test exactly the way it was described in the video Donbrew posted earlier. I have a reading of 1.7 MA, or .17 A but this is well within spec, correct? Video states 50 MA or less. I did pull fuses just to see and the only fuses that made it drop down were the radio fuse which made it drop to around .11 A and the interior light fuse also made it drop to around .08 A. Car was asleep and all the interior light pins I had clamped so they weren't on.

Before I replace the battery I need to confirm that the draw I;m seeing is normal. Not sure why the radio pulls that little bit but it is aftermarket which needed an aftermarket interface kit soldered into the radio wiring harness in order for the chime to work. I will pull dash apart this weekend to investigate and make sure no wires are shorting, etc.

 

I asked in #2 about after market mods, the answer was none; now you have added 2 at least.
This is the first mention of after market radio. After market radios need a switched and a constant power source. Where does it get them from? The original radio only had the constant and the BCM provided a ON signal. I bet the adapter was installed incorrectly.

 

X2 aftermarket adapter should be plug and play not cut and split crimp connectors, which tend to come loose with vibrations.