As the title states, I have a 2005 Chevy Impala with the 3.4L (3400) engine. I can turn the key and I can hear and feel the starter solenoid working, but the starter motor doesn't turn.
I can use a jump pack connected to the battery to get it started, and it starts easily, but trying to get a jump from another (running) car doesn't work. I tested the jumper cables with the connectivity test of my multimeter and it shows the cables to be good.
Also, the dash lights and radio turn on and off multiple times when I have the key turned trying to start the car. Occasionally, the dash cluster will "bounce" around after turning off the key, as if it is getting power then disconnecting, then getting power and disconnecting, and it does that a couple times a second for 2-3 seconds. But it doesn't always do that.
To go further, I got another starter from a junk yard and had it tested at O'Rilley Auto Parts, which showed it was a good starter. After I installed it, the car is still having the same non-starting issue.
I have a cheap wireless ODBII tester and it shows that the alternator is putting out +14V to charge the battery, the battery charges to +14V, the car runs fairly smoothly when it's running, and there are apparently no fault codes, even though the ABS and Traction control lights on the dash are lit.
Putting a multimeter to the battery when the car is off shows that it does actually charge to +14V, and when I try starting it without any jump pack or 2nd car, it drops to 9.5V or so. The battery is less than a year old and is Champion brand.
I can have the car running in the driveway idling without any issue and it warmed up and the battery fully charged, turn off the key, then try to start it and it still not restart.
I've doublechecked that the battery posts are securely attached and that the wires to the started are nice and tight. I previously cleaned the side posts and bolts when I did some work 1-2 months ago. I also applied battery terminal grease. This car had been working just fine since then without any issues.
I've checked fuses and the only one that's blown is for the cigarette lighter.
I've swapped relays with existing relays of the same model within the fuse box for the ignition and starter relays independently. I did the same for the "battery run down protection" relay. Swapping out the relays made no difference. There didn't seem to be any significant corrosion. I live in Southern Nevada, so there's not that much humidity, anyway.
I've had ignition problems with this before, but that was due to the previous owner replacing the keyed ignition switch in the dash and looping (not even twisting) the wires together, then covering them with duct tape. It caused the security system to not recognize the key about half the time. I removed the dried up duct tape, soldered the wires together, and used heat shrink to cover the connections, and haven't had any problems starting this car until now. And to be clear, it tries to start the car, it just doesn't start. When I was having the loose ignition wire issue, it didn't even try to start at all.
Tapping on the starter doesn't work and I can hear and feel the solenoid working (like I mentioned before). There wasn't significant dirt or corrosion on the starter terminals, either.
I've watched videos and read various articles here and elsewhere online and none of them have fixed my issue so far, so what am I missing? Why won't this car start on it's own and why will it start on a jump pack, but not jumper cables?
Edit:
I've tried some new things with no real difference yet.
I removed every fuse in the two cabin fuse boxes, one at a time, to see if there was something in the dash or otherwise in the cabin shorting things out. Nothing changed, except when I removed fuses that were required for the PCM/BCM or cluster to function, and then nothing at all happened when I turned the key.
I also removed the relays, one at a time, and didn't have any improvements when I turned the key.
I also doublechecked the main power wire connectors to the starter for corrosion, and sanded off what there was with 120 grit sandpaper, but that didn't make any difference.
So that rules out a lot of things.
What I did notice is that if I held the key for more than 2 seconds trying to start the car, it would "pulse" power to the dash/cluster 4 times, and that includes 2 pulses after I let go of the key.
I also noticed that if I turn the key to "Start" slowly, there are multiple dead spots where there's no power at all, even to the dash. I'd expect one as a separation between "Run" and "Start", but not the +3 I noticed. And they were the same dead spots when I let the key return to "Run".
I'm now thinking it might be a bad key ignition. Especially since it was previously replaced by someone who didn't know how to do basic wiring. To test this theory, I'm going to see if I can bypass the ignition key and see if that starts the car.
I'm still going to get the battery tested, as MTA suggests below. And I'm not ruling out bad wiring, as Pᴀᴜʟsᴛᴇʀ2 suggests below, but I'm done for tonight.
Edit 2:
I forgot to mention that this car was in a minor fender bender 2-3 months ago, in the quarter panel where the battery is. I don't know why I forgot to mention it, but it was probably because it was minor and several months ago, so I didn't think it would matter. A comment below now makes me think the battery may have been damaged at that time. I'm not the main driver of this car, as a friend owns it, so they may have had this issue longer than I'm led to believe. Then again, I've worked on this car since the accident without any issues starting. But it may have simply had more time for whatever broke in the battery to finally show itself or finish breaking during the regular movements of driving.
IDK, it's a theory, anyway. It's currently as valid as anything else so far, as I haven't yet had a chance to check it out this morning, but I'm headed out there now.
Edit 3:
I just got back from Autozone and the battery was apparently so dead that they couldn't test it, which, to them, shows that it's a bad battery. Especially after telling them some of what I've written in above.
So, I'm going to take the car back to where the battery was purchased and have them test it and warranty replace it when it shows how bad it is.
If that doesn't work, I'll be back here updating this question.
Resolution:
It was a bad battery and battery post. The battery was still under warranty and the mechanic that installed the battery originally replaced the post for free, since the battery was less than a year old and they admit they should have replaced when they did the battery.
