Battery problems after knock sensor replacement

[Blackmar401]

2003 tahoe 4.8, So I'm not a big car guy and this is probably the biggest repair I have taken on. Got the knock sensors in and actually snapped a stud putting it back together. Torque wrench only went to 10ftlbs. Anyways, I welded a bolt to it and backed it out and continued on. Snapped the pcv tube so I replaced the valve(seems to be missing something, new one is empty and old one has guts that move around)Reattached everything and started it up. Ran like it was before for a few minutes then seemed to get smoother. Idled for like 10 or 15 minutes then drove it for 5. The wife then noticed the battery light and the screen saying battery not charging. When the battery is connected to the car and I try to charge it the charger lights up "bad battery" when I disconnected it suddenly it would charge. I was getting like 8v at the battery and alternator. The middle brown wire (watched a video saying this should read like 14 when running) on the alternator also reads the same . I remember seeing the battery light I think right before starting the repair but I'm not 100%. so basically I'm wondering if I could have broken a wire(it was like 20 degrees and raining/snowing while I did the repairs. I broke a bunch of the gray clips on the injectors but they seemed to reconnect no problem. Is it more likely that it's just a coincidence and the alternator failed right before or during/after the repair. We really need this vehicle on the road but I don't want to just buy an unneeded alternator and or battery as I'm already like $700 into this with ac Delco sensors, new gasket and tools that I needed. Any suggestions would be greatly appreciated.

 

[wjburken]

2003 tahoe 4.8, So I'm not a big car guy and this is probably the biggest repair I have taken on. Got the knock sensors in and actually snapped a stud putting it back together. Torque wrench only went to 10ftlbs. Anyways, I welded a bolt to it and backed it out and continued on. Snapped the pcv tube so I replaced the valve(seems to be missing something, new one is empty and old one has guts that move around)Reattached everything and started it up. Ran like it was before for a few minutes then seemed to get smoother. Idled for like 10 or 15 minutes then drove it for 5. The wife then noticed the battery light and the screen saying battery not charging. When the battery is connected to the car and I try to charge it the charger lights up "bad battery" when I disconnected it suddenly it would charge. I was getting like 8v at the battery and alternator. The middle brown wire (watched a video saying this should read like 14 when running) on the alternator also reads the same . I remember seeing the battery light I think right before starting the repair but I'm not 100%. so basically I'm wondering if I could have broken a wire(it was like 20 degrees and raining/snowing while I did the repairs. I broke a bunch of the gray clips on the injectors but they seemed to reconnect no problem. Is it more likely that it's just a coincidence and the alternator failed right before or during/after the repair. We really need this vehicle on the road but I don't want to just buy an unneeded alternator and or battery as I'm already like $700 into this with ac Delco sensors, new gasket and tools that I needed. Any suggestions would be greatly appreciated.

Places like Auto Zone can test alternators for you. Might be worth finding a place and get it tested to confirm or deny a problematic alternator.

I would also check the ground connections under the hood, particularly in the area you were working, like from the firewall to the block.

 

[Fless]

Try not to post multiple threads on the same issue. Your responses will serve you better when they're in one thread.

 

[Blackmar401]

Try not to post multiple threads on the same issue. Your responses will serve you better when they're in one thread.

Just figured like most forums people tend to hang out in certain spots. Guy that never ventures out of the "engine," section won't see a post in "general " and the guy hanging in "general " won't see it posted in "engines". Is there a better way to reach both crowds?

 

[wjburken]

Just figured like most forums people tend to hang out in certain spots. Guy that never ventures out of the "engine," section won't see a post in "general " and the guy hanging in "general " won't see it posted in "engines". Is there a better way to reach both crowds?

Most of the active folks here simply browse all the new posts. I personally don’t pay much attention to which particular section a post is in when I first look. If it’s not clear what year vehicle it is about, I’ll look.

 

[Doubeleive]

where doesn't really matter as long as it in the correct section, but if you do not get any response to a post just bump it up with a reply and that moves it back up to the top of the list where it is more likely to be seen by someone. some post's slip by and end up 2-3 pages in with no response sometimes.
you could make a post and by the time it refreshes it could be 6-10 post's down the list already.

 

[rockola1971]

First make sure the battery is fully charged (battery charger) then start the Tahoe up and check battery voltage at the BATTERY (this voltage reading will be the alternator output voltage). You might want to also check the large gauge wire coming off the back of the alternator (red/pink) which goes to the positive terminal of the battery (this is the connection that allows the alternator to charge the battery). Inspect for damage to the wire, wire pinched by engine valley cover, etc.

 

[Blackmar401]

The battery was charging after I disconnected it from the harness. I also forgot there was a whining sound when acceleration for a week or two prior to this. Didn't realize how easy it was to pull the alternator, until i did last night but it was 2nd shift at all the auto places and apparently no one at night knows how to use the machine to test it, so I will be taking it with me to work and stopping on my way home. I feel like it either died at the perfect coincidental time, or maybe it even still works when driving faster. I didn't notice the light driving around but it came on when parked in the driveway.

 

[S33k3r]

You might get an airbag light when you get everything reinstalled. If you do, just drive it around for a couple of days and it should correct itself. We ran into this when we replaced the alternator on my daughter's Sierra. And I'll tell you this: the people in this forum came to my rescue when I had trouble getting the new alternator installed. I *still* appreciate that.

 

[Blackmar401]

Put a new alternator in and it solved the problem. I was very relieved as I thought I probably messed up some wiring and had a much bigger issue on my hands. I replaced the airbag sensors when I got the truck a couple years ago also.