Dead 04' Z71 Hoe. Went from no inter. lights to dead in 2 weeks time

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TacHoe

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Greetings fellow wrenchers, I wanted to catalog this for anyone who may run in to the same experiences in the future.


Leading up to 2004 Z71 Tahoe dying on me mid-drive (some background):

- A few months back in the dead of winter my truck wouldn't start - twice. By the time the second incident occurred I went and picked up a new battery (red top optima) and went on my merry way.


Fast forward 2 months


Interior lights stopped working one morning. I thought nothing of it and continued to live my life. However I was coming up on inspection time and knew I would have to care sooner than later as it had somehow effected my reverse lights as well... So I went out one morning and started to do some PMCS on her to see if anything in the engine bay, interior/exterior looked amiss. In my search I found #1 (below) and decided to enlist the assistance of my ole lady to help pull fuses from the interior fuse panel as my girthy hands didn't allow fitment in the tightly constrained spaces. I replaced the ground strap cable with a 4 ga. cable with ¼” ring terminals already on installed (autozone) and got the new fuse in and all was back to how it should be. Lights back on and able to pass my inspection with the reverse lights finally working.


1. Ground strap cable from the firewall to the hood was broken

o This in turn blew a fuse in the interior fuse panel (I will come back and edit this post to note which fuse blew and its location).


Recap: Results from the blown fuse/broken ground strap cable were:

o Interior/done lights all non-working

o reverse lights stopped working


Fast forward 1 month


The ole lady and I decided last Saturday night at 2230 hrs that we wanted some Jonny Rockets Malt Shakes (Mmm) and we jumped in the hoe and left out. When I cranked the truck I immediately received a “battery not charging” indicator on the DIC, accompanied by the customary red battery light popping on for about 4 seconds then off for about 10, and the battery volts dropping drastically on the display. Considering we are just down the street from our destination I figured we would be solid and we continued on our way. We get there, get our malt shakes and are happy as can be until I start the hoe back up; she’s sluggish to get going but starts. We are on our way and headed home finally. We get to the intersection of the main road and the shopping center and she hesitates to go, almost stalling. The light turns green and I start to accelerate through the light. At this point the hoe entirely dies on me. I lose everything from power steering to my brakes. Thankfully I wasn’t going too fast and just coasted diagonally through the intersection and up and over the curb on the other side, where I applied the e-brake (also thankfully recently adjusted and put new pads in) and came to a halt.


Ill spare the long boring wait for the AAA tow truck driver


Back home the next morning I went and pulled the Alternator and the brand spanking new red top, hopped in the ole lady’s trusty subie and went up to Adv. Auto where I bench tested both the Alt and the battery.


Battery was dead so they recharged it, hence the low volt reading on my display, and we bench tested the Alt 4 times to ensure the passing grade it was receiving was correct. In my time in the Army I learned not everything is always as it seems, so I scooped up a new 145 Alt (per my vin code) just in case and went back home to reinstall the OLD alt, that tested SAT. I cleaned up connection points at the alt ground and battery cable wires heavily with carb cleaner and a brass wire weapons cleaning brush and installed the old alt back in there. Connected the battery back up and cranked the hoe over – “Battery not charging” but she started (per the newly charged battery).


At this point you have to be screaming, “it’s your alternator you fugging pug”…. But how could it be when it tested SAT during bench testing? Simply put, the bench test cannot account for the load your vehicle puts on the alt.


Lesson:Things are not always as they seem, running through your check list of things smallest to largest (cheapest to expensive) can really show a lot. I learned from an SF commo guy, when working comms issues, to start small - checking connections (is it connected?) and power (is it plugged in?) and are the wires and cables intact (have they been compromised at a bend or are they brittle and breaking?). I have applied this same tactic to nearly everything in life that works and then for some reason doesn’t work.


CAVEAT: One caveat I have to this is that I run rear facing roof rack lights. From a friend of mine who is a master mechanic – he explained that: As I have these cut in to the reverse lights, this was the reason my interior lights affected my reverse lights when the initial problem occurred.


Now there may or may or may not be a correlation between the first events and the alt dying or maybe the first events were indicative of the follow on events. I am not sure. But I hope this information can help someone else out in the future. I will update this post when I get home with some details and the specific fuse that took out the interior light and a couple pics to show my hoe.


Thanks for reading and feel free to ask questions where I may have left ambiguity.
 

mattt

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So what ended up fixing your "Battery not charging" message? Have you figured it out as of yet? I just got the same message last night and this morning. It doesn't seem like an alternator would just give up the ghost as quickly as this one did, but I guess it's possible.
 
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TacHoe

TacHoe

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I would elicit the advice of my commo friend here:
  1. Check connections to the battery from the positive and ground wires.
  2. Also check the connections at your ground strap cable that connects from the firewall to the hood and the
    1. firewall down the back of the engine.
  3. Also check the cables that run to your alternator, the ground cable on that is a big one to check. Apparently it can come loose from vibrations over time.
  4. Fuses are next in line, however this was more of a redundancy move for me as when power surged on the system, that needed more power, it popped my fuse resulting in a loss of interior lights, and then finally all power as the alternator was intermittently failing.
I know there are other possibilities like the starter and whatnot but my philosophy (and I think this is generally most folks philosophy) is to start small and inexpensive and work your way up. Start with this and I will post pictures shortly of some of the points I mentioned.
 

mattt

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Did you end up replacing the alternator?
 
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TacHoe

TacHoe

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Did you end up replacing the alternator?

I did replace the OEM ALT (w/155K mi) and that was the fix immediately for me. But again it was initially intermittent so my symptoms led me down other paths initially (the broken ground strap cable, the blown fuse etc.).

BE SURE TO DISCONNECT THE BATTERY WHEN MESSING WITH THOSE GROUND WIRES/ BATTERY/ or the ALTERNATOR
 

mattt

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Ok, thank you. Mine was intermittent as well, for about 12 hours. On Monday night, when I first noticed the "battery not charging" message and saw it not charging on the gauge, it would eventually start to charge after running for about 1 minute. It is now at the point one day later where it's not charging at all. I guess I'll pull the alternator and have it checked as a first step. Thanks.
 
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TacHoe

TacHoe

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Ok, thank you. Mine was intermittent as well, for about 12 hours. On Monday night, when I first noticed the "battery not charging" message and saw it not charging on the gauge, it would eventually start to charge after running for about 1 minute. It is now at the point one day later where it's not charging at all. I guess I'll pull the alternator and have it checked as a first step. Thanks.

Just to note from my initial write up, bench testing my alternator (4 times) came back saying it was good to go every time. This is because it is not under load as it would be installed in your truck. SO it MAY test bad but it also may test good and give the false impression that you dont need a new ALT when in fact you may need a new one. Its a toss up, thankfully I had some guidance from a Master Mechanic whom pointed the load issue out.
 
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