Technically a 2000 Tahoe

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B Dub

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I thought this would fit better here rather than in the 2000+ thread, since it is the 5.7 square body style. I have a 2000 Z71 Tahoe. 150,000 ish miles. Bought it July of 2018. Clean carfax. Drove fine for about a year then the electrical zombies and gremlins surfaced. Keep in mind I have done nothing to it or made any modifications, other than replacing the fuel pump (ac delco) and some of the front end components. They were ok but just wanted to have a little new stuff in those spots. And replaced the wheels. Originals were awful. lol.

Here goes.......(keep in mind, I am a moron, so hope this all makes sense)

Starting in June of this year 2019
1. One of my employees noticed, leaving work one day, that when I hit the brakes my reverse lights also come on. Who needs reverse lights anyway so I just yanked them out.
2. Driver side window started not rolling down at will. Sometimes yes, sometimes no. I replaced the power module thing under the window and lock control panel. Works better, but still doesn't work sometimes.
3. Noticed one night, while trying to use my brake lights while backing up at the house that while in reverse the tail lights work but not the brake lights. Except the 3rd one up top.
4. Then once again an employee noticed that I have the 3rd top brake light, but not the other 2. Even while in drive or in park. Nothing. Tried to see if they would work as the hazards. Hazard button didn't work. I noticed while pressing it up and down, that they would come on if I pressed the button down and to the left. So I shoved a small *** of tape in there to hold it over temporarily.
5. About a week later, I drove my son to football practice and shut of the tahoe for about 5 mins then tried to fire up and go home. It would turn over and start to fire up then die. Over and Over. Called a tow truck. towed it back to my business, rolled it off and hopped in and it fired right up fine. Worked for several weeks fine. Employee noticed the crankshaft position sensor was loose and the wires to it were bare and exposed. He cleaned it up, taped it and all good for now.
6. couple weeks later while again driving to football practice one morning, I hit the blinker to turn right and the blower motor for the ac shut off. I jiggled the ac controls and was able to get it to come back on.
7. I replaced the entire blinker switch, which controls the hazards also. Perfect......for about a week.
8. Then, just yesterday I drove to work fine. About 30 mins later I had to run home.....When I hit the key everything lit up then went dark, dead. Nothing. I turned the key back off and in the off position the flasher relay behind the brake pedal started buzzing loud. Turn the key on and it stops. No lights or accessories. No Start . Ordered a relay (acdelco) and put it in and hit the key. Same thing first try. Second try I got lights and accessories back and no relay buzzing. Employee told me the computer may be resetting so leave it in on position for about 60 seconds. I did and it started right up fine. That was yesterday.
9. Today........while running some errands I felt a weird blip in the tahoe. On interstate doing about 65mph. Dash lights flickered and I felt the truck loose power for about half a second. Maybe not even that long. It caught my attention big time so I moved over to the right lane. Then BAM!!! The tahoe goes 100% totally dark, dead. Electrically and mechanically. I was able to bump the shifter to neutral and exit. Once stopped I hit the key and it started then immediately died just like a month or so ago at football practice. 2nd time I tried, it started up and I drove it to my fathers house nearby and parked it.

I am scared to death to drive this thing. Next time I air up a tire, the tranny may go out. Or if I replace a headlight, the dashlights may turn rainbow color or something. ugh. And I dang sure aint taking it to the deer woods next month. hour from town and sketchy cell servcie....no way.

I have wife, kids, father, and employees making fun of me for driving an old Chevy. But I just can't leave the square body models just yet. Lol

HELP Please. Any ideas. Other than the local demo derby?

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Doubeleive

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START WITH THE K.I.S.S. method, start with checking the battery and battery cables and grounds get a wire brush and take the cables off clean them even if they look ok, also clean where they bolt to the body and engine, clean or replace the rear light sockets over time they get corrosion or just burnt any build up will prevent them from working properly, a small screw driver and some sand paper can be used to clean up all the little metal contacts.
 

R3cord303

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Is it possible you got a flood vehicle? As in the vehicle was involved in one of the big hurricanes from the past couple years? And they got it working enough to sell, and didn't report the flood to insurance?
 

96-2D-Hoe

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I had the Tahoe die while i left it running to go in a store, and when I came back it didn't want to start, spluttering, and I think my dash lights went out completely, but that only happened once. Also had the weird relay buzzing quite a few times. But, 'knocks on wood', since I thoroughly cleaned up my battery terminals and got new bolts, thoroughly cleaned up all the main grounds, and any little ones I see too, neither issue has happened again. I thought I needed a new fuel pump as it was whining but after cleaning the grounds (and one at the pump) it quietened right down and I haven't changed it. FYI and mines a Southern California truck that has seen little weather.
Best of luck with yours.

PS. Also cleaned cables to alternator and the main positive that runs across the rad to the fuse block on the drivers side close to the firewall. (I was surprised to see some corrosion on my fuse block.) I also pulled and replaced every fuse and relay to get a better contact.
 
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B Dub

B Dub

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Battery is an Interstate and I replaced it when I got the vehicle last year. I will check the terminals again. They seem tight but I have seen bad terminals cause weird probs as well. As far as a flood vehicle, I thought of that as well. Not sure why it was fine no problems for 1 year then it went bonkers, but that is a thought. I am in North Texas and It was sold new in Arizona and spent most of its life there and in southern Idaho before I got it.
 
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B Dub

B Dub

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What about something like the key switch. That is something that if there is a short or something jacked up could cause the entire truck to die instantly both engine and electrical. When it die on interstate it was literally as if I turned the key off. Just grasping at ideas. Thanks, for the input. I do have an Arkansas Alumni sticker on the back window. If I removed that do yall think it might help. lol
 

Doubeleive

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What about something like the key switch. That is something that if there is a short or something jacked up could cause the entire truck to die instantly both engine and electrical. When it die on interstate it was literally as if I turned the key off. Just grasping at ideas. Thanks, for the input. I do have an Arkansas Alumni sticker on the back window. If I removed that do yall think it might help. lol
The random shut down on the road could be the ignition control module (icm) if your's has one that is a common reason for the sudden death for no reason and then starting and running fine again until the next time.
 

96-2D-Hoe

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What about something like the key switch.
The ignition key barrel itself has no electrical contacts. The ignition switch is below and is mechanically operated from the ignition barrel above. I went through all of this myself, wondering what I needed to replace. But that was about a year ago and I haven't replaced anything. Of course yours may be something else and need parts, but I had similar issue/s and they've not returned. Crosses fingers.
 

east302

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Are there any codes stored...especially with the iffy connection at the CKP sensor? Does the ‘service engine soon’ light work—comes on at startup?

The reverse lights are powered by the transmission range switch. The brake lights are powered through the turn signal switch and meet the reverse light power source at connector C409. I wonder if you have an issue at that connector and if it’s somehow messing with the function of the transmission neutral position switch, causing your other issues.

I kind of doubt that it is (the loss of all power seems to point to a bad connection at the battery) but it may be worth a shot to disconnect C409, clean it up and see what happens. I found two diagrams showing the location of 409. Not sure which is correct so I copied both. It’s pretty much just going to have the connector and then a split to each taillight.

While it’s apart, put it in reverse (don’t apply the brakes, maybe just jack up the back) and see if you have voltage at cavity C. You should have voltage there. Compare in park where there should be no voltage.

Also confirm that you have voltage at cavities B and D with brakes applied in Park.

The transmission switch and your back lights are grounded at G401. Might as well make sure it looks presentable while you’re back there.

The power window is probably a failing motor. Sometimes you can get them to cooperate by tapping on the door panel - roughly to the upper left of the lower speaker.

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