Here to ask the experts for advice.

An electrical nightmare. Yet, hopefully not?

Hi everyone, I’m new here, also a new Tahoe owner. I’m a electromechanical tech for a blow molding facility, so I get troubleshooting and tasks. But the knowledge of those who am have been around these trucks a time or two is insanely valuable.

so here’s my story.
I bought my wife a 2000 Tahoe 4wd, about 2 days ago. About 150k miles. Bought from a close friend for a insane low price.
Mechanically this truck is outstanding. 4wd works very well, shifts great, very quiet and runs well. Was always maintained.
Except.

1) Dome override. If I click that button once it kills the DRL *headlights only, markers stay on* until I reset the battery.

I replaced the dome override/auto headlight switch, same issue occurs.
I’ve replaced the DLR relay with the rear defrost relay and the same error occurs.
As it stand you cannot press dome override or all hell will break loose.
No blown fuses.
All other lights work, tail lights, interior lights as if the truck knows it’s dark but will not turn the headlights back on.

2) Absolutely no interior lights work in the vehicle. Only Speedo/HVAC (behind the dash) lights are available. Maybe this has something to do with issue (1)?

3) Fuel gauge.
When the truck is in park and it starts up, reads empty, alerts me low fuel. As you start driving, the gauge will slowly go up at a alarming slow pace. It will take 15m of driving to show accurate fuel level.
*previous owner stated the fuel pump was replaced about a year ago, which includes the sending unit?*

could all these issues be involved with one another?
The last owner stated the truck did have a drain on it battery wise. I did not get a chance to hook my amp meter up with the trucks main battery circuit and start pulling fuses just yet, that’s soon.

I’m also looking for more details on the service air suspension alarm w/the resistors so I can take care of that also.

I was just wondering if any of these issues are common for other Tahoe owners. I’m pretty used to junk but I want this truck as operable for the wife as it can be therefore I can live a happier life.

thank you for all and any help/info. I will answer any follow ups as quickly as I can.

Welcome from NH.

Lots of great folks here who will give you their suggestions and perspectives.

One common theme for these trucks is when strange electrical-related issues start to appear, check all electrical ground connections, not just the battery ground, to ensure that they are clean and tight. I would recommend that you start there, as other folks read your issue description and start to chime in with their suggestions.

[QUOTE="Nick91l, post: 1409957, member: 3) Fuel gauge.
When the truck is in park and it starts up, reads empty, alerts me low fuel. As you start driving, the gauge will slowly go up at a alarming slow pace. It will take 15m of driving to show accurate fuel level.
*previous owner stated the fuel pump was replaced about a year ago, which includes the sending unit?*
.[/QUOTE]


Regarding the fuel gauge, if the previous owner used an aftermarket fuel pump that is your problem, it needs to be replaced, only use oem or ac delco parts. I had a similar issue, after replacing the fuel pump 3 times I learned my lesson, the 3rd time I bit the bullet and bought an ac delco fuel pump, have not have any issues in 3yrs. Congrats on your purchase, these SUVs are bullet proof with proper maintenance.

I'd say to check it with a Tech 2 (or another advanced scanner) to see what kinds of codes are showing up. There ought to be one for the service air suspension issue, and maybe others that would point to the issue.

Joseph Garcia said:

Welcome from NH.

Lots of great folks here who will give you their suggestions and perspectives.

One common theme for these trucks is when strange electrical-related issues start to appear, check all electrical ground connections, not just the battery ground, to ensure that they are clean and tight. I would recommend that you start there, as other folks read your issue description and start to chime in with their suggestions.

Click to expand...

Thanks a lot, that was definitely gonna be one of my tasks but now that you say that I’ll move it too the top of my priority list. About 15 degrees out here in PA, so I’m gonna try to make it till it gets a bit warmer haha.


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ivin74 said:

[QUOTE="Nick91l, post: 1409957, member: 3) Fuel gauge.
When the truck is in park and it starts up, reads empty, alerts me low fuel. As you start driving, the gauge will slowly go up at a alarming slow pace. It will take 15m of driving to show accurate fuel level.
*previous owner stated the fuel pump was replaced about a year ago, which includes the sending unit?*
.

Click to expand...

Regarding the fuel gauge, if the previous owner used an aftermarket fuel pump that is your problem, it needs to be replaced, only use oem or ac delco parts. I had a similar issue, after replacing the fuel pump 3 times I learned my lesson, the 3rd time I bit the bullet and bought an ac delco fuel pump, have not have any issues in 3yrs. Congrats on your purchase, these SUVs are bullet proof with proper maintenance.[/QUOTE]


That sounds about right for sure. I’ll definitely have to swap that out come spring. You said you had similar issues? Other than that, thanks. I was always a ford guy since I was a kid. I always loved her blazer, and this Tahoe is 20 years old but it’s got features of what seems to be a 2020. It’s a really neat truck for sure. I’m really digging it.


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Fless said:

I'd say to check it with a Tech 2 (or another advanced scanner) to see what kinds of codes are showing up. There ought to be one for the service air suspension issue, and maybe others that would point to the issue.

Click to expand...

I’ve been looking at good scan tools lately. I used to get by with a hobo fright scan tool for the longest time, but I’ve been looking at tech2 software for the laptop being is I have a fleet of GM vehicles now. Do you have any experience running tech2 on a computer? Or have a equivalent scan tool that works well for these GM trucks?


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Nick91l said:

I’ve been looking at good scan tools lately. I used to get by with a hobo fright scan tool for the longest time, but I’ve been looking at tech2 software for the laptop being is I have a fleet of GM vehicles now. Do you have any experience running tech2 on a computer? Or have a equivalent scan tool that works well for these GM trucks?


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Click to expand...

@Doubeleive is the resident expert on the options.
@swathdiver is the resident Tech2 expert.

They will both recommend US sellers for the Tech2, and with good reason. But many have bought from here and its $220 right now.
http://www.chinacardiags.com/wholes...el-suzuki-isuzu-holden-with-full-package.html

as far as the drl's and dome light issue it sounds like you might have a short, the drl's should only be disabled if you press the dome light button 4x or 3x I don't remember which then it will go back to normal when you shut the key off, I would check the dome light harness for broken or pinched or possibly grounded out wire/s
this is probably your best resource for the wiring diagram
https://www.gmupfitter.com/files/media/photo/160/2000_LD_CKTruckNew.PDF
as was mentioned earlier a tech2 will be your best friend when troubleshooting they run about $300 on ebay for a clone, it will pay for it's self in short order since it is one time expense.

***keep in mind if you were not already aware the drl's will only illuminate when the truck is in drive and the parking brake is released.

if you have a windows tablet or a laptop with a standard usb port you can save a few buck and order a vx diag nano those run about $100-125 and it will give you tech2win (software based tech2 operation) and gsd2 software for most gm's that are 2014 or newer. (the tech2win will work from 96-2013), a tech2 hardware will go back to older years because it includes adapters for use before obd2