2004 Tahoe LT died while driving - SOLVED

[ohcrud]

Hi all.
Had to be towed to the garage that we've used for some years. They have always been good, honest.

The car just died, like flipping the ignition off. Trying to restart, the dash gauges would start up then just go to zero.
Wouldn't turn over.

This was 6 weeks ago. They still have it. Trying to troubleshoot an electrical issue, which is what they think it is. They think in the security system.

No codes. For background the car is at about 187,000 miles. Last summer the alternator was replaced.
We bought the car 5 years ago. Had to have the transmission replaced back then.
Once in a while there's short whistle, random, not loud, that seems to come from under the car.
But the car has always run strong and quiet.
Oh, also, the check engine light has been on since shortly after we bought it and had the transmission replaced, but everything always looked fine to the mechanics.

Any help would be appreciated. Also, can the security system be bypassed?

Thanks

 

[Big Mama]

What is the DTC for the check engine light? Many of these rigs have problems with the ground wires so I’d start there. 6 weeks is a long time to diagnose anything.

 

[strutaeng]

Find a different shop. 6 weeks to diagnose and they have 2 possible "we THINK it's XYZ"?! That's ridiculous.

I would imagine this is more or less a 3-4 hour diagnosis task. These vehicles are incredibly easy to work on. About as easy as it gets to be honest compared to any modern vehicle.

Edit: yes, the security system (VATS) can be disabled. Most online places that offer performance tunes can do this for a small fee. @BlackBearPerf is a tuner and a member here. Reach out to him.

 

[Doubeleive]

the check engine light has been on since shortly after we bought it and had the transmission replaced, but everything always looked fine to the mechanics
umm.........looked fine? lol

 

[Joseph Garcia]

I agree with the above comments, in that it is time to find another shop better versed in GM trucks. With a quality bi-directional scanner, you should be able to get very close to root cause of your issue without too much work. Then, the final determination of root cause can be identified by a quality mechanic.

Leaving the check engine light on and driving the truck is definitely not a recommended practice. 'Something' is triggering the light and should be diagnosed.

 

[Fless]

Would you clarify for us?

If by saying "it won't turn over" you mean that the engine won't crank, that's not a security issue. With only a security issue the engine would turn over and likely start, but die immediately. And I believe that you have a security light on the cluster; does it stay lit?

If "it won't turn over" means that it cranks but doesn't start, that's another thing.

Finally, if there's a Check Engine Light, there's a code that any decent scanner would show.

 

[rockola1971]

Would you clarify for us?

If by saying "it won't turn over" you mean that the engine won't crank, that's not a security issue. With only a security issue the engine would turn over and likely start, but die immediately. And I believe that you have a security light on the cluster; does it stay lit?

If "it won't turn over" means that it cranks but doesn't start, that's another thing.

Finally, if there's a Check Engine Light, there's a code that any decent scanner would show.

Yup. OP's mechanic isnt qualified to be a mechanic. Security system on our generation has nothing to do with the engine cranking over. If the Security system was activated (because its faulty) the engine would crank over. Depending on exact failure of the security system would determine the actual symptom of it because there are multiple stages within our security system starting at the key sensor then the BCM then the PCM and all associated wiring.

You can stick the old thandle screwdriver theft tool in our generations ignition and bust it and crank the engine over until the battery is dead if you want. The engine would start and run for approximately 5-10secs until the key sensor doesnt see a key in position and reports it to the BCM and the BCM tells the PCM to cut the fuel pump relay signal. Then the engine dies all while the security light is flashing.

This is why our generation doesnt care if you make a copy of the key at the local key store. Stick it in and it will work if the copy is close enough to original. The PASSLOCK security is just looking for a key to be present.

The OP's original symptom list wreaks of dirt/corroded/loose/broken ground or hot wire from battery or that hot terminal block on drivers side below the alternator.

 

[ohcrud]

What is the DTC for the check engine light? Many of these rigs have problems with the ground wires so I’d start there. 6 weeks is a long time to diagnose anything.

Sorry, what is a DTC

 

[ohcrud]

The engine doesn't crank. They said they have been checking all the wires.
For a couple of the weeks I don't think they did anything because they wanted the key fob to check the security system and it took me that long to get a ride to town from a neighbor. We live 30 miles away "in the middle of nowhere".
1 neighbor was sick, and when the other neighbor tried to start their truck, the battery was dead, so all 3 of us were stuck for a while.

A few weeks ago they thought it might need a new computer. But I haven't heard a followup.
And by the way I'm a 77 year old female, so the BCM PCM means nothing to me.

But I came here asking because I too was loosing confidence, and thinking they should have hasn't it by now....
You've all been helpful in telling me what they should have looked at.

I did read somewhere that it could be a corroded battery cable inside the insulation where it wouldn't be visible, but I thought they would surely know to check for that.....

 

[Big Mama]

Good for you for seeking another opinion. DTC’s are the codes that show up when they plug a diagnostic tool into the port that’s usually under the dash. In short it tells the mechanic where to look for problems.

The other abbreviations listed are for different control modules (your mechanics may have called them a computer) such as BCM or Body Control Module or others.

What would be helpful is if you can get the shop to tell you which codes they’re seeing.

You’re right about battery and ground cables causing these types of problems and your shop should know that but tell them anyway. Unfortunately it seems like you’re getting the run around. Do you have access to another shop?

 

[rockola1971]

I would immediately pull that vehicle from that shop and find another that has a reputation. Check google reviews, friends opinions, etc for a reputable shop.

While not impossible, the odds that your PCM is causing this problem are close to ZERO.

PCM --Powertrain Control Module (AKA engine computer)
BCM --Body Control Module (controls everything from interior lights to in the vehicle amenities and your security system inteface.
DTC --Diagnostic Trouble Code -- (AKA your check engine light is on and means a DTC is stored in the PCM)

 

[ohcrud]

2 things. Years ago when the check engine light came on we went right to the shop. They checked and there were no codes. I saw the code reader.
They said the check engine light can malfunction.

i was an Air Traffic Controller in the Marine Corps, and had a few emergencies where a chip warning light came on in a jet fighter, and it always turned out to be a malfunctioning warning light, so it seemed right that the check engine light can malfunction. That's why we didn't worry about it.
We later bought a code reader, and it also showed no codes.

I'll check tomorrow if there are any codes now, but if there were, I think it would have helped them diagnose.

If there's no progress tomorrow I'll have it towed to another shop, but I don't know how good they are. Many years ago I had a different car in that shop and was unimpressed, but one neighbor swears by them.

This shop has always been good, honest, and fast, until now., so I've been trusting them....

 

[shegarty]

The most likely cause of a fault like this is a bad ground - have them check the main engine block ground if they haven't already, it's behind the intake manifold close to the firewall

 

[ohcrud]

Well I talked to them today, they want to take it to the Chevy dealer.
They said the dealer has more specialized diagnostic tools than they do. Apparently there are problems in the computer itself that they can't fix. The codes aren't showing because the computers are damaged, and even if they bought new computers they would still have to get programmed by the dealer.

They have fixed problems they have found, but still stuff beyond their capacity. They think a short caused damage/more shorts to multiple systems, all at once.

We have had a good relationship with this place for years, and I have left it for so long because I know they are honest and aboveboard.

So, the saga continues. But I trust them more than a dealer.....

 

[ohcrud]

Just thought I'd pop in to update.
We got the car back on the 3rd. The dealer replaced the fuse box. Apparently messed up by mouse urine over the years. Our mechanic charged nothing for their time, and nothing for the two tows.

Thanks again for all of you who tried to help,

 

[SilverSport]

thanks for getting back and telling us the rest of the story...glad you are up and running again

Bill

 

[Big Mama]

I second that and be sure to take care of that mechanic. One’s like that are hard to find. Order pizza for them some day.