Need help Shaun, an 07 Trailblazer issue


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Yesterday when I took the vehicle out I had at least a 1/4 tank of fuel. Hoping to gas up at my destination in Connecticut. 15 minutes into the trip the low fuel warning light came on. I knew I had fuel, so I continued the trip. Gassed up as soon as I got there, a 65 mile ride from the start. The tank took about 16 gallons so I guess I needed fuel. With a full tank the fuel gauge did not show a full tank, matter of fact it kept reading empty with the low fuel warning light on. We got to where we were going and I parked the vehicle and it stayed put for about 5 hours. When I started the truck up to leave, not only did the low fuel light stay on and tank read empty, now I have the engine warning light lit. The truck ran fine with no signs of malfunction on the way home.

If the sending unit went bad, could that be cause for the engine light to be lit? Would fuel with water in it/bad gas cause this issue making the sending unit freeze? It has been quite cold here.

I am going to try to get a appt with the Chevy dealer for service this week. It is still covered under the GM warranty.

Any insight would be appreciated.

Thanks in advance.

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Gonna be interested in hearing Shaun's reply here Anthony. First thought as reading was a stuck sending unit, but reading further would think that is probably not the case. If I were guessing I would guess it might be a connection somewhere, kinda with you on the line of thinking that if the sending unit were bad it should not light the check engine light. Glad it is under warranty for you.

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It's hard to say Anthony. My GM site is down right now so I can't check the wiring schematics to verify my thoughts. Usually with an open circuit for the fuel level sensor it reads full all the time, and a short to ground reads E all the time. Could be wiring or right inside the sensor itself. Check engine light will more than likely be the code for the screwy readings from the fuel level sensor.

At least it's still under warranty. :)

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Sounds like the sensor itself to me Anthony. Fairly common thing. Hopefully they have the parts in stock and can get you in and out in one day. Only a couple hour repair.

Think you are right on the fuel level sensor being faulty, Shaun. The MIL could be on because the ECM recognized the failure. The level sensor is tied directly to the Evaporitive emission control system in as much as the evap system won't run it's normal tests if the fuel tank is around under 25% or less full or around 85% or more full.

If I am not mistaken, the F.L.sensor can be replaced seperately from the fuel module. This isn't true on all models though. The gas tank has to be removed, depending on how many miles there are on the vehicle, you may want to replace the whole module. If it were me and the vehicle had over 100,000 miles I would replace the whole module. If there is a warranty involved you might be able to pay the difference between the module and sensor " out of pocket ". This you will have to work out with the dealer and/or the warranty company. A fuel pump failure in a few more miles would require removing the tank again. I don't know your circumstances so I am just throwing this out there. Could be a cost savings down the road in labor costs.

Never is easy is it?

Lynn

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Thanks for the advice Shaun :). I really appreciate it. Wife was worried to drive it and I afraid she might get stuck with the electronics acting funny.

The vehicle has only 34k on it so it is relatively new still under the factory GM warranty.

Do they put the gas back in if they have to drop the tank? I just filled it up yesterday dropping $65.

Lynn, thanks for the advice I will go over that with the repair mgr at the dealer.

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We don't take any gas out unless absolutely necessary. In some cases we use the gas guzzler to suck some out once we get the tank down to ease putting it back in. Then put it back in once the tank is back in the vehicle. The less gas in the tank makes our lives more easy to drop the tank down and replace the sensor. Don't lose sleep over taking it in full though.

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Thanks for the advice Shaun :). I really appreciate it. Wife was worried to drive it and I afraid she might get stuck with the electronics acting funny.

The vehicle has only 34k on it so it is relatively new still under the factory GM warranty.

Do they put the gas back in if they have to drop the tank? I just filled it up yesterday dropping $65.

Lynn, thanks for the advice I will go over that with the repair mgr at the dealer.

Oh yes, they'd put the gas back in. We like to pump it out if we can just to make the tank easier to handle. The mfgs. don't have brains enough to provide drains on the tanks!

As far as driving, I wouldn't worry about the MIL while waiting for an appointment unless it is flashing. Don't take me wrong here though. I don't recommend anybody driving around with a MIL lamp on. You could have a minor problem which illuminated the lamp, ignore it and if a more serious problem arises you would not know it as the lamp was already on. The lamp is there for a purpose. Always err on the side of caution.

With the mileage you have, I wouldn't change the whole module unless they cover it under the warranty or if that is the only way the sensor is available. That would be up to the dealer.

As a word of caution, I would estimate the mileage you have left on the gas in the tank and reset the trip odometer. Please don't fill it up on the way to the repair facility. If you have to wait a few days for repairs you want to be sure you aren't going to run out of gas.

The technicians at the shop will appreciate your thoughtfulness, trust me.

Good luck,

Lynn

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The technicians at the shop will appreciate your thoughtfulness, trust me.

Good luck,

Lynn

Ditto. Always nice to be able to drop the tank less than 1/2 full. There's nothing worse than fighting a full tank. About as worse as getting into a vehicle to road test for a complaint rolling down the highway and the gas needle is in the red and low fuel light on.:bang:

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Ditto. Always nice to be able to drop the tank less than 1/2 full. There's nothing worse than fighting a full tank. About as worse as getting into a vehicle to road test for a complaint rolling down the highway and the gas needle is in the red and low fuel light on.:bang:

I hear ya! Never happens to me unless it is pouring or snowing to beat H--- outside. Now I am standing outside putting 5 gal. of gas in someone's vehicle who couldn't bother.

Same thing happens to me when a customer comes in for an Evap smoke and pressure test. We can't do a diagnosis until the tank is over 1/4 full. The bay test is aborted. Luckily, there is a station just up the hill. We advise folks coming in for this to run the tank down or fill it to 1/2 full before coming in. Think they listen? Guess again!

Lynn

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  • 2 weeks later...

OK Boys..here is a follow up to my 07 Trailblazer issue.

Truck went back to the dealer...there was some warranty issues. The salesman cleared all that up with the service dept. We are good with the GM warranty until 42kmiles or November 2011 because it is a GM certified vehicle.

The steering wheel position sensor was replaced.( what does that do?)

The wife said the light with the truck and wrench comes on occasionally.

Guess that was it.

The Fuel level sensor was also replaced. That explains the fuel level issues.

Thanks for the help Shaun and others!

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Glad they got you fixed up Anthony, good it was covered.

Question for Shaun here, is the level sensor essentially the same thing as a sending unit?

The sending unit is the whole assembly that goes into the tank. The level sensor is attached to the sending unit. Some vehicles you can just buy the sensor, some vehicles you need to get the whole sending unit.

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