I have a 2007 chevy trailblazer ls with 4.2 l6 engine and 33,000mi and my fuel guage is on empty/alarm and i checked the check engine lite and it told me open fuel sending unit. i put a 20gal bottle of TECHTRON fuel additive to see if it will clean off sending unit. might have to wait and put another bottle in when tank needs filling again.I SEE LOTS OF OTHER COMPLAINTS TO GM ABOUT THIS TROUBLE

The 2004 is due for a transmission filter change. This should have been done at 60,000 miles, check your odometer reading.

First you need to have EBCM - electronic brake control module check for DTC'S - diagnostic trouble code's . If the light is on there is a code stored . I think most part stores can do this and for free . After you find out what code is stored , looking up that code in service repair information for diagnostic trouble shooting chart would be next step . There are a few codes too.
DTC C0035 or C0040
DTC C0045 or C0050
DTC C0110
DTC C0131
DTC C0161
DTC C0186
DTC C0196
DTC C0201
DTC C0240
DTC C0241 or P0856
DTC C0244 or P1689
DTC C0245
DTC C0283
DTC C0287
DTC C0290 or C0292
DTC C0455
DTC C0550
DTC C0558

Find the code do the diagnostic's , fix the problem , wiring issue's , a sensor , bad module ,what ever it is . The light will go out then . Here is a sample of code discription .
• DTC C0035 Left Front Wheel Speed Sensor Circuit
• DTC C0040 Right Front Wheel Speed Sensor Circuit

Nick, Fuel lines for your vehicle may come as an assy., if you want the OE lines. Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
PIPE. Fuel Line. This genuine part fits your 2006 Chevrolet TRAILBLAZER. PIPE,FUEL FEED & EVAP EMIS. Stock Code 25829656 ; 15922165 Manufacturer GM Categories Fuel System and Emissions > Other Assemblies FUEL SUPPLY SYSTE
FUEL SUPPLY SYSTEM LL8 4 2S for 2006 Chevrolet TRAILBLAZER
Chevrolet Fuel Lines
GM Fuel Lines eBay

****, you can check some more but from what I am reading your problem could be related to a faulty ignition switch. I am sending you a copy of some fixes.. you can compare to your condition..
Best of Luck to you..

2006 Chevrolet Trailblazer LS 4.2L, Vin S, Eng Cfg L6
Customer Concern: No blower motor function. AntiLock Brake System (ABS), Red Brake Warning Light (RBWL), Traction lights all on. Radio does not work. Tests/Procedures: 1. Check for battery voltage at fuses #31 and 39 in Rear Fuse Box under the rear seat.

2. If the voltage value is less than battery voltage, check the Orange wire at the 48 cavity connector located at the base of the steering column at pin D1.

3. If the voltage is low at C201 check the voltage at pin "G" of the ignition switch.


Potential Causes: Ignition Switch


2006 Chevrolet Trailblazer LS 4.2L, Vin S, Eng Cfg L6
Customer Concern: ABS, Low track light comes on intermittently. The heater blower motor quits running, 4WD not working. No communication with the ABS. If you disconnect the ABS computer and plug it back in, it may work. Tests/Procedures: 1. Test voltage at HVAC 30A, 4WD 15A, HVAC 1 10A, BRAKE 10A, TBC RUN 3A labeled fuses in the rear fuse block during the problem.

2. Inspect connector 101 38 cavity connector mounted along the underhood bussed electrical center. This harness may be routed tightly around the underhood fuse block, causing chafing or connector terminal contact that could induce any of the concerns listed.

3. Clean and secure ground G110 located on the lower left side of the engine block. Potential Causes: Damaged Circuit 300
Damaged Connector C101
Improperly Installed Engine Compartment Harness
Malfunctioning Ignition Switch

Check out the fuel level sensor, and or the guage itself. These guages do tend to out, can replace the little stepper motor on the back of it for cheap.

I would check my oil pressure gauge and the oil level as well. the fuel level guage also malfunctions on those models so make sure it is working properly and not floating from full to empty that will cause the light to come on as well as overheating of the engine(low coolant levels)low oil level,low fuel level,and low charging volts from your alternator.if all is well suspect a short in dash.

I had this problem as well. Took it to the garage and it was a $700 bill the part alone was $440 they had to drop the gas tank - and since then it's not been working right. The fan clutch went a week later another $700 bill. Picked it up and it was still making the same sound - garage replaced another sensor without charging me--picked it up and three days later the service engine light came on. Back to garage and another $80 part was needed under the hood. All this with just 52,500 miles and I keep it well maintained. Not a happy camper at all! Holding my breath but it's been only two days so far so good.

make sure there pluged in if so you need to get new ones

sounds like a bad ground in the wiring.

i have the same problem and it will cost to have it fixed.but right now we are using our trip odometer by 1st fulling up and refueling at 300 miles then resetting.as far as the check engine it could be as smple as a lose gascap. go to advance auto parts and ask them to check it.they will do it for free.if you buy the part from them you can take it back and they will clear your codes.hopes this helps you get by for a while