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Gas gauge wont work. Tried everything. 99 truck

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Old 05-24-2009, 11:14 PM
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Default Gas gauge wont work. Tried everything. 99 truck

On my gauge cluster after my truck died and i had to replace the fuel pump. I got in and the gas gauge, temp gauge, and cruise light doesnt work at all. not sure if battery gauge is working its certaily not moving but reading good volts.

The oil pressure speedo and tach all work fine. when i turn my cruise on it doesnt light up on my dash but works, but the tow haul lights up?

Seems to be half working,any ideas how i could fix it?

Also on the message center instead of it just reading low fuel it will flash the battery sign for a few seconds and then the low fuel and just keep doing it the whole time i drive.

Is it most likely the pcm? Ive tried everything new pump and sending unit,all fuses,new cluster.
Old 05-24-2009, 11:18 PM
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The sending unit in the gas tank is the problem. It is a common problem in the older nbs trucks.
Old 05-25-2009, 08:40 AM
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ive already replaced it twice. i can take my sending unit and put it in a friends truck and it will work.
Old 05-25-2009, 08:46 AM
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Have you tried a sweep test on the guages in your instrument cluster? Sounds like your cluster is fried.
Old 05-25-2009, 11:22 AM
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No but alot of the gauges still work fine. also i tried plugging in a new cluster that i know worked and it did the same thing.
Old 05-25-2009, 06:32 PM
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First thing I would do is take both battery cables off and let it sit a few minutes and then touch both cables together. This is the GM tech assist first attempt fix for weird situations like this. If it still isn't working right I would take the underhood fuse block up and make sure a mouse hasn't made a home under there. You could always see if its got some codes in it but for it to just die and need a fuel pump makes me think either the PCM is confused for some reason or you've got a mouse problem somewhere. All the gauges you mentioned are inputs to the PCM and the PCM outputs the value to the cluster. Sounds like its PCM related but I wouldn't condem it just yet.
Old 05-25-2009, 09:14 PM
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Not the fuse box for sure ive moved and check all that before. Im leaning towards the pcm since its the only thing i havent tried. will a simple re flash fix this? where can i get it done? rather not be the dealership
Old 05-26-2009, 12:30 PM
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Originally Posted by low87
Not the fuse box for sure ive moved and check all that before. Im leaning towards the pcm since its the only thing i havent tried. will a simple re flash fix this? where can i get it done? rather not be the dealership
Module programming for some unknown reason has been known to become corrupt and sometimes just a simple reflash can fix it. If you go to a dealer you will get a stock program flashed into it of course. Any tech that has a GM dealerworld login and password and a tech 2 can do it for you, it doesn't necessarily have to be done at the dealership. Otherwise I have no idea what your options are. Maybe get a performance tune while you're at it?
Old 05-26-2009, 12:47 PM
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Yea its like 120 to get a reflash might as well get a damn tune too
Old 05-26-2009, 11:22 PM
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yeah i got the same problem...its the sending unit. but the problem is way too expensive for me to fix right now


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