Question about 1996 GMC Sonoma
Is......the problem--"the gas gage reads empty when there is fuel in the tank. OR, The gage moves when the key to turned off ?
If it's the first,
You will need to test the gage and through process of elimination, determin if the Sending unit inside the fuel tank has gone Bad.
If its the second ? - Electrical gauges will move when powered down. Normal
Testing the gauge may not be easy - just depends on your ability.
It is a simple 2-wire gauge circuit, when disconnect (usually need the fuel tank) the gage reads in one direction (either full or empty)
then when shorted-the gage reads in oppisite direction.
Of course you must select the correct wires or you may short out the wrong circuits!! Most GM vehicles use a purple wire & black wire.
A quick method I have used to check the in-take part of the gauge is this.
1st. know there is gas - 1/2 tank works best.
2nd driver's door open, key in run position, engine not running.
3rd gently lift up on the door then let if come back down, gently.
just enough to cause the gas to slosh around.
4th - keep an eye on the gas gage, a bad sending unit in the take will show up as a "twitchy" needle.
Of course, if the gage never leaves empty - sloshing won't work.
I have a known good sending unit I can plug into the vehicle and simulate different levels of fuel - if the gas gage works, I know the problem is in the tank.
Let us know.
Posted on Mar 13, 2009
Shorted in tank sending unit. I personally have replaced over 200 of them. Dave Hamilton is correct in his advice . The newer gages won't always work like testing the old circuits. To properly test the fuel Gage itself you need a signal generator to send different amounts of resistance through the circuit. Just dis-connecting and then grounding the circuit won't work due to the fact that the ECM sees it as one thing and then converts it to another signal and sends it to the dash. MUD is right. Hope this helps. The sending units can be purchased without a fuel pump assy. so you can transfer it over. The tanks on these are really easy to do. If you have a splash shield , remove it. Take off the filler and return hoses. Disconnect the connector heading to the tank. Then with a deep socket take off the 2 straps and the tank will fall out. Try to empty the tank or drop it using a floor jack.
Posted on Jul 22, 2012
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Posted on Jan 02, 2017
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