How many volts for fuel level meter?

[mtdineen]

The gas gage on my 2004 Vibe base is stuck at 1/2 tank all the time. I replaced the fuel level meter on the pump unit inside the tank and it still reads 1/2 tank even with a full tank. Does any one know how many volts there should be across the 2 wires going to the meter when the tank is full? I'm seeing 153 millivolts - seems to me it should be more like something between 1-5 volts.
Mike

[jolt]

To answer your question; I do not know. By the replies you have most people will not know. That is not how I would trouble shoot the fuel gauge problem. Since you changed out the sender then you still have the old one. What resistance (ohms) do you get from the old sender unit as you move the arm up and down? Do you get the same ohms from the new sender? Are the other gauges in the dash working as they should? If you hook up the old sender and move the arm up and down does the gauge work? Most gauges take the signal to ground. Bad connections, wiring, bad grounds are the most command problems. All connections must be clean and good grounds as you are dealing with low voltage and the system works off resistance. Another thing to check is the sender clearance in the tank. Can the float move freely all the way and down? Is the float stuck in the tank so that it does not move? As far as the electrical side of it, ohm out the wires, connections and make sure you have good grounds. If you had 1 to 5 volts voltage drop cross your gauge, you would have a burnt up, shorted out gauge. There should be very little voltage loss across the gauge. Stick with resistance and ohm the wiring from the gauge to the sender and from the sender to ground.

Good luck.

[mtdineen]

I've checked the resistance for the fuel level meter and the results are: 110 ohms down (empty), 6.5 ohms up (full) and changes as expected in between the two extremes. To add to the story, the "low tie pressure" symbol also resides in the same gage cluster as the fuel gage and it is always lit, regardless of actual tire pressure AND THIS CAR DOES NOT HAVE A TPMS.

How do I trouble shoot this? I'm wondering if the PCM is messed up? Ideas? Thanks!

[jolt]

Here some more information to check into:

https://www.repairprocedures.com/servic ... 17196.html
This site may have more information for a price. "Subscriptions start at only $5.00" and that is for 24 hours of access for what looks to be GM factory on-line manuals.

https://www.ar15.com/archive/topic.html ... &t=1037159
The guy here has info on troubleshooting the fuel gauge and he clams to work at a GM dealership. Follow "badhammer" info for troubleshoot and that is probably all you can do.

http://ricksfreeautorepairadvice.com/gas-gauge-wrong/
To somewhat back up the above link with the guy who works a GM dealership, this gives a general layout of how newer cars fuel gauge works.

I have read other posts about changing out dash cluster in Matrix (Vibe) and in most cases some part of the cluster does not work after the change. It needs to go to the dealership to have the cluster pulled and sent to the factory to be programed for that vehicle or something like that. Anyways, it does not look like anything cheap. Your ohm reading looks good and if you have checked all the connections and wiring to and from the tank, then it looks like the next stop is the dealership. Like I said before - good luck to you.