capezig

The needle just lays there, below the E...

After some resistance testing it appeared it was the fuel level sensor that had gone bad. Just finished dropping the tank and changing the fuel level sensor with no change in symptom...still dead and laying below the E. Is there any kind of reset needed to get the car to recognize the new sensor?

I have seen the idea to jump the terminals for the sensor at the plug under the drivers seat to test the gauge and all wiring on that side...any other thoughts at how to troubleshoot this would be greatly appreciated.

sergeimoskva

Hi !
One of the reasons for this - its the fuel level sensor in the gas tank gone bad . You said that the sensor is altered
The second reason...
Likely to it could be is the connection under the vehicle where the fuel pump connector hooks up. If you look under the van, on the drivers side, behind the drivers seat and in front of where the middle seat goes from under the van, You will see a junction block where 2 or 3 wire connectors plug up to. find the connector that has about 8 wires on it ( see photo ) and unplug it and make sure the connectors are not all full of corrosion up on it, If it is ok.


You can put a resistor in the fuel level sensor circuit and see if the gage follows the resistor type (Resistor 100 - 150 ohm) - see photo

capezig

So, after some more poking...using my Haynes wiring diagram and working at the plug under the van behind the drivers seat:

on the pigtail to the tank, 81 ohms between the purple and the black/white. added about 4 gallons of gas to what was in the tank and got 101 ohms. seems to indicate that the fuel level sensor and the wiring to the pigtail are ok. sensor better be ok as it is brand new.

in the body plug I find that the 5v reference voltage is present across the pins related to the purple and black/white. If I momentarily short the two I get the 'low fuel' warning message on the instrument panel, which would seem to indicate that everything from the pcm to the body plug under the car is ok, including the reading of this wire pair by the pcm.

needle on gauge does not move when ref voltage is shorted.

so I think I am down to a wire between the pcm and the gauge, or the actual gauge.

any thoughts?

sergeimoskva

Hi !
The resistance across the two wires at the connector beneath the driver's seat - it should be between 40-250 ohm depending on the level of fuel.
If everything test fine at that connector, go to the connector at the firewall beneath the dash. Measure the resistance there. If you measure the same as you did with the connector under the car, then your wiring is fine there. Otherwise, your problem lies between the two connectors.( It may be open broken wire under the left foot wire loom under the dash )
If the firewall connector is fine, check at the PCM. There is actually two connectors between the firewall and the PCM IIRC so a problem between the firewall and PCM could be between there. I can not put connectors pinouts - now I do not have.
Good luck to you!

capezig

If I short across the 5 volt ref voltage at the plug under the van behind the drivers seat, the low fuel light comes on. Logically, if that happens I would think the wiring from the plug to the pcm is intact, or it wouldn't read the fuel level reference voltage/resistance and give the output to the low fuel light. But when the 5v is shorted there is still no movement on the fuel gauge. Does anyone know the pin out for the instrument cluster to test the gauge independently...if that works then it has to be a wire between the pcm and the gauge...thanks for thinking about this...

capezig

fingers crossed, ordered new cluster. After realizing that some whacky operation on the temp gauge a while ago might be related, and just the cluster going away, bit the bullet and ordered a 'new' unit...will report back

sergeimoskva

Hi !
Perhaps your order cluster premature.
You can buy Stepper Motors for Cluster Repair Fuel Gauge and change the it yourself.
chevy venture fuel Stepper Motor | eBay
In any case - wish you good luck

capezig

The final chapter. We got a re-manufactured instrument cluster from Carid/Dorman. There was an issue with getting the programming to match up with the van. After the second try and a scan by a local garage to confirm the issue, vendor offered to pay for the programming to be sorted out at a local GM dealer. The experience at the dealer for my wife was not so great, but at least we are down to the end with this 'little' repair and just waiting on the core deposit and re-reimbursements.