Patrick Campbell

My fuel level sender broke and I actually ended up trashing the whole "fuel tank module" anyway so I just want to make the light go off.

Anyone know how I can do this. I was thinking of tricking the level sender somehow (Tried grounding it out but I think it needs some voltage otherwise the PCM freaks out and makes it show empty anyway).

Per the FSM:
For diagnostic purposes, the 12V constant current source can only be verified with the circuit opened (fuel pump module electrical connector unplugged). With the connectors attached, fuel level output voltages will vary from about 0.6 volts at FULL, to about 7.0 volts at EMPTY. The variable resistor track is used to vary the voltage (resistance) depending on fuel tank float level. As fuel level increases, the float and arm move up, which decreases voltage. As fuel level decreases, the float and arm move down, which increases voltage. The varied voltage signal is returned back to the PCM through the sensor return circuit.

It sounds like if i found the right size resistor, that would do it but I can't seem to figure out. But not sure how to do it or what size resistor to use. I would put the resistor on the 12V line, and then on the other end of the resistor, ground it, right?

I guess I could also take the dash apart and take the bulb out but that is never fun...

dodgediesel4x4

Not sure the "correct way" of how to fix it, but I have heard of a few people just putting a little piece of black electrical tape over that part of their dash. Kinda redneck, but atleast you won't see that darn light anymore

Timmay2

I worked on a 1986 acura legend before.. the lady had every dash light on in it, with cardboard and duct tape covering them up.

cracked me up.

newriverSpecon

Not to ground. Between the "12V constant current source" and "sensor return circiut". Get a poteintiometer and you can adjust it instead of guessing.

Someone on here put in a capacitance probe that might be a good replacement alternative. Not sure of any of the details on it though.

Randy

Jeremy Cusick

Easiest way would be the electrical tape. You could also take the gauge cluster out and pull the bulb and its holder (put it in the glove compartment).

electrifried

A 240 ohm resistor between the fuel gage wire and ground should give a full reading all the time. Stewart Warner makes an adjustable universal unit for about 50 bucks. might be a way to fix yours.

Patrick Campbell

Hmm.

That is just the thing, the 12v supply IS the return circuit. There's only 2 wires. Ground and the constant 12v. Actually, according to the manual there's 2, but there are 4 on mine. I'm guessing I got some gas truck wiring, in which case (from the FSM):

Black is ground
Black/LB is sensor ground
Darkblue/WT is the sensor signal
Dark green/Black is the fuel pump relay output

The colors match up... and the Darkblue/White is +12v... any ideas?

jrs_dodge_diesel

Put the resistor between the Black/LB and the Darkblue/white. The sensor signal is the constant 12V line that goes to the fuel float. The fuel float moves a variable resistor. 12V goes to the resistor, depending on the resistance(fuel level) you will get a variable voltage off of it. As noted earlier 0.6V full tank, 7V empty. That variable voltage has to get sensed by the computer, it goes through the sensor return line or in this case its labeled SENSOR GROUND.

Patrick Campbell

Thanks JRS.... It is all good now. To me a ground is a ground, I was not thinking ground = return line that the gauge reads off of. Light == off for good.

jrs_dodge_diesel

Your welcome, glad it worked and the light is no longer an annoyance.