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Discussion Starter #1
It's pegged way past empty. Mechcanic said it was the gauge but I replaced the gauge and it's still not working.

Checked wiring at the sending unit. It was in rough shape, the harness looked charred, green wire (ground?) broken off.

Does anyone know the color codes for the other four wires? I'm thinking the wire to the sending unit might be open.

The low fuel light still works. I'm selling the truck to my nephew and would like to fix this problem.
 

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I think you've found your problem, and you can get a free factory service manual from phatG20.net or several other places on the net.
 

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Discussion Starter #3
Thanks to a member of this forum I was able to find a wiring diagram for the fuel sending unit. Because the low fuel light still works, I'm hoping it's an open wire to the gauge.

But it doesn't make sense that the low fuel light and fuel gauge have separate wires from the sending unit unless they are two independent circuits. Good Japanese engineering but bad news for me.

I'm not going to replace the sending unit, I've lived with this for a long time by using the trip odometer but my nephew just got his license and probably won't be able to fill up every time he needs gas. I guess I'll include a pocket calculator with the truck.

I'll check the fuel sending unit this weekend and fix the ground wire. I'm keeping my fingers crossed.
 

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Discussion Starter #5 (Edited)
Just an update on my problem and a couple of questions.

First of all, I know why the mechanic thought the gauge was bad. If he was using the same manual I downloaded from the Internet, the troubleshooting procedure shows the wrong terminal on the guage to connect to ground for a full reading.

The sending unit is open for both the guage and the low fuel warning light so the low fuel light no longer works although I know it worked for a long time after the gauge went bad.

The green ground wire at the sending unit is broken from what appears to be corrosion. The harness and wires are charred but, obviously, the fuel pump still works.

A sending unit is a little over $100. I am considering replacing it but the charred wiring concerns me. There might be a short somewhere that caused the sending unit to burn out. I believe the sending unit comes with a new harness.

I tried to disconnect the harness but it proved difficult and given the condition of the wiring I did not want to damage it any further and lose power to the fuel pump.

I read on the Internet that the broken ground wire might have somehow caused the other wires to be overloaded and heat up, is this possible?

Also should I replace the sending unit or is it too risky? I'm selling the truck to my nephew and don't want him to run out of gas and now that I know the low fuel light doesn't work either I'm even more concerned. But I also don't want to throw away another $100 after already wasting $40 on a new guage.

I was thinking about using a part from a junkyard but seeing how corroded the unit is on my truck, I don't know if that's a good idea. Also should I consider replacing the fuel pump at the same time?

Normally, I would never do this kind of work on a 13 year old vehicle but it is in exceptional condition. With the exception of a alternator and starter, it has never had any problems. I'd like to see my nephew put another 100k on it.
 
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