On my gas tank underneath at the front top there is an access slot where 3 or 4 hoses come out the tank. you cannot see the top of the tank. There is a wiring harness that comes out and goes to a 4 prong connector. Can anyone verify what the 4 wires are. For example, it may be possible one of these wires goes to the gas gauge instrument panel. Also, it may be possible to measure the resistance of the sensor one one of these wires.

I would very much like to cut a hole above the tank for future access, but I have rear AC which is mounted under the rear bed. This pretty much eliminates getting a hole in there. I had an Isuzu which was great as you could remove a cap above the tank inside the vehicle to change the fuel pump or sensor.

 

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Don't understand why 2 fuel sensor wires. I will try to verify after unplugging that connector and measuring for 12 v. on one of the pins. I should be able to take a resistive reading at different levels of gas to see if the tank rheostat is working.

 

Because you need two wires to make a complete circuit.

 

I cut the hole for mine, I had paid way too much money too many times over the years to pay again. I dropped my tank, cut the hole, welded in some braces to have a solid and safe anchor for the screws that bolt the cover on. Murphys Law dictates now I will never have to replace my fuel pump again, laughing.

 

Because you need two wires to make a complete circuit.

Yes, of cousre you need 2 wires for a complete circuit, but not 4 on the connector depending on how they did it. You can use 3 wires.

You have the 12v source and ground which is always common. Those are the 2 basic wires. Now if the rheostat is wired from 12v to gnd and the center wiper for the resistance center tap were used for the gauge, only 3 wires are necessary. Since I don't have a diagram they may have two wires for the resistance souce which they probably do. This way only a variable resistance is needed, no actual voltage to the resistor.

I got around to ordering wiring diagrams for my Van since it is older and probably will encounter more use.

 

You know what they say about assuming!

The fuel level sensor circuit is not 12v like the pump is. The sensor circuit does not run directly to the gauge, it first goes to the PCM, then the PCM controls the gauge.

 

No offense that is the problem with guys like you. You assume because you have the diagrams everybody does. I just proved to you by a reasonable explanation why only 3 wires could have been used over why 4 were. I didn't say they were. Just showed how. By the way without a PCM. But your ego is the same as on many forums. I could tell by your very first response of checking the emergency brake. While you had a reasonable explanation for just saying that because of the ABS without explaining any logic also to the gas gauge. You do not explain your responses. I am 67 years old, retired, and have been in electronics all my life. Long before computers. In the old days if cars broke down, you fixed them quickly. Today you are charged a fortune to have a routine scan tool even reset a routine trouble fault that displays when there isn't even a trouble, just a routine trip to the dealer triggered by mileage that indicates a problem on the dash to scare people. Electronics in a vehicle are a wonderful thing and a home repair guys worse enemy.

The first really on-board computer controlled vehicle I had was in 1978. I had so many problems with the electronic ignition system in that truck it would break down on the road every 15,000 miles like clockwork. Even back then it was always $250 or $300 to repair every time. 5 electrical components in that
system (pickup coil, HEI, etc.) and they always insisted replacing every one of them. Since then I have seen my share of electrical circuit related problems in other vehicles. The probability of 5 in 5 failing was I am sure a billion to 1. I see so many newer vehicles broke down on the highways today, I can sure bet it is most always likely an electrical problem controlled by the circuits.

It is nice to have technology, but it is more about money. If they did it my way as I said it could have been checked and fixed it in 10 minutes, or you spend hours interpreting codes or following the stupid PCM logic and possibly replacing way too much. I have had many vehicles in my life, and the ones I had 50 years ago without this crap were just as reliable as today's with the proper maintenance.

That being said, this is a great forum, but you can tell the ratio of views to answers is really slim.

I had a Cummins TD Truck for 7 1/2 years, never had to put a penny in it. An accident stopped it, but it was an amazing truck. I would get over 12 mpg pulling a 10,000 lb. 34 ft. 5th Wheel

 

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Well then I guess I'm just holding you back by interfering with all of the other responses you have here to weed through. I'll leave you to them to find the answers you seek.