Like Brian said there are two models of fuel level senders, one has 4 wires and the low fuel light sensor and one has 2 wires and no low fuel light sensor.

To test remove sender assembly from tank. Check for continuity across terminals 1 and 4 on plug. When the sensor is dry it should have continuity and when it is submerged in fuel it should have no continuity.


4 wire with low fuel light sensor (Low fuel sensor running N-E):



2 wire with NO low fuel light sensor:

mine didnt even look like the 4 wire one from the factory. i also swapped my gauges out for sr5 ones so i dont even know if it would work regardless. i know the stock gauges had a fuel light but idk about my current ones.

AFAIK my '86 dontn't even have a low fuel light....or I'm having the same problem. I even ran the tank dry once when I first got it....no 'Fuel Level Low' light.

It would have been nice tho... <img src="/forums/images/graemlins/notooth.gif" alt="" />

Nope, don't have 'em. Seems to me we didn't start having the fuel light available until 87-88; for non-SR5 at least.
I ran mine out on purpose just to see when I first got Ol' Blue (86). I believe that was what the 4th wire was for later on. That's a schematic trivia question. <img src="/forums/images/graemlins/smile.gif" alt="" />

Well my 86 does have it, and it's shown in the owners manual. It doesn't start to flicker until I've got roughly a gallon of fuel left in the tank.

Mmmmm well mine ran completly out(had to push it about a mile home good thing these 'yotas are so light) and it never came on...so I'm guessing I don't have one. Although there seems to be alot of places for idiot lights on the dash that don't do anything in mine.

My 85 didn't come with one and it came with the stupid lights. I put a sr5 cluster in there and them my gas gauge no longer worked. (Still haven't figured that one out yet) I can't tell you many times I've ran out of gas. So many I've lost count...but it doesn't matter cause I have a reserve on the back.

My brothers 87 sr5 came with the light. It never really was accurate though. sometimes you could would make it 20 miles before running out other times you make it 60 miles.

bottom line if you trust your gauge and think its right put gas in it when it reads E. The light aint worth sh1t

I know in mine, after 400KM it's time to look for the cheapest price gas station (have 10 litres left)

You can check your truck to see if it's got one by counting the wires off the sending unit. Two and it doesn't. More than two, and it does. As the system is rarely activated, it's going to be prone to failure from inactivity.

My fuel gauge drops to E when she gets down past 3/4 tank too, so I start looking for fuel at 200 miles. One of these days I'll replace the sender. Anyone happen to know the price on a gauge sender unit for an '88 sr5 p/u?