79 Low fuel Light check out?
Thread Starter
Melting Slicks
Joined: Mar 2003
Posts: 2,512
Likes: 49
From: Franklin IN
79 Low fuel Light check out?
We have a 79 that has the low fuel light. I have the dash all apart and I'd like to check out the low fuel light to be sure it works before I put the dash all back together. I have checked the bulb and that works fine. I don't know how to check the circut to see if it lights at the correct voltage. Since it works off the gauge it must read a certain voltage from the sending unit and turn the light on when the set point voltage is reached. Does anyone know what that is and how to test it? Thanks in advance for help with this.
Safety Car
Joined: Jun 2004
Posts: 4,374
Likes: 224
From: Beecher Illinois
Tested both my 79s just by running em low on gas. Knew I had only a little gas in the tank so I put a siphon hose in and took some out while it was running. Light lit up. Put the gas back in and it went out. Not too technical of a way to do it but it satisfied me.
Just so you know, it's easy to remove the fuel light/board just by pulling out the glove box. You can reach it from the opening.
Also, one of mine had a bad board. I had to solder a piece of wire where a little bit of the ribbon was missing. The other one was missing the board completely, and it's an untouched original 79 I've had since 84. Found one on ebay.
Mike
Just so you know, it's easy to remove the fuel light/board just by pulling out the glove box. You can reach it from the opening.
Also, one of mine had a bad board. I had to solder a piece of wire where a little bit of the ribbon was missing. The other one was missing the board completely, and it's an untouched original 79 I've had since 84. Found one on ebay.
Mike
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
We have a 79 that has the low fuel light. I have the dash all apart and I'd like to check out the low fuel light to be sure it works before I put the dash all back together. I have checked the bulb and that works fine. I don't know how to check the circut to see if it lights at the correct voltage. Since it works off the gauge it must read a certain voltage from the sending unit and turn the light on when the set point voltage is reached. Does anyone know what that is and how to test it? Thanks in advance for help with this.
Melting Slicks
Joined: Jul 2004
Posts: 2,577
Likes: 2
From: Long Island New York
Mine started acting weird yesterday. I started it up and everything was normal, the low fuel light was off with a 1/2 tank of gas. After the car was running for a while I came back to the car and noticed the low fuel light was on. I have never seen this come before except when I turn the key to the on position and then it goes out a few seconds later. I turned the car off and restarted it and it was still on. About 2 hours later I went out and started it and the light was off like it should be, however after it got back up to temp it came back on again. So I now have my own low fuel light issue to try and figure out. Sorry didn't mean to hijack your thread, I just figured while your getting answers here maybe someone can figure out both of our problems.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Mine started acting weird yesterday. I started it up and everything was normal, the low fuel light was off with a 1/2 tank of gas. After the car was running for a while I came back to the car and noticed the low fuel light was on. I have never seen this come before except when I turn the key to the on position and then it goes out a few seconds later. I turned the car off and restarted it and it was still on. About 2 hours later I went out and started it and the light was off like it should be, however after it got back up to temp it came back on again. So I now have my own low fuel light issue to try and figure out. Sorry didn't mean to hijack your thread, I just figured while your getting answers here maybe someone can figure out both of our problems.
Thread Starter
Melting Slicks
Joined: Mar 2003
Posts: 2,512
Likes: 49
From: Franklin IN
Mike,
Thanks for your reply. You have helped me out a lot I guess I never thought about the fact that it was by grounding the third terminal that it turns the bulb on. I'm going to try it next week and see if I can make it work. At the same time with every thing hooked up there should be a wire in the the harness from the tank that should do the same thing. So a simple test would be to ground that wire at the tank connection the light should come on. If my suspisions are correct the sending units are the most likely thing to go bad besides the bulb. Thank you for including your diagram.
Bob
Thanks for your reply. You have helped me out a lot I guess I never thought about the fact that it was by grounding the third terminal that it turns the bulb on. I'm going to try it next week and see if I can make it work. At the same time with every thing hooked up there should be a wire in the the harness from the tank that should do the same thing. So a simple test would be to ground that wire at the tank connection the light should come on. If my suspisions are correct the sending units are the most likely thing to go bad besides the bulb. Thank you for including your diagram.
Bob
