barsteel
Member
Hello!
Here's the situation. Neither the temp or fuel gauge on my '65 Fury III worked when I got the car. I finally dug into it a few days ago, but have not had success. Here's a summary of where I am without going into excruciating detail about all the hours I've spend on trying to get these gauges to work. When I started, neither gauge worked...
First, I pulled the gauge pod and gently sanded all of the contacts on the printed circuit board, re-soldered the 4 pins on the board for the socket connector, gently sanded the pins to remove any oxidation, retightened all of the terminals in the socket by slightly crimping/crushing them, wire brushed all of the mounting terminals for each gauge, cleaned each nut, and reassembled everything tightly.
When I reinstalled the gauges and turned on the key, both gauges pegged, and the temp gauge started to smoke. I immediately disconnected everything and decided to start with the temp gauge.
I read the manual and decided to run some tests. The voltage step-down control in the fuel gauge that feeds the temp gauge jumps between 1 and 7 volts, so it appears as if it works (per the manual). I have continuity through the circuit board to the temp gauge, so I know that the temp gauge is getting current as it should. I disconnected the temp sending unit wire at the water pump and checked for a short in the wire at the socket end, and there was none; no current would pass through the wire when it was disconnected, and current flowed when it was connected. Lastly, the sending unit showed about 78 ohms with the engine slightly warm. I believe that the resistance range should be 25 - 152, so the unit appears to be working. So...the temp gauge it getting the correct current, there's no short in the wire to the sensing unit on the engine, and the sensing unit appears to be in line. Seems like a bad gauge(?).
Onto the fuel gauge. It was getting about 14v through the socket. The wire in the socket going to the gas tank sending unit measured about 72 ohms resistance. I can't find the spec in the manual, but at least I know that it's not infinite resistance. So, I know that the gauge is getting power and it seems as if the sending unit is not bad, although I haven't dropped the tank to test it.
Here's the rub...during the 100 or so times I had the gauges out, if I held the gauge pod and tilted it forward, putting some pressure on the harness, they would work...kind of...for 30 seconds or so. The fuel gauge would move to full, or halfway there (I have about half a tank of fuel), and the temp gauge would be to maybe 1/4 hot...then it would go to cold. YES, I had the gauge pod grounded. Sometimes they would work, and sometimes they wouldn't, other times one and not the other.
To see if there might have been a break in the harness, I put test lights into the sockets that feed the gauges and gauge lights, jiggled the harness behind the dash, but I still got steady power, so it doesn't appear as if there are any breaks in the harness.
NOTE - the car is a fresh repaint, so I ran additional grounds from the negative battery terminal to the frame and to the firewall to assure that I had a good ground all the way through the car. I also cleaned all of the contacts in the fuse panel and on the back of the fuse panel.
So...I have gauges that "kinda" work when you hold them in a special way. Everything else is seemingly in order. The manual tells how to test the gauges, but they use a special tool that I don't have. I did feel 12V to the power terminal on the fuel gauge, grounded the housing, then grounded the terminal going to the sensor, and the gauge pegged full. Seems like it works???
Any ideas what's going on? I had to walk away for a day 'cause it's frustrating the hell out of me.
Thanks...
Chris
Here's the situation. Neither the temp or fuel gauge on my '65 Fury III worked when I got the car. I finally dug into it a few days ago, but have not had success. Here's a summary of where I am without going into excruciating detail about all the hours I've spend on trying to get these gauges to work. When I started, neither gauge worked...
First, I pulled the gauge pod and gently sanded all of the contacts on the printed circuit board, re-soldered the 4 pins on the board for the socket connector, gently sanded the pins to remove any oxidation, retightened all of the terminals in the socket by slightly crimping/crushing them, wire brushed all of the mounting terminals for each gauge, cleaned each nut, and reassembled everything tightly.
When I reinstalled the gauges and turned on the key, both gauges pegged, and the temp gauge started to smoke. I immediately disconnected everything and decided to start with the temp gauge.
I read the manual and decided to run some tests. The voltage step-down control in the fuel gauge that feeds the temp gauge jumps between 1 and 7 volts, so it appears as if it works (per the manual). I have continuity through the circuit board to the temp gauge, so I know that the temp gauge is getting current as it should. I disconnected the temp sending unit wire at the water pump and checked for a short in the wire at the socket end, and there was none; no current would pass through the wire when it was disconnected, and current flowed when it was connected. Lastly, the sending unit showed about 78 ohms with the engine slightly warm. I believe that the resistance range should be 25 - 152, so the unit appears to be working. So...the temp gauge it getting the correct current, there's no short in the wire to the sensing unit on the engine, and the sensing unit appears to be in line. Seems like a bad gauge(?).
Onto the fuel gauge. It was getting about 14v through the socket. The wire in the socket going to the gas tank sending unit measured about 72 ohms resistance. I can't find the spec in the manual, but at least I know that it's not infinite resistance. So, I know that the gauge is getting power and it seems as if the sending unit is not bad, although I haven't dropped the tank to test it.
Here's the rub...during the 100 or so times I had the gauges out, if I held the gauge pod and tilted it forward, putting some pressure on the harness, they would work...kind of...for 30 seconds or so. The fuel gauge would move to full, or halfway there (I have about half a tank of fuel), and the temp gauge would be to maybe 1/4 hot...then it would go to cold. YES, I had the gauge pod grounded. Sometimes they would work, and sometimes they wouldn't, other times one and not the other.
To see if there might have been a break in the harness, I put test lights into the sockets that feed the gauges and gauge lights, jiggled the harness behind the dash, but I still got steady power, so it doesn't appear as if there are any breaks in the harness.
NOTE - the car is a fresh repaint, so I ran additional grounds from the negative battery terminal to the frame and to the firewall to assure that I had a good ground all the way through the car. I also cleaned all of the contacts in the fuse panel and on the back of the fuse panel.
So...I have gauges that "kinda" work when you hold them in a special way. Everything else is seemingly in order. The manual tells how to test the gauges, but they use a special tool that I don't have. I did feel 12V to the power terminal on the fuel gauge, grounded the housing, then grounded the terminal going to the sensor, and the gauge pegged full. Seems like it works???
Any ideas what's going on? I had to walk away for a day 'cause it's frustrating the hell out of me.
Thanks...
Chris
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