Hodakaguy
Adventurer
Gauges - 2nd time's a charm! Getting the Temp & Fuel gauge working again on the 40! And lets not forget that oil pressure gauge.
After cleaning the connections on the circuit board last time the fuel & temp gauge started working again....for a bit. On the first drive the gauges quit again shortly into the drive...came back on....then quit again. Time to investigate.
After some internet sleuthing it looks like the voltage regulator on the back of the fuel gauge is the most likely culprit. Time to take the gauge cluster back apart again.
Disassembled. Now that the gauges are out of the housing I can inspect the suspect Fuel Gauge.
The fuel gauge is supplied by 12v that feeds a built in voltage regulator, the voltage is then reduced to 6v to run both the fuel gauge and temperature gauge. If the regulator is malfunctioning both the fuel and temp gauges will stop working. The regulator is a bi-metallic unit and when current flows through the regulator the unit heats up, expands and opens a set of contacts breaking the circuit, it then cools down again the closes the contacts. This cycle is continuous and the average voltage equals 6v.
The rear of the fuel gauge.
Here you can see the voltage regulator (The U shaped flat metal piece) and it's contact points. If these points get dirty over the years the regulator can stop functioning correctly (see Below).
Testing the voltage regulator: I tested my regulator and found that is was performing inconsistently. I ended up dressing/cleaning the contact points and the unit re-tested nice and consistent. Perfect!
Video showing the testing procedure in action along with a better description of the voltage regulator.
The test setup.
Back together we go.
Now to get the original oil pressure gauge up and running. I grounded the sensor wire under the hood and powered on the gauges with the key....the oil pressure gauge went all the way to High.... Perfect! The gauge itself is working! Next up I removed the tubing that runs to the aftermarket mechanical gauge that the previous owner installed and installed a proper new oil pressure sending unit in it's place. I ended up completely removing the mechanical oil pressure gauge and tubing.
Video of the oil pressure gauge testing process:
Yeah buddy....all the gauges working great now! Drove around a good portion of the day and they all operated smoothly and consistently. Nice having all the OEM gauges working!
Hodakaguy
After cleaning the connections on the circuit board last time the fuel & temp gauge started working again....for a bit. On the first drive the gauges quit again shortly into the drive...came back on....then quit again. Time to investigate.
After some internet sleuthing it looks like the voltage regulator on the back of the fuel gauge is the most likely culprit. Time to take the gauge cluster back apart again.
Disassembled. Now that the gauges are out of the housing I can inspect the suspect Fuel Gauge.
The fuel gauge is supplied by 12v that feeds a built in voltage regulator, the voltage is then reduced to 6v to run both the fuel gauge and temperature gauge. If the regulator is malfunctioning both the fuel and temp gauges will stop working. The regulator is a bi-metallic unit and when current flows through the regulator the unit heats up, expands and opens a set of contacts breaking the circuit, it then cools down again the closes the contacts. This cycle is continuous and the average voltage equals 6v.
The rear of the fuel gauge.
Here you can see the voltage regulator (The U shaped flat metal piece) and it's contact points. If these points get dirty over the years the regulator can stop functioning correctly (see Below).
Testing the voltage regulator: I tested my regulator and found that is was performing inconsistently. I ended up dressing/cleaning the contact points and the unit re-tested nice and consistent. Perfect!
Video showing the testing procedure in action along with a better description of the voltage regulator.
The test setup.
Back together we go.
Now to get the original oil pressure gauge up and running. I grounded the sensor wire under the hood and powered on the gauges with the key....the oil pressure gauge went all the way to High.... Perfect! The gauge itself is working! Next up I removed the tubing that runs to the aftermarket mechanical gauge that the previous owner installed and installed a proper new oil pressure sending unit in it's place. I ended up completely removing the mechanical oil pressure gauge and tubing.
Video of the oil pressure gauge testing process:
Yeah buddy....all the gauges working great now! Drove around a good portion of the day and they all operated smoothly and consistently. Nice having all the OEM gauges working!
Hodakaguy
