Atlas75 Posted November 26, 2021 Author Share Posted November 26, 2021 Oil and fuel gauges work as they should. On the aftermarket gauge I installed, I did not use any pipe tape and the only power needed is to run the back lighting if needed. This particular gauge has the ether filled line from sender to gauge. I have not done anything to the factory sender. I did find a troubleshooting guide in my 1980 EVTM but have yet to perform the test. I will also try grounding the wire on the sender to see if the gauge moves. Well if the after market gauge is a mechanical there is no reason why it should not work Unless it is not in water to pick up the heat? Boil a pot of water and dip the sender in it and see if it moves. If not bad gauge. On the factory grounding the wire is the easiest way. If you have a test light you can put it on the wire and to ground and it should blink if all is good back to the cluster. They say you can also swap the oil & temp wires on the senders as the gauges are the same just marked oil & temp but work the same. My factory oil gauge stopped working today just have not done the testing to see if gauge (hope not) or the 2 year old sender. Dave ---- I had a few moments today so I tested the gauge as you suggested. My test light blinked in a consistent pattern when connected to the factory wire. I also grounded the wire and turned on the key and the gauge moved. So I think I am down to a bad sender or the connection between the sender and the factory wire (which is not to pretty). Is there a resistance range that the sender should measure depending on the heat of the coolant? Link to comment Share on other sites More sharing options...
Atlas75 Posted November 26, 2021 Author Share Posted November 26, 2021 I had a few moments today so I tested the gauge as you suggested. My test light blinked in a consistent pattern when connected to the factory wire. I also grounded the wire and turned on the key and the gauge moved. So I think I am down to a bad sender or the connection between the sender and the factory wire (which is not to pretty). Is there a resistance range that the sender should measure depending on the heat of the coolant? I forgot I also had a question. You can see the new unit mounted on top of the thermostat housing…which is on the radiator side of the thermostat. My question is in regards to the blocked off port that is to the left and down on the intake manifold. Does anyone know if that is coolant? That would be a better place for the aftermarket gauge. Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 26, 2021 Share Posted November 26, 2021 I had a few moments today so I tested the gauge as you suggested. My test light blinked in a consistent pattern when connected to the factory wire. I also grounded the wire and turned on the key and the gauge moved. So I think I am down to a bad sender or the connection between the sender and the factory wire (which is not to pretty). Is there a resistance range that the sender should measure depending on the heat of the coolant? Yes 10 to 72 ohms. Link to comment Share on other sites More sharing options...
Atlas75 Posted November 27, 2021 Author Share Posted November 27, 2021 Yes 10 to 72 ohms. I took a meter to the engine temp sending unit today. I let the engine warm up just a bit and then shut the motor off and measured the resistance. Looked to be a bit over 2M ohms. I think a new sending unit is in my future as that is no where near a range of 10 to 72 ohms. Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 28, 2021 Share Posted November 28, 2021 I took a meter to the engine temp sending unit today. I let the engine warm up just a bit and then shut the motor off and measured the resistance. Looked to be a bit over 2M ohms. I think a new sending unit is in my future as that is no where near a range of 10 to 72 ohms. I think you've found it. Link to comment Share on other sites More sharing options...
Atlas75 Posted November 28, 2021 Author Share Posted November 28, 2021 I think you've found it. Quick radio question. My truck has a Motorola radio. Not sure if it is original or even a ford radio. It is model 5F3RMX8. My question is in regards to the connections. It has 3 wires (not including speakers). A white, a white with red strip and a black. The black is cut so it is not doing anything. How should it be connected? Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 28, 2021 Share Posted November 28, 2021 Quick radio question. My truck has a Motorola radio. Not sure if it is original or even a ford radio. It is model 5F3RMX8. My question is in regards to the connections. It has 3 wires (not including speakers). A white, a white with red strip and a black. The black is cut so it is not doing anything. How should it be connected? That model # doesn't show up in the master parts catalog, so I don't know anything about it. And the wire colors don't match anything in the 1981 EVTM, although I've not looked at the 1980 EVTM. But I'd bet the black wire is ground and the white or white/red is switched power and always-on power, or vice versa. I would pull that cover and see if it looks like the black wire goes to the chassis. Or use a DVM to check that. If so I'd put power to both white and white/red and speakers to the others and see if it works. If so, then experiment to see if white or white/red is switched. Link to comment Share on other sites More sharing options...
Atlas75 Posted November 29, 2021 Author Share Posted November 29, 2021 That model # doesn't show up in the master parts catalog, so I don't know anything about it. And the wire colors don't match anything in the 1981 EVTM, although I've not looked at the 1980 EVTM. But I'd bet the black wire is ground and the white or white/red is switched power and always-on power, or vice versa. I would pull that cover and see if it looks like the black wire goes to the chassis. Or use a DVM to check that. If so I'd put power to both white and white/red and speakers to the others and see if it works. If so, then experiment to see if white or white/red is switched. Why would you need an unswitched supply to a dial radio? Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 29, 2021 Share Posted November 29, 2021 Why would you need an unswitched supply to a dial radio? Good question. So, one is probably illumination? Link to comment Share on other sites More sharing options...
Atlas75 Posted November 29, 2021 Author Share Posted November 29, 2021 Good question. So, one is probably illumination? Good thought! I’ll try to test for that. And I did learn that that model radio was used in Ford vehicles up through 1978. Link to comment Share on other sites More sharing options...
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