'97 TJ, I6
Superficially the same problem as this thread, but the usual diagnostics say that everything's working correctly except the reading itself:
The dash reads about half of what a mechanical gauge does, and like the other thread, the dash often drops to zero once it's fully warmed up and trips the alarm, when the mechanical one still reads just fine. I've also replaced the sensor with no effect. I've even tapped into the wires and run a datalogger on it, and it is in fact reading proportionally. The fast changes track engine speed, and the longer trend follows temperature, exactly as expected. And still a good-looking signal on the wire, even when the dash is zero.
So I've put a tee fitting and plug on the plumbing side (1/8" NPT), so I can have both working at the same time. And I'm looking at putting some electronics between the sensor and the wiring harness, to read the sensor, fudge it to match the mechanical gauge, and send that to the dash. Once I like it, I can take the mechanical one off and put the plug back in. Keep the tee, in case I need to check it again.
I'm not ready to make anything else permanent yet, so I'd really like an extension wire that I can cut up. So if it ends up not working, I can take the extension out and plug it back in direct like it is now. I have non-waterproof connectors to do that in the middle of the wire, but I'd rather stick with the original waterproof one if I can. There are lots of plugs to go on the end of the wiring harness and stick into the sensor, but I can't seem to find anything in any form that mates with it, except for the sensor itself.
Any ideas?
—-
Once I have that, the next thing is going to be switched 12V power to run the electronics. The two wires that go to the sensor appear to be a solid ground and a signal, which is pulled to +5V through about 250 ohms. Similar to some 4-20mA current loop sensors that I had on some industrial projects. Pulling it down towards ground, with varying strength, directly affects the reading on the dash.
No explicit power is required for that at the sensor, but my added electronics do need power. Only about 40mA or so, but that's still enough to drain the battery after a while, so it has to be switched. Where's a good place to find it?
Superficially the same problem as this thread, but the usual diagnostics say that everything's working correctly except the reading itself:
The dash reads about half of what a mechanical gauge does, and like the other thread, the dash often drops to zero once it's fully warmed up and trips the alarm, when the mechanical one still reads just fine. I've also replaced the sensor with no effect. I've even tapped into the wires and run a datalogger on it, and it is in fact reading proportionally. The fast changes track engine speed, and the longer trend follows temperature, exactly as expected. And still a good-looking signal on the wire, even when the dash is zero.
So I've put a tee fitting and plug on the plumbing side (1/8" NPT), so I can have both working at the same time. And I'm looking at putting some electronics between the sensor and the wiring harness, to read the sensor, fudge it to match the mechanical gauge, and send that to the dash. Once I like it, I can take the mechanical one off and put the plug back in. Keep the tee, in case I need to check it again.
I'm not ready to make anything else permanent yet, so I'd really like an extension wire that I can cut up. So if it ends up not working, I can take the extension out and plug it back in direct like it is now. I have non-waterproof connectors to do that in the middle of the wire, but I'd rather stick with the original waterproof one if I can. There are lots of plugs to go on the end of the wiring harness and stick into the sensor, but I can't seem to find anything in any form that mates with it, except for the sensor itself.
Any ideas?
—-
Once I have that, the next thing is going to be switched 12V power to run the electronics. The two wires that go to the sensor appear to be a solid ground and a signal, which is pulled to +5V through about 250 ohms. Similar to some 4-20mA current loop sensors that I had on some industrial projects. Pulling it down towards ground, with varying strength, directly affects the reading on the dash.
No explicit power is required for that at the sensor, but my added electronics do need power. Only about 40mA or so, but that's still enough to drain the battery after a while, so it has to be switched. Where's a good place to find it?
