Jeffery Moon
Registered User
Hey guys. I have a 93 f250 7.3 idiot. My tach quit. Checked for power to the sensor with no result. How does the tach sensor get it's power.
Tach not working. No power to sensor
- Thread starter Jeffery Moon
- Start date
gandalf
Senior Member
The tach sensor? Do you mean that bolt-like thing on the IP gear tower, about a 1 inch bolt with 2 wires? I wasn't aware it needed power, that it received power from some source.
Those tach "sensors" don't have an unlimited life. They will eventually die. There is one thing you can do before you rush out to buy a new one. Disconnect the 2 wires (I think they each have a spade connector within a foot of the sensor), pull the sensor out of the gear tower, and clean it. Wipe it down well. Be sure that the end opposite the wires is very clean, and reinstall it, reconnect the wires. If the tach works consider that a warning and start looking for a new sensor. Your sensor is on it's last legs. If your tach still doesn't work then it's time to rush out and find a new one.
There could be other causes, but I've given you the first and the easiest. You probably don't want to tear your dash apart to check wiring behind it. I've never done that, so I can't instruct you on the procedure.
Those tach "sensors" don't have an unlimited life. They will eventually die. There is one thing you can do before you rush out to buy a new one. Disconnect the 2 wires (I think they each have a spade connector within a foot of the sensor), pull the sensor out of the gear tower, and clean it. Wipe it down well. Be sure that the end opposite the wires is very clean, and reinstall it, reconnect the wires. If the tach works consider that a warning and start looking for a new sensor. Your sensor is on it's last legs. If your tach still doesn't work then it's time to rush out and find a new one.
There could be other causes, but I've given you the first and the easiest. You probably don't want to tear your dash apart to check wiring behind it. I've never done that, so I can't instruct you on the procedure.
ih8minimumwage
Full Access Member
The tach sensor doesn't have power to it. It's a magnetic pickup that creates a signal off of the gear teeth.
Being a magnet, it will collect every bit of metal in your oil and not be able to send a signal. As gandalf said, remove your sensor and clean the end off.
Being a magnet, it will collect every bit of metal in your oil and not be able to send a signal. As gandalf said, remove your sensor and clean the end off.
Digger Smolkin
Registered User
If your truck has an E4OD, check the 20A maxi fuse under the hood for your TCM. The signal from the tach sensor goes to the TCM and then to the tach gauge. I know this because I am currently blowing that fuse every few days and still investigating why...
If you have a manual trans then you don't need a tach. I hear some people have had good luck with the Dorman replacements if a JY part isn't in the cards. I tried cleaning mine but no luck--then about 1.5 years later the tach started working again but only for a few months.
Also not needed for C6. My 85 E350 has the port plugged in the timing gear cover because vans before 92 never got tachs. My 87 F250 has C6 with tech but the sensor is bad. Doesn't matter though, since it has nothing to to with the transmission.
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