What does a tone ring do?

[Deleted member 69311]

How does the tone ring, that’s around the crank shaft, work? what does it tell the crankshaft position sensor, and if one broke, how do you replace it?


Mine broke and has been in the dealer for 6 weeks so I’m trying to understand why it’s taking so long. If it breaks again in the future, is it as simple as taking out the transmission, clutch, and replacing the tone ring, then reinstalling everything?

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[Cordero1]

I have no idea what it does. But last time I removed mine was because I was replacing the clutch & flywheel. Took me 1 week, & that was only working on it a bit at a time after work each day off my back on jack stands. Six weeks is crazy being that they are pros, have a lift, & all the help they need.

 

[Cobra Jet]

@GrayS550 here's info on both the Crank Sensor and Tone Ring.

The crank sensor needs the tone ring to relay firing commands back to the PCM. If either part is damaged (or if tone ring was left out during clutch reinstall), the car will not start.

- Crank sensor - failure can be the sensor itself, the harness to it or the pins in the connector. If the crank sensor is failing, it also will throw various misfire DTCs. The only time the crank sensor will throw a specific crank DTC is if the sensor is disconnected or it has completely failed. Many have found even with a generic misfire P0300, that the issue was related to the crank sensor. These sensors do not last forever due to their location and under hood heat cycles. Check this thread:
https://www.mustang6g.com/forums/threads/misfire-at-high-rpm.174380/#post-3531453

AND this one:
https://www.mustang6g.com/forums/th...e-sensor-tone-ring.156234/page-2#post-3197692

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See this thread for Tone ring info:
https://www.mustang6g.com/forums/threads/p06e9-dtc-no-start.150022/page-2#post-3066365

To inspect the Tone Ring for damages, it requires removal of the transmission.

See this thread; the first image in it, the round circular toothed object on the floor directly below the engine - that is the Tone Ring. It gets placed onto the back of the crank so the Crank Sensor can read it (also seen in the image):
https://www.mustang6g.com/forums/th...utch-install-and-flywheel-bolt-warning.87130/

 

[ice445]

The tone ring provides feedback to the crankshaft sensor. The raised spots in the ring come very close to a hall effect sensor (which has a magnet inside it), which induces a voltage change that the PCM reads. It's basically how the PCM knows where the crankshaft is in its cycle, and how it can calculate things like misfires/power balance. There's an expected time between pulses, if it is above or below this value it knows something isn't right.

So yeah, the tone ring has to come close enough to create a temporary magnetic field for the whole process to work. If you have any metal shavings stuck on the sensor, or the tone ring is worn down or something like that, the magnetic field will be weaker and won't create the necessary voltage change for the sensor to give a strong report to the PCM.

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