Cerveja
NAXJA Forum User
- Location
- SouthEast Michigan
I have a 2000 Cherokee with a Aisin AW4 Trans. I recently replaced the motor with a 4.7 Stroker, while the engine was out I sent the trans out for a rebuild because at 160,000 miles I didn't want to have to pull it a second time. Turned out it was a good idea cause the bell housing was cracked in multiple locations and needed to be replaced. When the New Bell housing, rebuilt trans and new motor were put in place, I started getting the infamous P-0720 Rear Output Speed Sensor error.
However the vehicle was driving fine in 4HI and 2HI, but in 4LO it would not shift out of first gear. The vehicle has since been back to the shop with the trans in place where he did all the usual continuity checks looking for a bad wire or short to ground and found nothing. I have swapped both the input and the output speed sensor front to rear and also with a donor trans of unknown origin and the fault does not follow the sensor. My trans guy is baffled since without a rear output sensor, he thinks that the trans should not shift out of first in either. I think the TCM is somehow getting a redundant signal from the T-Case and using that to compensate the missing signal from the Output sensor. He thinks the TCM is going bad which is why it's still managing to shift somehow but still throwing up the fault code.
I am curious if any one has been inside these transmissions to know what the Output sensor uses to get it's signal. Is there a dedicated tone ring on the output shaft that fires the sensor or does it just run off one of the other gears inside the trans? Is it possible this tone ring was not reassembled and that is why the signal isn't present? Could the trans have been improperly reassembled that the tone ring or gear is not aligning with the sensor and thereby not activating the sensor. The shop admitted they have not done many of the AW4 Transmissions because he thinks they are very reliable units nor has he had to replace to many TCM's for the same reason. I trust the shop as they have been in business for decades and the owner is a close personal friend who I believe to be honest, knowledgeable, and quite frankly; not out to rob me or any of his customers. So I am curious what is going on with the signal and where I look to repair it next. Any input is greatly appreciated.
However the vehicle was driving fine in 4HI and 2HI, but in 4LO it would not shift out of first gear. The vehicle has since been back to the shop with the trans in place where he did all the usual continuity checks looking for a bad wire or short to ground and found nothing. I have swapped both the input and the output speed sensor front to rear and also with a donor trans of unknown origin and the fault does not follow the sensor. My trans guy is baffled since without a rear output sensor, he thinks that the trans should not shift out of first in either. I think the TCM is somehow getting a redundant signal from the T-Case and using that to compensate the missing signal from the Output sensor. He thinks the TCM is going bad which is why it's still managing to shift somehow but still throwing up the fault code.
I am curious if any one has been inside these transmissions to know what the Output sensor uses to get it's signal. Is there a dedicated tone ring on the output shaft that fires the sensor or does it just run off one of the other gears inside the trans? Is it possible this tone ring was not reassembled and that is why the signal isn't present? Could the trans have been improperly reassembled that the tone ring or gear is not aligning with the sensor and thereby not activating the sensor. The shop admitted they have not done many of the AW4 Transmissions because he thinks they are very reliable units nor has he had to replace to many TCM's for the same reason. I trust the shop as they have been in business for decades and the owner is a close personal friend who I believe to be honest, knowledgeable, and quite frankly; not out to rob me or any of his customers. So I am curious what is going on with the signal and where I look to repair it next. Any input is greatly appreciated.