ltmark
Member
I recently posted a question re: Expy speed sensor with no responses. I have resolved that since I discovered that the OSS is inside the trans on the LEADFRAME.
Problem: I have a 2012 Expy with the PCM update re: the car suddenly dropping into 1st gear! However, the car does suffer this problem every few days and goes into limp mode; I stop, turn off the engine and upon restart, all is good. It never did it until after the update was programmed into the PCM by the dealer. It has only thrown a code one time, being P0720 (output speed sensor).
I have a OBD2 scanner that is pretty good but does not have a reading for the OSS sensor. Recognizing that the TP sensor, APP sensor, TB motor etc etc all supply info to the PCM and could contribute to this issue, I have monitored all the OBD2 readings and can't locate any obvious data problems I have tired recording the data, but the scanner only records for about a minute, each time, and it;s never happened when I was recording. I have some data recordings that tend to show a possible accelerator (APP) issue, but not definitive and that seems to be an unlikely cause.
I would have already replaced the OSS sensor, but on this year model Expy, it's inside the trans and will cost approx 700.00 so, that's a bit much on a "maybe" solution.
After this long story, my question is: Does anyone know if a failing OSS sensor can cause a limp mode issue only occasionally and not throw a code when it fails? Also, are there any scanners that can show the OSS readings? My thought was to put a T-pin in the PCM OSS output pin, run wires into the cabin and try and monitor the signal as I drive, but that get a little dangerous on the streets of California???
Lastly, my TP_d sensor never goes above 78%, nor does my APP above 64%. My scanner doesn't show voltage, just %. I would think that they should go to 100% if I put the pedal to the floor?? Maybe these are issues that cause the PCM to have a conflict and go to limp mode????
Any comments would be appreciated.
Problem: I have a 2012 Expy with the PCM update re: the car suddenly dropping into 1st gear! However, the car does suffer this problem every few days and goes into limp mode; I stop, turn off the engine and upon restart, all is good. It never did it until after the update was programmed into the PCM by the dealer. It has only thrown a code one time, being P0720 (output speed sensor).
I have a OBD2 scanner that is pretty good but does not have a reading for the OSS sensor. Recognizing that the TP sensor, APP sensor, TB motor etc etc all supply info to the PCM and could contribute to this issue, I have monitored all the OBD2 readings and can't locate any obvious data problems I have tired recording the data, but the scanner only records for about a minute, each time, and it;s never happened when I was recording. I have some data recordings that tend to show a possible accelerator (APP) issue, but not definitive and that seems to be an unlikely cause.
I would have already replaced the OSS sensor, but on this year model Expy, it's inside the trans and will cost approx 700.00 so, that's a bit much on a "maybe" solution.
After this long story, my question is: Does anyone know if a failing OSS sensor can cause a limp mode issue only occasionally and not throw a code when it fails? Also, are there any scanners that can show the OSS readings? My thought was to put a T-pin in the PCM OSS output pin, run wires into the cabin and try and monitor the signal as I drive, but that get a little dangerous on the streets of California???
Lastly, my TP_d sensor never goes above 78%, nor does my APP above 64%. My scanner doesn't show voltage, just %. I would think that they should go to 100% if I put the pedal to the floor?? Maybe these are issues that cause the PCM to have a conflict and go to limp mode????
Any comments would be appreciated.
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