airline tech
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- Joined
- Aug 24, 2022
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- Location
- Midwest - KS
- Vehicle(s)
- 2022 Ranger Lariat-Super Crew, Cactus Gray
- Occupation
- Aircraft Tech
Ok, I did some digging:
The P0600 code generated (Limp-Mode - Fail Safe)
That enables these limitations for the truck
1. Engine RPM Limited to 2,000 to 3,000 RPMs
2. Max Speed = approximately 35 MPH
3. Transmission Defaults to - 3rd Gear
So, ALL the holes in the Swiss Cheese lined up at the time of the event and you just happened to be in a - Passing Gear (Downshift) at the time.
Thus, the PCM immediately defaulted to 3rd gear as this is what it is programmed to do.
The secondary code P27B5 - is the PCM seeing a Gear Ratio (Mismatch) from that downshift and the PCM could not see what the actual gear it was in from the Primary P0600 Code.
So, it appears that the engineers designed this (Fail Safe-Limp Mode) Programming to be in a (Low Gear) situation and limiting (3rd Gear) only as its drive gear, thus not damaging the transmission.
I think they missed - a What If situation of (Higher Gears + A High Demand -Passing- Downshift) and it abruptly downshifted to a Lower Gear than it was commanding.
The most likely scenario here is the PCM lost power (lower than required) due to the charging system issue or the inability of the battery to accept the charge.
Be it a bad battery or another issue with the charging system - I would highly recommend a full system check with the new battery - just in case there is another issue that has not been addressed to potentially head off another event such as this when the new/rebuilt transmission is installed.
Just because the (Battery Light) stopped displaying does not entirely mean the system is ok.
It's better to confirm with system tests.
The P0600 code generated (Limp-Mode - Fail Safe)
That enables these limitations for the truck
1. Engine RPM Limited to 2,000 to 3,000 RPMs
2. Max Speed = approximately 35 MPH
3. Transmission Defaults to - 3rd Gear
So, ALL the holes in the Swiss Cheese lined up at the time of the event and you just happened to be in a - Passing Gear (Downshift) at the time.
Thus, the PCM immediately defaulted to 3rd gear as this is what it is programmed to do.
The secondary code P27B5 - is the PCM seeing a Gear Ratio (Mismatch) from that downshift and the PCM could not see what the actual gear it was in from the Primary P0600 Code.
So, it appears that the engineers designed this (Fail Safe-Limp Mode) Programming to be in a (Low Gear) situation and limiting (3rd Gear) only as its drive gear, thus not damaging the transmission.
I think they missed - a What If situation of (Higher Gears + A High Demand -Passing- Downshift) and it abruptly downshifted to a Lower Gear than it was commanding.
The most likely scenario here is the PCM lost power (lower than required) due to the charging system issue or the inability of the battery to accept the charge.
Be it a bad battery or another issue with the charging system - I would highly recommend a full system check with the new battery - just in case there is another issue that has not been addressed to potentially head off another event such as this when the new/rebuilt transmission is installed.
Just because the (Battery Light) stopped displaying does not entirely mean the system is ok.
It's better to confirm with system tests.
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