Here is the solution for Allison 3000 & 4000 Gen5 fault code P0218 transmission fluid over temperature condition.
DIAGNOSTIC RESPONSE:
Use default sump temp
For more Diesel machine repair,please refer to:
2023 Diesel DTC Solutions V2.9.98+ Diesel Explorer 2.0+Instruction
CIRCUIT DESCRIPTION:
The Transmission Fluid Temperature (TFT) sensor is incorporated into the internal wiring harness and measures the sump temperature. The TFT sensor changes its resistance value based on the temperature of the transmission fluid. This test detects high transmission fluid temperature.
ACTION TAKEN WHEN THE DTC SETS:
When DTC P0218 is active, the following conditions occur:
1 The TCM does not iluminate the CHECK TRANS light.
2 DTC is stored in TCM history.
3 The TCM freezes shift adapts (DNA).
4 TCM defaults to hot mode shift schedule. The hot mode shift schedule limits transmission to no higher than fourth range and TCC (lockup) is inhibited to increase engine speed and improve cooler flow. In addition, if the transmission is above 4th range when an over-temperature occurs, the preselect shift schedule is used for all downshifts until 4th range is reached.
CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LGHT:
Use the diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.
The DTC goes inactive and the TCM cancels the DTC active actions when the TFT sensor signals that the fluid temperature is below 121°C (250°F) for 10 seconds or more.
DIAGNOSTIC AIDS:
NOTE: DTC may occur in vehicles with history of DTC P0712. Follow the diagnostic steps in DTC P0712 before proceeding to the diagnostic steps for this DTC. Repairing the condition that sets DTC P0712 will likely eliminate DTC P0218.
Using the diagnostic tool for PC-Service Tool, monitor the transmission fluid temperature to verify that it rises in cycles and then stabilizes.
Monitor and record snapshot fluid temperature.
Follow transmission overheat troubleshooting in GENERAL TROUBLESHOOTING OF PERFORMANCE COMPLAINTS for problem: OVERHEATING INDICATED BY DTCs P0218, P273F OR FLUID CONDITION, and if equipped with a retarder follow problem RETARDER FEELS WEAK.
TFT sensor resistance is available on the diagnostic tool for PC-Service Tool Data Monitor grid. Prior to ‘Connect’ for diagnostic tool, check the ‘Troubleshoot Specific Problem’ box under the “Connection Options” and then check the ‘Sensor, Voltage, Ohms, and Counts Data’ box. Check if TFT sensor resistance is increasing, decreasing, or stationary with fluctuations in fluid temperature. Normal circuit operation is indicated if sensor resistance decreases as fluid temperature increases, and sensor resistance increases as fluid temperature decreases.
Review aplicable information in CONTROL SYSTEM AND TRANSMISSION SPECIFICATIONS to find additional circuit specifications, system and connector diagrams, and troubleshooting tips.
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