SPN 3359 FMI 31 - Transmission Filter Maintenance Required (P088B)
DTC P088B
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| Figure 1.1 - SPN3359 FMI31 (Murphy Display) |
NO SCHEMATIC FOR THIS DTC
#Circuit Description
The Filter Life Monitor (FM) feature alerts the driver when a filter change is needed by illuminating the SERVICE TRANS indicator (wrench icon in keypad or lever shift selector display). FM also activates any OEM-provided SERVICE TRANS indicator or datalink message center display (refer to Figure 1.1 above). If the filter is detected as restricted, the wrench icon in the selector flashes ON and OFF for approximately 2 minutes the first time D (Drive) is selected after each Engine start. Also, DTC P088A becomes active concurrently with these other visible filter maintenance alerts. This DTC monitors the electrical state of the PS2 Filter Life Indicator (FLI) pressure switch. If PS2 is detected as open (pressurized) while the Transmission is in a forward range and with the Torque Converter Clutch/TCC (lockup) solenoid energized, the DTC becomes active. If several alerts are sent, but the PS2 switch is still detected as pressurized, DTC P088B becomes active.
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| Figure 1.2 - Shift Selector (wrench icon) |
The difference between main pressure (before the filter) and TCC lockup pressure determines whether to stroke or de-stroke the FLI pressure switch valve in the prognostic valve body within the control valve module. An active DTC and SERVICE TRANS indicator occurs at next Engine start when the operator selects D (Drive).
#Action Taken When the DTC Sets
→DTC P088B is stored in the TCM history for a number of ignition cycles.
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| Figure 1.3 - Trouble Code (P088B) |
→The wrench icon (refer to Figure 1.2 above) in the display of an Allison shift selector will flash ON and OFF for approximately 2 minutes the first time D (Drive) is selected after each Engine start.
→The TCM illuminates the CHECK TRANS light.
#Conditions for Clearing the DTC
→The feature is designed to reset itself automatically after the main filter has been changed.
→Allison DOC can clear the DTC from TCM history.
→The operator may clear the code and flashing SERVICE TRANS indicator by pressing MODE button for 10 seconds, or→FM may also be reset by selecting N-R-N-R-N-D-N on the shift selector, pausing briefly (less than 3 seconds) between each selector movement when the ignition is on and Engine not running.
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| Figure 1.4 - Shift Selector (Normal) |
→FM may be reset with a SAE J1939 message.
→Use Allison DOC 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.
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| Figure 1.5 - Clear Diagnostic Information |
#DTC P088B can caused by:
→Restricted Main Filter
→Low lockup pressure
→Open or high resistance in W118 or W158 in chassis harness.
→Open or high resistance from terminal 17 to PS2, or from PS2 to terminal 19, in control module wire harness.
→Issue with PS2
→Issue with TCM
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