CIRCUIT DESCRIPTION:This DTC sets if the TCM determines the primary shift selector calibration is invalid. ACTION TAKEN WHEN THE DTC SETS:1. The CHECK TRANS light illuminates.2. DTC is stored in the TCM history.3. Display may be in the wrong language and/or units (English/Metric) could be formatted incorrectly. CONDITIONS FOR CLEARING THE DTC: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 failure. DIAGNOSTIC AIDS:None Allison 1000 & 2000 Gen 5 Fault Code:P0980 Shift Solenoid 3 (SS3) Control Circuit – High...

CIRCUIT DESCRIPTION:The TCM can be calibrated to receive throttle information from a PWM signal. DTC P1891 sets when the TCM detects PWM throttle signal less than calibrated percent for a calibrated time. ACTION TAKEN WHEN THE DTC SETS:When the DTC P1891 is active, the following conditions occur:1. The CHECK TRANS light is not illuminated (non-OBD II strategy).2. The DTC is stored in the TCM history.3. The TCM freezes shift adapts (DNA).4. TCM uses default throttle values.5. The TCM forces Variable Modulated main off.6. TCM inhibits the Torque Converter Clutch (TCC). CONDITIONS FOR CLEARING THE DTC:Use the diagnostic tool to clear...

CIRCUIT DESCRIPTION:The TCM can be calibrated to receive throttle information from a Pulse Width Modulated (PWM) signal. DTC P1891 sets when the TCM detects PWM throttle signal greater than calibrated percent for a calibrated time. ACTION TAKEN WHEN THE DTC SETS:When the DTC P1892 is active, the following conditions occur:1. The CHECK TRANS light is not illuminated (non-OBD II strategy).2. The DTC is stored in the TCM history.3. The TCM freezes shift adapts (DNA).4. TCM uses default throttle values.5. The TCM forces Variable Modulated main off.6. TCM inhibits the Torque Converter Clutch (TCC). CONDITIONS FOR CLEARING THE DTC:Use the diagnostic...

CIRCUIT DESCRIPTION:SEM allows the TCM to request torque reduction from the engine controller. By reducing torque, shifts can be made quicker, at a more consistent output torque which reduces clutch temperature and increases clutch life. DTC P2637 sets when the TCM detects one of the following conditions for a minimum of four upshifts (consecutive or nonconsecutive) during one drive cycle:1. Engine Control Module (ECM) is not responding to SEM torque reduction signal request from the TCM.2. A non-approved J1939 device is interfering with the SEM torque reduction signal request. ACTION TAKEN WHEN THE DTC SETS:When DTC P2637 is active, the...

CIRCUIT DESCRIPTION:LRTP protects the transmission during low vehicle speed conditions. When an engine torque rating exceeds a predetermined value, LRTP limits engine torque in lower ranges to protect the transmission from damage during a converter stall condition. DTC P2641 sets when the TCM detects one of the following conditions for a minimum of four upshifts (consecutive or nonconsecutive) during one drive cycle:1. Engine Control Module (ECM) is not responding to the LRTP torque reduction signal request from the TCM.2. A non-approved J1939 device is interfering with the LRTP torque reduction signal request. ACTION TAKEN WHEN THE DTC SETS:When DTC P2641...