Allison

Allison 1000 & 2000 Gen 4 Fault Codes: P0735 Incorrect 5th Gear Ratio CIRCUIT DESCRIPTION:The Transmission Control Module (TCM) uses input from the turbine speed sensor and output speed sensor to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current range. CONDITIONS FOR RUNNING THE DTC:1. Output speed exceeds 200 rpm.2. Fifth range is selected and attained.3. DTC P0716, P0717, P0721, or P0722 is not active. CONDITIONS FOR SETTING THE DTC:DTC P0735 sets when the calculated fifth range ratio (steady state) differs from the known fifth range ratio. ACTION TAKEN...

Allison 1000 & 2000 Gen 4 Fault Codes: P0736 Incorrect Reverse Ratio CIRCUIT DESCRIPTION:The Transmission Control Module (TCM) uses input from the turbine speed sensor and output speed sensor to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current gear. CONDITIONS FOR RUNNING THE DTC:1. Output speed exceeds 200 rpm.2. Reverse is selected and attained.3. DTC P0716, P0717, P0721, or P0722 is not active. CONDITIONS FOR SETTING THE DTC:DTC P0736 sets when the calculated reverse range ratio (steady state) differs from the known reverse range ratio. ACTION TAKEN WHEN THE...

Allison 1000 & 2000 Gen 4 Fault Codes: P0741 Torque Converter Clutch System Stuck Off CIRCUIT DESCRIPTION:The Transmission Control Module (TCM) uses data from the engine speed sensor and the turbine speed sensor to calculate torque converter slip value. The TCM then compares this calculated slip value to a preset value in the TCM calibration. CONDITIONS FOR RUNNING THE DTC:1. DTC P0122, P0123, P0716, P0717, P0721, P0722, or P0743 (previously P1860) is not active.2. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V...

Allison 1000 & 2000 Gen 4 Fault Codes: P0742 Torque Converter Clutch System Stuck On CIRCUIT DESCRIPTION:The Transmission Control Module (TCM) uses data from the engine speed sensor and the turbine speed sensor to calculate the torque converter slip value. The TCM then compares this calculated slip value to a preset value in the TCM calibration. CONDITIONS FOR RUNNING THE DTC:1. DTC P0122, P0123, P0716, P0717, P0721, P0722, P0726, P0727, or P0743 (previously P1860) is not active.2. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less...

Allison 1000 & 2000 Gen 4 Fault Codes: P0743 Torque Converter Clutch PWM Solenoid Circuit – Electrical CIRCUIT DESCRIPTION:The torque converter clutch (TCC) solenoid, solenoid F, is a pulse width modulated solenoid. Pulse width modulation (PWM) occurs when the signal from the transmission control module (TCM) to a solenoid is modulated at an established frequency, causing the steel check ball in the solenoid to rapidly open and close the solenoid passage. This serves to vary the output fluid pressure. CONDITIONS FOR RUNNING THE DTC:1. DTC P0122, P0123, P0716, P0717, P0721, P0722, or P0743 (previously P1860) is not active.2. The components...