Allison 1000 & 2000 Gen 4 Fault Codes: P0727 Engine Speed Input Circuit No Signal CIRCUIT DESCRIPTION:The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member. Two signal wires extend from one end of the housing and an exposed end of the pole piece is at the opposite end of the housing. The permanent magnet produces lines of flux around...

Allison 1000 & 2000 Gen 4 Fault Codes: P0731 Incorrect 1st 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. First range is selected and attained.3. DTC P0716, P0717, P0721, or P0722 is not active. CONDITIONS FOR SETTING THE DTC:DTC P0731 sets when the calculated first range ratio (steady state) differs from the known first range ratio. ACTION TAKEN...

Allison 1000 & 2000 Gen 4 Fault Codes: P0732 Incorrect 2nd 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. Second range is selected and attained.3. DTC P0716, P0717, P0721, or P0722 is not active. CONDITIONS FOR SETTING THE DTC:DTC P0732 sets when the calculated second range ratio (steady state) differs from the known second range ratio. ACTION TAKEN...

Allison 1000 & 2000 Gen 4 Fault Codes: P0733 Incorrect 3rd 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. Third range is selected and attained.3. DTC P0716, P0717, P0721, or P0722 is not active. CONDITIONS FOR SETTING THE DTC:DTC P0733 sets when the calculated third range ratio (steady state) differs from the known third range ratio. ACTION TAKEN...

Allison 1000 & 2000 Gen 4 Fault Codes: P0734 Incorrect 4th 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. Fourth range is selected and attained.3. DTC P0716, P0717, P0721, or P0722 is not active. CONDITIONS FOR SETTING THE DTC:DTC P0734 sets when the calculated fourth range ratio (steady state) differs from the known fourth range ratio. ACTION TAKEN...