Allison 1000 & 2000 Gen 4 Fault Codes: P0717 Turbine Speed Sensor 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: P0719 Brake Switch ABS Input Low CIRCUIT DESCRIPTION:If the vehicle is equipped with anti-lock brake system (ABS), an interface between the ABS and TCM is required. This interface allows disengagement of the Torque Converter Clutch (TCC) when the ABS is activated. This ABS action is initiated with a discrete input from the ABS system, when the ABS is activated a ground signal is sent to TCM input wire 113. This may be a ground signal direct from the ABS controller or a positive signal from the ABS controller that powers a relay...

Allison 1000 & 2000 Gen 4 Fault Codes: P0721 Output Speed Sensor Circuit Performance 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 the...

Allison 1000 & 2000 Gen 4 Fault Codes: P0722 Output Speed Sensor 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: P0726 Engine Speed Input Circuit Performance 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 the...