Allison 1000 & 2000 Gen 4 Fault Codes: P0847 Transmission Pressure Switch Solenoid D Circuit Stuck Closed CIRCUIT DESCRIPTION:The Pressure Switch Manifold (PSM) is a multiple-switch assembly made up of three normally open (N/O) and one normally closed (N/C) pressure switches. The D pressure switch monitors D shift valve positioning and relays it to the TCM. When D pressure switch is in the open state, D shift valve should be in the destroked position. CONDITIONS FOR RUNNING THE DTC:1. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V...

Allison 1000 & 2000 Gen 4 Fault Codes: P0848 Transmission Pressure Switch Solenoid D Circuit High CIRCUIT DESCRIPTION:The Pressure Switch Manifold (PSM) is a multiple-switch assembly made up of three normally open (N/O) and one normally closed (N/C) pressure switches. The D pressure switch monitors D shift valve positioning and relays it to the TCM. When D pressure switch is in the open state, D shift valve should be in the destroked position. CONDITIONS FOR RUNNING THE DTC:1. Components are powered and the ignition voltage is greater than 5V.2. DTC P0561, P0562, or P0563 is not active.3. D shift valve...

Allison 1000 & 2000 Gen 4 Fault Codes: P0870 Transmission Pressure Switch Solenoid E Circuit CIRCUIT DESCRIPTION:The Pressure Switch Manifold (PSM) is a multiple-switch assembly made up of three normally open (N/O) and one normally closed (N/C) pressure switches. The E pressure switch monitors E shift valve positioning and relays it to the TCM. When E pressure switch is in the open state, E shift valve should be in the destroked position. CONDITIONS FOR RUNNING THE DTC:1. Components are powered and the ignition voltage is greater than 5V.2. DTC P0561, P0562, or P0563 is not active.3. E shift valve is...

Allison 1000 & 2000 Gen 4 Fault Codes: P0871 Transmission Pressure Switch Solenoid E Circuit Stuck Open CIRCUIT DESCRIPTION:The Pressure Switch Manifold (PSM) is a multiple-switch assembly made up of three normally open (N/O) and one normally closed (N/C) pressure switches. The E pressure switch monitors E shift valve positioning and relays it to the TCM. When E pressure switch is in the open state, E shift valve should be in the destroked position. CONDITIONS FOR RUNNING THE DTC:1. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V...

Allison 1000 & 2000 Gen 4 Fault Codes: P0872 Transmission Pressure Switch Solenoid E Circuit Stuck Closed CIRCUIT DESCRIPTION:The Pressure Switch Manifold (PSM) is a multiple-switch assembly made up of three normally open (N/O) and one normally closed (N/C) pressure switches. The E pressure switch monitors E shift valve positioning and relays it to the TCM. When E pressure switch is in the open state, E shift valve should be in the destroked position. CONDITIONS FOR RUNNING THE DTC:1. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V...