Technical Description: Limp-home

Fig 1: Identifying Limp-Home (1 Of 2)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Identifying Limp-Home (2 Of 2)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Should a somewhat more serious system fault develop, such as mechanical failure in the system's output functions or an internal control module fault, all control module functions will be disconnected at the same time as the control module sends the "CHECK GEARBOX ON" message on the bus. This indicator lamp will then light up in the main instrument unit. A diagnostic trouble code will also be generated.

In this situation the transmission will be controlled only by the hydraulic control system. This limits the transmission's functions and the car can only be driven to a garage for repairs. That is why it is called Limp-Home.

Limp-home mode selects the following gear positions:

Note that 2nd gear must be selected manually in position L.

The CHECK GEARBOX lamp lights up and a diagnostic trouble code is stored in the memory.

Fig 3: Connection Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.