CHECK GEARBOX warning lamp

Fig 1: Identifying Gearbox Warning Lamp Communication Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

When the transmission or TCM malfunctions, the CHECK GEARBOX warning lamp in the main instrument unit comes on.

The lamp is supplied with current in the main instrument unit and grounded by the MIU's control module.

If a fault occurs in the transmission, TCM will send bus information "CHECK GEARBOX ON".

The main instrument unit's control module grounds the output for the CHECK GEARBOX warning lamp, which then lights up.

The lamp goes out when the TCM sends the message "CHECK GEARBOX OFF".

When the engine is started, the TCM lamp comes on for 3 seconds. If there are no faults in the system the light will extinguish.

Fig 2: Connection Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.