CHECK GEARBOX indicator lamp: Notes

Fig 1: Checking Gearbox Indicator Lamp

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Gearbox Indicator Lamp Wiring

Courtesy of SAAB-SCANIA OF AMERICA, INC.

If there is a fault in the automatic transmission or its control module, the TCM lights the CHECK GEARBOX warning lamp in the main instrument unit.

The lamp is supplied with current in the main instrument unit and grounded by the MIU's control module. TCM continuously sends bus information CHECK GEARBOX, unit ON/OFF.

On receiving CHECK GEARBOX, the control module grounds the output of the lamp which then lights up.

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

When the ignition is turned on, the TCM lights the lamp for approx. 3 seconds and if there is no fault the lamp will go out.