Emergency programs

An emergency program is activated to deal with the fault when the transmission control module (TCM) detects a transmission fault (permanent fault). The control system takes corrective action to protect the transmission and maintain as much driveability as possible. Minor malfunctions do not activate an emergency program. There are different programs depending on the type of malfunction detected.

Emergency mode I

Emergency mode II

Emergency mode III

Limp-home mode

Emergency mode I is activated in the event of minor faults and the Limp-home mode is activated for the most serious faults. If the malfunction is intermittent, the transmission control module (TCM) returns to normal operation the next time the ignition is switched on.

Emergency mode I 

• The combined instrument panel warning lamp flashes for certain diagnostic trouble codes (DTCs).
• The transmission shifts in all gears but transmits no signal to the lock-up solenoid. This means that lock-up is not available.
• There is no adaptation of the gear slippage times at high altitude (High Altitude Compensation) which can result in poor gear shifting quality.

Emergency mode II 

• As for Emergency mode I
• No reduction of line pressure when moving the gear selector between positions P-R, N-R and N-D. This results in harsh shifting.
• No torque limiting request to engine control module (ECM) when shifting.
• The warning lamp in the combined instrument panel flashes.

Emergency mode III 

• Remedy as for Emergency modes I and II.
• No control of line pressure solenoid STH. Constant maximum system pressure. This results in harsh shifting and harsher gear engagement in positions P-R, N-R and N-D.

Limp-home mode 

• The transmission control module (TCM) stops activating solenoids, which results in the transmission not shifting at all. The transmission operates only in 3rd gear in positions 3 and L, 4th gear in position D and reverse in position R. Shifting can only be carried out manually between 3rd and 4th gear (D position) and reverse gear.
• No control of line pressure solenoid STH. Constant maximum system pressure. This results in harsh shifting and harsher gear engagement in positions P-R, N-R and N-D.
• The warning lamp in the combined instrument panel flashes.