Emergency Programs In the Event of A Fault

Introduction

The transmission electronic control system operates in combination with mechanical components, the Motronic 1.8 fuel injection/ignition system and the combined instrument. The various electronic Systems influence each other by exchanging signals.

Thus, in certain cases, an indicated transmission fault may be due to a fault in one of the other systems. Certain electrical accessories may, if incorrectly installed, also cause control system faults.

For this reason, troubleshooting is based on the assumption that both mechanical and electrical faults may be present. In the case of mechanical faults not detected by the OBD system, troubleshooting should be performed on the transmission as before. In the case of both mechanical and electrical faults detected by the OBD system, troubleshooting should be carried out with the aid of the DTCs displayed.

When a fault is recorded by the TCM, one of two auxiliary programs - an emergency program or a 'limp-home' program - will be activated to deal with the situation.

Emergency program

The control system implements certain measures to protect the transmission while maintaining maximum driving performance.

The malfunction indicator lamp (MIL) on the combined instrument will flash with certain exceptions. Diagnostic Trouble Code Descriptions

Although gearshifting will operate, the lock-up function will not.
Maximum line pressure will prevail (in the case of certain faults), giving rise to hard gearshifting.
The combination of lock-up failure and hard gearshifting indicates an electrical system fault.

'Limp-home' program

The limp-home program is an emergency program which is activated if the control system detects a serious fault. In this case, the TCM will interrupt the supply to protect the transmission.

The MIL on the combined instrument and the LEDs on the driving mode selector will flash. Automatic gearshifting will be prevented by the absence of a supply to the solenoids, the transmission operating only in 4th gear in position D and in 3rd in position L.

Manual gearshifting will be possible between 3rd and 4th, and between positions D, L, P, N and R.

Important!
The gear selector lever should be moved to position L when starting/driving to reduce the stresses on the transmission.