Limp Home Tool

If the BCM detects a fault of antenna or transponder, the BCM will allow limp home function of immobilizer.

Limp home mode is only possible if the user password (4 digits) has been learnt to the BCM before.

This password can be defined by end user and is programmed at the service station.

The BCM informs the driver about the limp home condition by driven the status indicator. Then the user password can be sent to the BCM by special tool menu.

The diagnostic messages are described in "Diagnostic tool display".

Only if the BCM is in status " learnt" and the user password status is " learnt" and the " User password" is the correct one, the BCM is " released" and send " unlock" request to ECM for the time (typical 30 seconds). The engine can only be started during this time. After elapsing of timer no engine start is possible.

The number of starts by tester is limited to 255.

If wrong user passwords have been sent to BCM three times, the BCM will reject the request of limp home for one hour. Disconnecting the battery or other manipulation cannot reduce this time. After the connecting of battery to ECM the timer starts again for one hour. When a valid TP is authenticated before counter value reaches to limit, the ten counter is reset, but the timer counter (1 hour) is not affected.