Limp Home Function

If the ECM detects the fault of the SMARTRA or transponder, the ECM will allow limp home function of the immobilizer. Limp home is only possible if the user password (4 digits) has been given to the ECM before. This password can be selected by the vehicle owner and is programmed at the service station. The user password can be sent to the ECM via the special tester menu.

Only if the ECM is in status "learnt" and the user password status is "learnt" and the user password is correct, the ECM will be unlocked for a period of time (30 sec). The engine can only be started during this time. After the time has elapsed, engine start is not possible.

If the wrong user password is sent, the ECM will reject the request of limp home for one hour. Disconnecting the battery or any other action cannot reduce this time.

After connecting the battery to the ECM, the timer starts again for one hour.

Fig 1: Scan Tool Display - Limp Home Function (1 Of 2)

Courtesy of KIA MOTORS AMERICA, INC.

Fig 2: Scan Tool Display - Limp Home Function (2 Of 2)

Courtesy of KIA MOTORS AMERICA, INC.

The limp home can be activated also by the ignition key. The user password can be input to the ECM by a special sequence of ignition on/off.

Only if the ECM is in status "learnt" and the user password status is "learnt" and the user password is correct, the ECM will be unlocked for a period of time (30 sec). The engine can be started during this time. After the time has elapsed, engine start is not possible. After a new password has been input, the timer (30 sec.) will start again.

After ignition off, the ECM is locked if the timer has elapsed 8 seconds. For the next start, the input of the user password is requested again.

Fig 3: Identifying PCM /ECM Blinking Pattern

Courtesy of KIA MOTORS AMERICA, INC.