Limp Home Function

If the PCM (ECM) detects the fault of the SMARTRA or transponder, the PCM (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 PCM (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 PCM (ECM) via the special tester menu.

Only if the PCM (ECM) is in status "learnt" and the user password status is "learnt" and the user password is correct, the PCM (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 PCM (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 PCM (ECM), the timer starts again for one hour.

Fig 1: Scan Tool Display - COMPLETED

Courtesy of KIA MOTORS AMERICA, INC.

Fig 2: Scan Tool Display - CURRENT DATA

Courtesy of KIA MOTORS AMERICA, INC.

Fig 3: Scan Tool Display - NO. OF LEARNT KEY

Courtesy of KIA MOTORS AMERICA, INC.

Fig 4: Scan Tool Display - CODE 234567

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 PCM (ECM) by a special sequence of ignition on/off. Only if the PCM (ECM) is in status "learnt" and the user password status is "learnt" and the user password is correct, the PCM (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 PCM (ECM) is locked if the timer has elapsed 8 seconds. For the next start, the input of the user password is requested again.

Fig 5: Timing Chart

Courtesy of KIA MOTORS AMERICA, INC.