1 Several systems fitted to the vehicle require battery power to be available at all times, either to ensure their continued operation (such as the clock) or to maintain control unit memories (such as that in the engine management system’s ECU) which would be wiped if the battery were to be disconnected. Whenever the battery is to be disconnected, first note the following, to ensure that there are no unforeseen consequences of this action:

1. First, on any vehicle with central locking, it is a wise precaution to remove the key from the ignition, and to keep it with you, so that it does not get locked in if the central locking should engage accidentally when the battery is reconnected.
2. The engine management system’s ECU will lose the information stored in its memory – referred to by Ford as the ‘KAM’ (Keep-Alive Memory) – when the battery is disconnected. This includes idling and operating values, and any fault codes detected – in the case of the fault codes, if it is thought likely that the system has developed a fault for which the corresponding code has been logged, the vehicle must be taken to a Ford dealer or suitably-equipped specialist for the codes to be read, using the special diagnostic equipment necessary for this (see Chapter 4A). Whenever the battery is disconnected, the information relating to idle speed control and other operating values will have to be reprogrammed into the unit’s memory. The ECU does this by itself, but until then, there may be surging, hesitation, erratic idle and a generally inferior level of performance. To allow the ECU to relearn these values, start the engine and run it as close to idle speed as possible until it reaches its normal operating temperature, then run it for approximately two minutes at 1200 rpm. Next, drive the vehicle as far as necessary – approximately 5 miles of varied driving conditions is usually sufficient – to complete the relearning process.
3. If the battery is disconnected while the alarm system is armed or activated, the alarm will remain in the same state when the battery is reconnected. The same applies to the engine immobiliser system (where fitted).
4. If a trip computer is in use, any information stored in memory will be lost.
5. If a Ford Keycode audio unit is fitted, and the unit and/or the battery is disconnected, the unit will not function again on reconnection until the correct security code is entered. Details of this procedure, which varies according to the unit and model year, are given in the Ford Audio Systems Operating Guide supplied with the vehicle when new, with the code itself being given in a Radio Passport and/or a Keycode Label at the same time. Ensure you have the correct code before you disconnect the battery. For obvious security reasons, the procedure is not given in this manual. If you do not have the code or details of the correct procedure, but can supply proof of ownership and a legitimate reason for wanting this information, the vehicle’s selling dealer may be able to help.
6. After reconnecting the battery, it will be necessary to re-initialise each electric window motor separately. Press the ‘close button’ until the window is fully closed, and keep the button pressed for a further second. Release the ‘close’ button, then press it two or three times for a second each time. Press the ‘open’ button and hold it for one second after the window is fully open. Briefly press the ‘close’ button to the second action point - if the procedure has been successful, the window will close automatically. If the window does not close automatically, repeat the procedure. Carry out the procedure on the remaining electric windows.
7. On diesel models, after reconnecting the battery, turn the ignition switch to position II for 30 seconds to carry out the engine management initialisation procedure. Do not press the accelerator pedal or attempt to start the engine during this 30-second period, or the initialisation procedure will fail.

2 Devices known as ‘memory-savers’ (or ‘code-savers’) can be used to avoid some of the above problems. Precise details vary according to the device used. Typically, it is plugged into the cigarette lighter, and is connected by its own wires to a spare battery; the vehicle’s own battery is then disconnected from the electrical system, leaving the ‘memory-saver’ to pass sufficient current to maintain audio unit security codes and ECU memory values, and also to run permanently-live circuits such as the clock, all the while isolating the battery in the event of a short-circuit occurring while work is carried out.