INTRODUCTION
Note. Before replacing any component that scan tool suggests are faulty. Ensure that all wiring connections and harness connectors are okay. Ensure that power and ground circuits are functioning properly. For circuit identification, see appropriate WIRING DIAGRAM under ENGINE PERFORMACE in SYSTEM WIRING DIAGRAMS for vehicle being tested.
BODY CONTROLS
Vehicles equipped with body, air conditioning, anti-lock brake or memory computers may require a computer relearn procedure after components are replaced or the vehicle battery is disconnected. Vehicle computers memorize and store vehicle information and operation selections. When the vehicle battery is disconnected, vehicle computer memory may be lost, requiring relearning or resetting. Depending on the vehicle and how it is equipped, the following memories may exist
- Seat position.
- Tilt/telescoping steering wheel position.
- Mirror position.
- Radio presets and anti-theft code.
- Clock.
- Remote keyless entry custom features.
- Door key lock entry custom features.
- Power window or sunroof operation.
These do not affect vehicle operation. For systems that do not affect operation, see appropriate article for relearn procedures. Other computer relearn procedures are required for vehicle or system operation. These may include
- Initial control unit programming.
- Traction control yaw sensor initializing.
- Multiplex communication.
- Anti-theft system or engine immobilizer system passwords.
ENGINE CONTROLS
Vehicles equipped with powertrain control computers may require a computer relearn procedure after the vehicle battery is disconnected. Vehicle computers memorize and store vehicle operation patterns for optimum driveability and performance. When the vehicle battery is disconnected, this memory is lost, which may result in a driveability problem. Depending on the vehicle and how it is equipped, the following driveability problems may exist
- Rough or unstable idle.
- Hesitation or stumble.
- Rich or lean running.
- Poor fuel mileage.
- Harsh or poor transmission/transaxle shift quality.
Default data is used until NEW data from each key start is stored. As the computer restores its memory from each new key start, driveability is restored.
Driveability problems may occur during the computer relearn stage. To accelerate computer relearn process after battery removal and installation, specified computer relearn procedures should be performed. See appropriate procedures for specified manufacturer.
LAND ROVER
To enable shorter cranking times, when ignition is turned off, ECM memorizes crankshaft and camshaft positions. If battery or ECM is disconnected, memory is lost. Drive vehicle to enable ECM to relearn driveability. Inform your customer that they may experience driveability different from what they are accustomed to until ECM completes relearn function.
IMMOBILIZER
If ECM is replaced ECM must learn identification code for immobilizer ECU and remote handsets. A Land Rover TestBook must be used to reconfigure the immobilization system.
POWER WINDOW CALIBRATION
If battery is disconnected, power windows will require calibration to establish upper and lower stop points. Immediately after Central Control Unit (CCU) or battery is connected, CCU will energize down contacts on all window switches. To ensure calibration is successful; ensure that alarm is disarmed and vehicle is unlocked, that all doors and tailgate are in closed position, that sunroof is open to full hardback or softback position. DO NOT open any door until calibration procedure is completed. Turn ignition on, using appropriate window switch raise each window until motor stalls and window is fully closed. Turn ignition off. If calibration is not successful CCU will sound a warning for about .8 seconds and windows will fully lower. If calibration fails, repeat procedure.