Vehicle Computer Reset / Relearn Procedures Tip

Computer Reset / Relearn Procedures

Driveability Problems After a Low or Disconnected Battery

Technology and the advancements of today’s modern vehicles are being made at an astounding rate.  Vehicle wiring that was once a simple system of wires routed from Point-A to Point-B, has become a complex network of processors and electronics control units (ECU’s).  In certain vehicles, the Electronics Control and Management Systems will “learn” and compensate for a particular driving style, weather, or traction condition.  The result is a “smart” car that will make adjustments to the engine and/or drivetrain for optimum performance all the time.

The down sides of the moderness mentioned above are the high cost of service to the vehicle and the difficulty of finding the root or source of the problem without special equipment.

Some vehicles may experience driveability problems due to a loss of memory after disconnecting the battery or if there is a power loss.  Alarm, Remote Start, and Stereo Installers should be aware that there are some basic procedures that can help alleviate a service problem.  Vehicles with engine or transmission computers may need to relearn driving information [data] as a solution to the problem.  In some cases the computer will resort back to default data, which may or may not be suitable or it may take up to 40 key starts for the system to have enough data to provide optimum driving performance.

Common Customer Complaints (Driveability Problems):

· Rough Idle

· Poor or Harsh Shift quality · Hesitation on Acceleration · Lean or Rich running · Power Loss · Lower Fuel Economy

The above symptoms should disappear once the computer has in fact fully rebooted and relearned the vehicle after a number of key starts or driving cycles.  To reduce to the possibility of customer complaints, the vehicle should at least be started and road tested.  If road testing is not allowed or forbidden, then perform the steps up to the Road Test Portion.

Here are some basic relearn procedures for Automatic and Manual Transmission vehicles unless you have specific service instructions for your particular vehicle:

AUTOMATIC TRANSMISSION:

1. Set Parking brake. 2. Start Engine in “P” or “N” position. 3. Let vehicle warm to operating temperature or wait until cooling fan cycles. 4. Press Brake pedal and Select “D”. 5. Let vehicle idle in “D” for at least one minute. 6. Begin Road Test  (May not be allowed). 7. Accelerate at normal throttle position (20-50%) until vehicle is in top gear. 8. Cruise at light/medium throttle for at least one minute. 9. Decelerate to a stop while allowing vehicle to downshift normally; use brakes normally. 10. Repeat process if needed.

MANUAL TRANSMISSION:

1. Place Transmission in Neutral. 2. Set Emergency Brake and turn off all accessories. 3. Start vehicle and bring to operating temperature or wait until cooling fan cycles. 4. Allow vehicle to idle for at least one minute. 5. Turn off engine.