Computer Relearn.pdf

(26 KB) Pobierz

COMPUTER RELEARN PROCEDURES

Vehicles equipped with engine or transmission computers may require a relearn procedure after vehicle battery

is disconnected. Many vehicle computers memorize and store vehicle operation patterns for optimum

driveability and performance. When vehicle battery is disconnected, this memory is lost. The computer will use

default data until new data from each key start is stored. As computer memorizes vehicle operation for each

new key start, driveability is restored. Vehicle computers may memorize vehicles operation patterns for 40 of

more key starts.

Customers often complain of driveability problems during relearn stage because vehicle acts differently then

before being serviced. Depending on type and make of vehicle and how it is equipped, the following complaints

(driveability problems) may exist:

Harsh Or Poor Shift Quality

Rough Or Unstable Idle

Hesitation Or Stumble

Rich Or Lean Running

Poor Fuel Mileage

These symptoms and complaints should disappear after a number of drive cycles have been memorized. To

reduce the possibility of complaints, after any service which requires battery power to be disconnected, vehicle

should be road tested.

GENERIC COMPUTER RELEARN PROCEDURES

Some manufacturers identify a specific relearn procedure which will help establish suitable driveability during

relearn stage. These procedures are especially important if vehicle is equipped with and electronically

controlled automatic transmission or transaxle. Always complete procedure before returning vehicle to

customer. The following general procedures are to be used if driveability problems are encountered after power

loss or battery has been disconnected. These procedures may provide an aid in eliminating these problems.

Automatic Transmission

Set parking brake, start engine in "P" or "N" position. Warm-up vehicle to normal operating temperature

or until cooling fan cycles.

Allow vehicle to idle for one minute in "N" position. Select "D" and allow engine to idle for one minute.

Accelerate at normal throttle position (20-50%) until vehicle shifts into top gear.

Cruise at light to medium throttle.

Decelerate to a stop, allowing vehicle to downshift, and use brakes normally.

Process may be repeated as necessary.

Manual Transmission

Place transmission in Neutral position.

Ensure emergency brake has been set and all accessories are turned off.

Start engine and bring to normal operating temperature.

Allow vehicle to idle in Neutral for one minute.

Initial relearn is complete, and process will be completed during normal driving.