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Computer Relearn Procedures Chevrolet Cab & Chassis K3500

Computer Relearn ~514 words

INTRODUCTION

Vehicles equipped with engine or transmission computers may require a 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. 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 relearn stage. Depending on the vehicle and how it is equipped, the following driveability problems may exist

  1. Rough or unstable idle.
  2. Hesitation or stumble.
  3. Rich or lean running.
  4. Poor fuel mileage.
  5. Harsh or poor transmission shift quality.

To accelerate relearn process after battery removal and installation, vehicle should be road tested in the following manner

  1. Vehicle at normal operating temperature (cooling fan cycles).
  2. Accelerate at normal throttle position (20-50%).
  3. Cruise at light to medium throttle.
  4. Decelerate to a stop, downshifting and using brakes normally.

Manufacturers identify specific relearn procedures. See RELEARN PROCEDURES. Always complete the procedure before returning the vehicle to the customer.

VEHICLE DRIVEABILITY RELEARN PROCEDURE

General Motors does not provide a specific procedure for driveability relearn. If a vehicle battery was disconnected for facilitating repairs or a Powertrain Control Module (PCM) was replaced, driving the vehicle will enable the PCM to relearn driveability. Inform your customer that he/she may experience driveability different from what they are accustomed to until the PCM completes it's relearn function.

TP SENSOR LEARN (CORVETTE)

If a NEW TP sensor or throttle body is installed, EBTCM must learn new TP sensor idle position voltage. This procedure is necessary to ensure effective engine torque reduction during ASR operations. TP sensor learn procedure requires a Tech-1 scan tester or T-100 (CAMS) unit.

  1. Turn ignition off. Connect Tech-1 scan tester with a Mass Storage cartridge. Turn ignition on. Select ABS/ASR feature from menu.
  2. Select F5 (TP SENSR LEARN). Press up arrow to begin learn procedure. Wait for Tech-1 scan tester to indicate COMPLETE. Turn ignition off. Disconnect Tech-1 scan tester.

Note. Ensure accelerator and brake pedals are free from any obstructions while performing TP sensor/idle learn procedure. PCM will not perform learn function with accelerator pedal or brake pedal obstructions.

Note. TP sensor/idle learn procedure should be performed with A/C on and with A/C off due to engine load differences.

TP SENSOR/IDLE LEARN (DeVILLE 4.9L)

  1. Ensure outside air temperature is greater than 50°F (10°C) to allow operation of A/C compressor. Start engine and allow to idle for 13 minutes. With engine running, enter diagnostics. See G - TESTS W/ CODES - 4.9L article in the ENGINE PERFORMANCE section.
  2. Turn ignition off. Wait 20 seconds, then turn ignition on, with engine off. Reenter diagnostics. Repeat step 2).
  3. Turn ignition off. Wait 20 seconds, then start engine. Apply brakes and place transmission in Drive. Turn Climate Control Panel (CCP) to OFF position and allow engine to idle for one minute.
  4. Turn CCP to AUTO position and ensure A/C compressor engages. Allow engine to idle for one minute. Place transmission in Park and turn ignition off.