Rick's Free Auto Repair Advice

Adaptive memory — Retain while changing battery

Adaptive memory — What is adaptive memory

Each engine control module (ECM), powertrain control module (PCM), electronic control module (ECU)  and transmission control module (TCM) and other accessory modules are loaded with factory programming during its initial build. As you drive the vehicle and the engine and transmission wear, the modules make adjustments to the factory programming to account for the wear.

These adjustments are referred to as adaptive memory. The modifications are held in “volatile” memory chips, which means they require power to retain the data. If your battery dies or you replace your car battery and don’t provide backup power to the modules, your modules will forget the adaptive memory settings.

What settings are held in adaptive memory?

Air/fuel mixture fuel trims
Changes to transmission shift points
Throttle body “home” positions.
Power window and power seat settings
Radio presets

What happens if you don’t provide backup power when replacing a battery?

1) The vehicle may not start because the throttle body home position has been lost. This usually requires a throttle body relearn procedure. In some vehicles, the relearn procedure requires the use of a high end scan tool.

2) Even if the vehicle starts, the loss of adaptive memory means the modules will revert to factory programming and the vehicle may run poorly until it relearns all new settings. This can take as long as 10 cold start drives.

3) Auto up, auto down windows and power seat settings will have to be relearned.

How to retain adaptive memory

Purchase an OBDII memory saver cable and a jumper pack

ESA30 cable

Clore ESA30 cable. Connect to OBDII port in vehicle. Connect other end to a jumper pack. Key OFF. Then swap battery while protecting the positive cable from touching metal

jumper pack

This ES5000 jumper pack from Clore Automotive is rated at 400 cold cranking amps

Posted on by Rick Muscoplat


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