Ignition Timing: Description and Operation

Ignition Retardation During Gear Selection, Checking

The Engine Control Module (ECM) receives the gear change signal via the transmission control module. The ECM then retards the ignition briefly depending on road and engine speeds. This reduces the torque and the consequent jolt of the gear change.

The VAG 1551 does not always recognize and display the signal for torque reduction because it is sent for an extremely short period.