Self-destruct mechanism

The self-destruct mechanisms were a component of the Dalek casing which allowed Daleks to self-destruct, essentially committing suicide. (PROSE: Prisoner of the Daleks)

During the Second Dalek War, the Tenth Doctor claimed that a casing contained enough self-destruct mechanisms to "keep a team of bomb-disposal experts happy for a month." This made the casing a dangerous hazard to others seeking to open it, even in the event that the Dalek mutant within had since perished. (PROSE: Prisoner of the Daleks)

At the end of the Shoreditch Incident, the Supreme Dalek self-destructed when the Seventh Doctor revealed that Skaro was destroyed. (TV: Remembrance of the Daleks)

The "Metaltron", who believed it was the last of its kind following the Last Great Time War, asked Rose Tyler to order it to self-destruct after it gained human emotions from her. Preferring death to a life with emotions, this Dalek ejected all the sense globes from its base unit to form a force field in which it was completely destroyed. (TV: Dalek)

In the 22nd century, a group of Daleks on Earth initiated self-destruction after the Tenth Doctor used a proton cannon to make them intangible. (COMIC: Extermination of the Daleks)

When the Eleventh Doctor found himself in the Dalek Asylum, a damaged Dalek, deprived of its gunstick, attempted to use its self-destruct to kill him. Before it casing detonated, the Doctor managed to hack into its locomotion systems, sending the Dalek hurtling towards others of its kind, the resulting explosion destroying it and them. Despite bearing the casing utilized in the Last Great Time War, this Dalek's self-destruct lacked the forcefield and manifested itself merely as a large explosion, possibly due to its damaged state. (TV: Asylum of the Daleks)