Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Crash Signalling




Crash Signalling


The Multiple Restraint System (MRS II) control module provides a switched signal to the GM in the event of an accident. The signal is an output function of the MRS control module and becomes active when MRS determines a crash has occurred.

When active, the GM unlocks the door lock actuators, switches on the interior lights and signals the LSZ via the K bus to activate the hazard warning flashers.

Once the crash signal is active, the GM will not respond to lock requests from the system until the ignition switch is cycled or a front door is opened.