Trouble Code, Read off with Diagnostic Switch KM-640
The excitation lead of the Motronic system is short-circuited to ground in the diagnostic plug with KM-640.
By this means, the blink code readout is triggered when the ignition is switched on.
Any trouble codes present are now displayed via the engine telltale.
Diagnostic Switch, Connect.
Trouble code readout with Diagnostic Switch KM-640.
For this, the switch is turned to position "B" and attached to the diagnostic plug (ALDL plug) in the engine compartment.