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If you use a separate acoustic signal emitter, the connection is simple: Connect its positive
cable to the grey-white cable (with a large cross-section) of the CR4 and its negative cable to
the black-white cable of the CR4.
If the original horn is to be used as a signal emitter, you must first clearly determine the
positive and negative of the horn. To find out, disconnect the horn from the electrical system
and measure the two horn cables with a test lamp against earth with the horn button pressed
down and the ignition switched on. It lights up when checking the positive cable.
• Insert the enclosed diode into the original positive wire of the horn. The white ring of the
diode must point towards the horn. The diode ensures that no current can flow from the CR4
towards the vehicle electrical system. Never install the diode in the grey-white line leading
from the CR4 to the horn!
• Connect the black-white cable to the negative cable of the horn
• Connect the grey-white cable with large cross-section between the diode and the horn to
the positive cable of the horn (see circuit diagram)
Brake light – adaptive brake light
Cut the positive cable of the brake light. This results in two open cable ends. Connect the
grey-yellow cable to the end of the cable that goes to the brake light. Connect the yellow
cable to the other end of the cable.
If you do not want to use the adaptive brake light function, connect the yellow cable to the
positive cable of the brake light. The grey-yellow cable of the CR4 is not connected in this case.
If you also do not want to use the start assistant, do not connect either cable and leave the
brake light intact.
Follow the instructions under “Operation”.
Starter relay – start assistant
The CR4 is positive-switching. To connect the CR4 to the starter relay, you must first determine
whether your vehicle has a positive-switching or a negative-switching starter relay (instruc-
tions in the appendix).
If the starter relay is positive-switching, connect the green cable to the cable leading from
the start button to the starter relay.
If the starter relay is negative-switching, it must be converted to positive-switching. To do
this, connect battery negative to the negative of the starter relay and replace the existing
positive cable of the starter relay with the green cable of the CR4. The start button can either
be omitted or converted to postive-switching as follows: