Waeco MagicSpeed MS880 Diagnose-Handbuch Seite 14

Troubleshooting
The LED on the electronic module does not light up when you apply
the brake
NOTE
I
For reasons of safety, the cruise control does not work when there
are problems with the original brake light circuit.
Therefore, check that the brake lights are working properly.
➤ Make sure the LED on the electronic module lights up when you press the
buttons on the control element.
➤ If the LED does not light up, check the power supply and earth connection
of the electronic module.
There should be a voltage of +12 V on the orange cable when the igni-
tion is switched on.
The green cable should have a good earth connection.
➤ Check the connection of the brown and brown/white cable to the brake
light switch using a voltmeter.
Test the cables with the ignition switched on, because some brake light
circuits are powered via the ignition.
The brown/white cable of the electronic module should be connected to a
brake light switch cable which is connected to either the permanent posi-
tive terminal (terminal 30) or to the ignition (terminal 15).
The brown cable should be connected to the brake light switch cable,
which connects the brake light lamp and the brake light switch. This
gives an earth signal from the brake light lamp supply cable when the
brake pedal is not applied, and a positive signal (+12 V) when the brake
pedal is applied.
The LED does not flash when an engine speed signal is received
(yellow cable)
This is how to check whether the cruise control is receiving an incorrect
engine speed signal:
➤ Check the engine speed signal using a voltmeter or an oscilloscope.
➤ Make sure the signal is between 6 V and 250 V and the frequency range
is between 6 Hz and 488 Hz.
➤ Check that the yellow cable is not damaged and is properly connected to
the engine speed signal.
14
MagicSpeed MS880
EN