Dometic Waeco MagicSpeed MS880 Instructions De Montage Et De Service page 111

MagicSpeed MS880
The LED does not flash when a travel speed signal is received
(blue cable)
This is how to check whether the cruise control is receiving an incorrect en-
gine speed signal:
Check the travel speed signal using a voltmeter or an oscilloscope.
Make sure the signal is between 1.5 V and 24 V and the frequency range
is between 6 Hz and 8.5 kHz.
Check that the blue cable is not damaged and is properly connected to
the travel speed signal.
Test the travel speed signal on the electronic module of the cruise control:
– Connect the red cable of the voltmeter or oscilloscope to the blue cable
in the connecting plug of the electronic module.
– Connect the second cable of the voltmeter or oscilloscope to earth.
Make sure the signal at the electronic module matches that of the vehicle.
If the travel speed signal on the electronic module matches that of the vehi-
cle, the fault may be due to an incorrect PPM setting. If you chose to record
the travel speed or engine speed signal using the yellow cable, the cruise
control does not operate via the travel speed signal (blue cable).
To change the PPM setting, see chapter "Starting automatic mode" on
page 96
The electronic module does not change the engine speed in diagnosis
mode B
Perform all the other diagnosis mode tests again to make sure that the
problem is not caused by the electrical connections or by the control ele-
ment.
Switch the ignition off.
Quit diagnosis mode.
Leave the ignition switched off for several seconds.
Press the SET button again and hold it down.
Start the vehicle again to start diagnosis mode.
Repeat diagnosis mode B again.
Make sure the starter is not working.
EN
Troubleshooting
111