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MBS-1P Installation
Malfunction Lamp Diagnostic Switch
All MBS-1P units have a malfunction lamp diagnostic switch. This diagnostic
switch is located in the malfunction lamp wiring harness, behind the base rail
where the malfunction lamp is mounted. The diagnostic switch works much like
turning the auxiliary circuit ON and OFF on a newer model tractor. Pressing
the button on the diagnostic switch two times will produce the same result as
turning the auxiliary circuit ON and OFF two times to view a current fault.
There are subtle differences between using the diagnostic switch and the
auxiliary circuit. When using the diagnostic switch, for instance, the warning
lamp will not illuminate while the diagnostic switch is being pressed. Therefore,
instead of holding the button down on the last desired cycle (equivalent to
leaving the auxiliary circuit ON after the last desired cycle when using the
auxiliary circuit method), the diagnostic switch must be released after three
seconds to view the fault code. For example, to view a stored fault, perform the
following steps:
1. Power the system using the stop lamp circuit (red) and/or the auxiliary
circuit (blue), until the malfunction lamp goes OFF.
NOTE: This circuit can be powered with a suitable light tester or by
turning the ignition ON for newer model tractors.
2. Press and hold the button for one second, release it for one second, press
for one second, release for one second, then press and hold for three
seconds and release.
3. The malfunction lamp will then flash a stored fault code if one is present.
NOTE: The malfunction lamp diagnostic switch will not operate once
wheel speed is detected. Therefore, a stationary power up is required to
activate the switch.
The malfunction lamp diagnostic switch is an exclusive Wabash National
feature and has significant advantages. The technician is in close proximity to
the malfunction lamp where all information from the ECM is received. A quick
reference decal listing fault codes is located adjacent to the malfunction lamp
for convenience. Another advantage is that it’s not important which circuit is
powered or if both are powered, thereby eliminating some confusion.
