Diagnostic
Most controllers have a memory that retains codes
for situations that occurred within their own con-
trolled circuit. Also faults in the controller itself are
stored as a fault code. Both the IFAK cable and the
instrument cluster contain a controller that makes
these codes visible on a lap top computer, respec-
tively on the hour meter display. The explanation
of these codes is shown on the different fault code
tables for engine, transmission, hydraulic system
and Electronic Climate Control.
The CANbus connection itself can be verified by
checking continuity of the data inverse wires 900
(green) and the data wires 901 (yellow), and by
checking the 120 Ohm resistance value of the end
resistor. For schematic location and actual location
see Table 11.
Diagnostics of a faulty CANbus system requires
thorough knowledge and specific software. As con-
trollers cannot be repaired, there is no other option
than to replace a controller if it is found to be defec-
tive.
CENTRAL WARNING LIGHTS AND
INSTRUMENT PANEL
Most of the lights and instruments on the instru-
ment panel are controlled by CANbus signals
through pin 14 (CAN High) and pin 15 (CAN Low).
The few lights and instruments that are hard wired
can be recognized in Figure 8 through the indicated
pin numbers for connector CPS94.
To test functionality of the individual warning
lights, switch the ignition from OFF to ON. All
lights should light up for one second. As there are
no serviceable components, the entire instrument
panel must be replaced if found defective.
1.
WARNING LIGHTS
Figure 7. Central Warning Lights
2200 SRM 1944
Electrical Schematic and System Description
19