Diagnostic
Interconnection between the controllers is schemat-
ically shown in Figure 6. The controllers are con-
nected through data inverse wire number 900
(green) and data wire number 901 (yellow) that are
twisted together. The purpose of twisting is to re-
duce sensitivity to electromagnetic interference.
For the same purpose there are termination resis-
tors at the extreme ends of the string of controllers.
The system will not function if both 120 Ohm resis-
tors are faulty or disconnected.
The ZF transmission controller has an end resistor
included in the controller unit.
The sensors that relate to the different controllers
are primarily shown on sheet 9 of the electrical
schematic. Sensors for the transmission are shown
on sheet 4.
The optional electronic climate control has an inde-
pendent control system that does not communicate
through can bus wires 900 and 901.
Figure 6. CAN Bus Circuit
Troubleshooting
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 fault codes. 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 can bus 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 ter-
mination resistor. For schematic and actual loca-
tion see Table 11.
Diagnostics of a faulty CAN bus systems 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.
Instrument Panel
The lights and instruments that are shaded in Fig-
ure 7 and Figure 8 are controlled by CAN bus sig-
nals. The legend also shows the related pin num-
bers of 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 defec-
tive.
1. CENTRAL WARNING LIGHT
Figure 7. Instrument Panel
Electrical Schematic and System Description
2200 SRM 1592
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