2
Diagnostics, Troubleshooting and Testing
26
WABCO
Maintenance Manual MM-1306 (Revised 08-18)
Electrical System Troubleshooting
Refer to the Diagnostic Trouble Code Table for further information.
The following are the troubleshooting sections and sub-sections
referenced in the last column of the Diagnostic Trouble Code Table.
The following procedures require a multi-meter.
CAUTION
Use care to avoid damaging the connector pins when
performing electrical checks.
Harness Routing and Associated Wire Fatigue or
Abrasion
Wire fatigue will occur at any harness location where sufficient
harness motion allows bending of the wiring. When this occurs,
individual harness wires become weakened and can break. The
harness can have intermittent or permanent open circuit failures
causing the CMS to malfunction.
Harness abrasion will occur at any harness location where sufficient
harness motion allows rubbing of the harness against adjacent
vehicle components. When this occurs, the outer harness jacket and
the individual wire insulation can wear, causing short circuits
between each of the exposed wires or to the vehicle chassis causing
the CMS to malfunction. The harness is especially susceptible to
wear when the harness rubs against a sharp edge.
Both wire fatigue and harness abrasion can be prevented by
correctly attaching the harness to the chassis at closely spaced
intervals while avoiding contact with sharp edges. The harness
should be secured with tie wraps every two feet or less in areas
where damage may occur. Tie wraps should be tightened with a tie
wrap gun set to the appropriate setting to correctly secure the
harness without allowing a loose mounting but also not causing the
harness to be over-tightened. Over-tightening the tie wrap to the
harness can crush the harness jacket and conductors causing
harness damage and system failures.
Radar Connector Pinout
The radar harness is connected to the radar sensor using an
eight-pin connector. Figure 2.18.
Figure 2.18
Table C: Radar Harness Connector Pinouts
Display Connector Pinouts
The display harness is connected to the display mounted in the
dashboard.
Remove the dash to access the back of the display and harness
connector. Figure 2.19.
Figure 2.19
Figure 2.18
Pin
Circuit
1
+12V (or ignition)
2
Ignition
3
J1939 High
4
No Connection
5
No Connection
6
J1939 Low
7
No Connection
8
Ground
Figure 2.19
40118
6
1
a
1
2
3
4
5
6
7
8
40118
6
2
a
5
6
7
8
1
2
3
4
