Troubleshooting The Analog Command Signal - Meritor TACTX HMIS Maintenance Manual

Section 5
If present, verify that the master disconnect is
turned to the ON position. Turn the ignition switch
to the ON position. Locate the sensor with a
reported fault and disconnect the 3-pin Delphi Con-
nector. Use a multimeter to measure the voltage
between pin-A and pin-C of the harness connector
(Figure 6.26). This should read between 4.5 and
5.5 volts.
If correct voltage is not present, check the supply
voltage at one of the other sensor locations. If volt-
age is not present at either location, verify that the
PCU has the correct supply voltage and is commu-
nicating over the J1939 link. If the PCU is opera-
tional, check the following.
• Examine splices at the sensor supply and
return connection points in the harness.
• Verify that none of the other components on
the sensor supply is shorted. (The sensor is
short-circuit protected, so removing the short
should restore correct operation.)
• An adapter cable may be used to check the
sensor supply voltage at the PCU while it is
powered.
If the PCU sensor supply is defective, replace the
PCU. Refer to the procedure in Section 6.
If 5V is not present between pin-A and pin-C of the
harness and the sensor but is present at other
locations, it will be necessary to trace the cabling
between the PCU and the sensor. If the sensor
fault reads "out of range-high," the return (ground)
signal is probably open. If the sensor fault reads
"out of range-low," the supply lead may be open.
If correct sensor supply voltage is present, but the
sensor is inoperative, replace the sensor using the
procedure in Section 6.
Troubleshooting the Analog Command
Signal
If the suspension control system uses an analog
command signal, and the PCU logs and transmits
a fault related to this input, proceed as follows.
Locate the sensor (typically in the dash panel
area). Disconnect it from the harness. Check for a
valid supply voltage using the same technique as
for troubleshooting the height control sensors.
Meritor Maintenance Manual MM-0997 (Revised 12-09)
R6
2.2k, 1/2W
R5
2.2k, 1/2W
Deutsch 4-pin Socket
R4
4 2.2k, 1/2W
3
2
1
R3
J1
2.2k, 1/2W
R2
2.2k, 1/2W
R1
2.2k, 1/2W
Figure 5.7 Analog Command Signal — Typical
Implementation (May Vary Between Applications)
If the device is receiving correct supply voltage,
use a multimeter to check the overall resistance of
the device. (This should be in the range of 1k to
20k for most applications.)
Then check the resistance at the center tap. The
resistance should vary from a minimum level to a
maximum level within the maximum range of the
device as the mode selector is moved.
If the device is not operating, it must be repaired or
replaced.
Troubleshooting
SW 1
SW ROTARY 1P-5W
4007559a
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