Troubleshooting
February 2012 7-4 P/N 06-237058-001
PMU GROUND FAULT +VDC On Low impedance path between positive
field conductor and earth ground.
Normal earth-ground offset voltage is
6.6 (nom.) Vdc relative to system
common (e.g.. PMU J9 (-) terminal, refer
to Figure 2-9)
• Use the control unit menu to view the
ground fault offset voltage.
• Use the control unit menu to execute the
Find Ground Fault option.
• Continuously monitor DC voltage between
earth-ground stud on left side of back box
and PMU J9 (-) terminal. Voltage should
be 6.6 (nom.) Vdc. Earth ground is
positive relative to system common.
• If the menu operation does not find the
origin of the ground fault, remove field
circuits one at a time until earth-ground
offset voltage restores to 6.6 (nom.) Vdc.
• Check for connections to earth ground on
field circuit whose removal restored
proper earth-ground offset voltage.
• If applicable, disconnect USB port-to-PC
connection and check for ground fault.
PMU# 24VDC OUTPUT HIGH On
PMU# 24VDC OUTPUT LOW On
The combined power-supply output to
the control unit is too high or low.
• Measure the PSU output voltage at
terminals 4 & 5 (refer to Figure 2-8).
• Remove secondary and primary power.
Label and disconnect all field wiring.
CAUTION
: Disconnect all electrical
control heads and short together and
tape wiring to actuators (if applicable).
• Inspect connections of power-supply-
connector flying leads to power supply
unit. Tighten if necessary.
• Ensure AC Selector Switch on power
supply unit is correctly set for line voltage.
Refer to Figure 2-4.
• Re-install printed-circuit board, connect
field wiring, and apply primary and
secondary power if loose connection(s).
Perform functional tests as necessary
• Replace power supply unit if no loose
connections or AC Selector-Switch
problem.
PMU# PSU1 24VDC OUTPUT
HIGH On
PMU# PSU1 24VDC OUTPUT
LOW On
PMU# PSU2 24VDC OUTPUT
HIGH On
PMU# PSU2 24VDC OUTPUT
LOW On
The PSU1 and/or PSU2 output to the
system is too low or too high.
• Check connections from the PMU to the
PSU(s).
• Measure the PSU output voltages at
terminals 4 & 5 of both power supplies
(refer to Figure 2-8).
Table 7-1. General System Events (Continued)
General System Events
Error Message Probable Cause Corrective Action
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