New Holland WorkMaster 50 Service Manual page 1023

DTC 78D-04-Throttle valve actuator control circuit supply voltage
too low
Control Module : ECU
Context:
The Engine Control Unit (ECU) A-9000 internally monitors the operation of the H-bridge Pulse Width Modulated (PWM)
control circuit for the Throttle Valve Actuator (TVA) Z-9001 motor actuator for electrical defects. If the ECU A-9000
senses too low an output driver supply voltage, this fault will occur.
Cause:
The ECU A-9000 is sensing too high a system voltage fluctuation.
Solution:
1. Verify that the fault is present and active.
Use the Electronic Service Tool (EST) to check the status of this fault.
A. If the fault is present and active, continues with Step 2.
B. If the fault is no longer present or in an inactive state, the fault may be intermittent and not currently active.
Continue with Step 4.
2. Check for related faults.
Use the EST to check for faults relative to low battery, control system voltage level or throttle valve actuator Z-9001.
A. If low voltage level faults are present, resolve those faults and then return to this fault.
B. If no low voltage level faults are present, continue with Step 3.
3. Check the ECU A-9000 for the appropriate software and re-flash, if necessary.
A. If the fault has been resolved, return the machine to service.
B. If the fault has not been resolved, escalate an ASIST concern.
4. Visually inspect the relevant harnesses and connectors for damage, bent or dislocated pins, corroded terminals,
or broken wires. Verify that the connectors are fully installed.
Flex the harnesses involved to reveal intermittent breaks or shorts in the wiring concerned.
Operate the machine while you monitor the display.
A. If you find damage or the display indicates other than normal display readings, then repair the damage discov-
ered during the inspection or locate and repair the other than normal display condition and verify that the error
has been resolved.
B. If you do not find damage and the display indicates only normal readings, then erase the fault code and continue
operation.
Electrical systems - FAULT CODES
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