Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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26.
DTC P0480 ECU Fan I control wire is open
P0481
ECU Fan II control wire is open.
P0483 ECU Fan I control wire internal drive module is overheated.
P0484 ECU Fan II control wire internal drive module is overheated.
P0691 ECU Fan I control wire is short to ground.
P0692
ECU Fan I control wire is short to high level.
P0693 ECU Fan II control wire is short to ground.
P0694 ECU Fan II control wire is short to high level.
Fault Description: ECU provides low-speed relay with grounding via so-called “drive” internal solid component in
order to control cooling fan low speed operation. For cooling fan high speed operation, ECU adopts the method of
high speed and S/P replay control circuit grounding with simultaneous low-speed control circuit grounding. Battery
positive voltage is provided to low-speed, high-speed and S/P fan relays. When ECU commands fan relay to be
connected, control circuit voltage is low level which is close to 0V. When ECU commands fan relay to be
disconnected, control circuit voltage should be high level which is close to battery voltage. ECU monitors relay
control circuit for conditions as follows:
It is short to ground.
It is short to voltage.
It is open.
When ECU detects incorrect voltage in low-speed or high-speed drive circuit, DTC occurs and corresponding drive
will stop operating.
Cooling Fan Relay I control circuit controls low-speed cooling fan relay.
Cooling Fan Relay II control circuit controls high-speed cooling fan relay.
Diagnosis Hint: Check harness for intermittency and good contact.
Prior to maintenance, remove all fragments from connector surface. Check connector pads for correct installation to
prevent contamination from entering prior to diagnosis and component replacement.
z Poor terminal connection—Check harness connectors for looseness, mismatching, retainer damage, improper
shape or damage and connection failure with wires. Apply corresponding matching terminals for test of proper
tension.
z Harness damage—Check wire harness for damage. In the case of no harness faults, move relevant connectors and
wire harness and observe display of fault diagnostic apparatus. Fault diagnostic apparatus displays changes to
indicate fault positions.
z Check ECU and engine ground connection for reliability and cleanness. If it is determined that DTC is an
intermittent fault, please refer to Fault Record to check the time of last DTC occurrence.
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