Doosan D20S-5 Operation & Maintenance Manual page 130

Operation Section
INTERMITTENT
Checks
DEFINITION: The problem may or may not turn ON the (MIL) or store a Diagnostic Trouble Code (DTC).
Preliminary Checks
Faulty Electrical
Connections
or Wiring
Operational Test
Intermittent MIL
Illumination
Loss of DTC
Memory
Do not use the DTC tables. If a fault is an intermittent, the use of the DTC tables
with this condition may result in the replacement of good parts.
Faulty electrical connections or wiring can cause most intermittent problems.
Check the suspected circuit for the following conditions:
• Faulty fuse or circuit breaker, connectors poorly mated, terminals not fully seated
in the connector (backed out). Terminals not properly formed or damaged.
• Wire terminals poorly connected.
• Terminal tension is insufficient.
• Carefully remove all the connector terminals in the problem circuit in order to
ensure the proper contact tension.
• If necessary, replace all the connector terminals in the problem circuit in order to
ensure the proper contact tension (except those noted as "Not Serviceable"). See
section Wiring Schematics.
• Checking for poor terminal to wire connections requires removing the terminal
from the connector body.
If a visual and physical check does not locate the cause of the problem, operate the
vehicle with the DST connected. When the problem occurs, an abnormal voltage or
scan reading indicates a problem circuit.
The following components can cause intermittent MIL and no DTC(s):
• A defective relay.
• Switch that can cause electrical system interference. Normally, the problem will
occur when the faulty component is operating.
• The improper installation of add on electrical devices, such as lights, 2-way
radios, electric motors, etc.
• The ignition secondary voltage shorted to a ground.
• The MIL circuit or the Diagnostic Test Terminal intermittently shorted to ground.
• The MIL wire grounds.
To check for the loss of the DTC Memory:
1. Disconnect the TMAP sensor.
2. Idle the engine until the MIL illuminates.
3. The ECM should store a TMAP DTC which should remain in the memory when
the ignition is turned OFF. If the TMAP DTC does not store and remain, the ECM
is faulty.
Action
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