Checks
| Action
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DEFINITION: The
problem may or may not turn ON the MIL or store a DTC. If a DTC was stored
and the DTC diagnostic table indicates the fault is not present
an Intermittent Condition is indicated.
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Preliminary Checks
| Refer to Important
Preliminary Checks in
Symptoms - Engine Controls
.
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Electrical Connections or Wiring
| Electrical connections and wiring cause most intermittent
conditions.
Determine which circuit is suspected of having an intermittent condition.
This may be indicated by DTCs with a fault not present.
Inspect the suspect circuit for the following conditions:
| • | Connectors poorly mated. |
| • | Terminals not fully seated in the connector. |
| • | Terminals not properly formed or damaged, usually due to improper
diagnostic probing procedures. |
| • | Poor terminal retention - male to female connection. |
| | Testing for terminal retention requires the use of the J-38125
Terminal Repair Kit. |
| • | Poor terminal to wire connection. |
| | Inspecting for poor terminal to wire connection requires removing the
wire/terminal from the connector body. |
|
Road Test
| Drive the vehicle while
monitoring the suspect circuit with the scan tool or the J 39200
DMM connected to the circuit. An
abnormal voltage or scan tool reading indicates the suspect circuit
and a possible circuit condition - open or shorted circuit.
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Scan Tool
| The scan tool features that can be used to locate an intermittent conditions
source include the following items:
| • | Scan tool snapshot feature |
| | The scan tool snapshot feature can be triggered to capture and store
engine parameters when a malfunction occurs. This stored information can
be reviewed and compared to the Engine Scan Tool Data List or data
values taken from a similarly equipped known good vehicle. |
| • | Freeze Frame/Failure Records data feature |
| | Freeze Frame/Failure Records are stored when certain DTCs set. They
typically include information to aid in reproducing the driving conditions
that were present when a DTC is stored. In addition, engine parameters
are also stored. This stored information can be reviewed and
compared to the Engine Scan Tool Data List or data values taken
from a similarly equipped known good vehicle. |
| | Freeze Frame/Failure Records data will be erased when DTC information
is cleared either by scan tool clearing or by disconnection of the Control
modules (Alternative Fuels ECM, VCM / PCM or ECM) power supply. |
|
Intermittent Malfunction Indicator Lamp (MIL)
| The following conditions may cause intermittent
MIL operation with no DTCs stored:
| • | A defective relay, Control Module driven solenoid, or a switch
that causes electrical system interference. Usually the symptom will occur
when the faulty component is operating. |
| • | The improper installation of add-on electrical devices. These
can include the following items: |
| • | Ignition control (IC) wires routed near the generator or secondary
ignition system wires and components. |
| • | The ignition system secondary voltage shorted to ground. |
| • | Poor control or ignition module grounds. |
| • | The MIL control circuit intermittently shorted to ground. |
|
Loss of DTC Memory
| In order to test for proper DTC Memory function, perform the following
procedures:
- Observe the Conditions For Running The DTC for the TP Sensor Circuit
Low Voltage DTC.
- Disconnect the TP sensor connector.
- Operate the vehicle within the Conditions For Running The DTC.
- The MIL should illuminate upon completion of all the Conditions
For Running The DTC. Two key cycles or drive trips may be required.
- A TP Sensor Circuit Low Voltage DTC should be stored in the Control
Module and remain in memory when the ignition is turned OFF.
Failure to store a DTC or for the DTC to remain in memory may indicate
a faulty Control module.
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Additional Checks
| Test for open diodes - A/C clutch, etc. that may
cause electrical interference.
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Vehicle Data Recorder
| The Vehicle Data Recorder is connected
to the data link connector (DLC) and sent with the customer. The captures
data for later retrieval and analysis by the technician. Refer to
the vehicle data recorder user instructions for more information.
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