Checks
| Action
|
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.
|
Preliminary Checks
| Refer to Important Preliminary
Checks in
Symptoms - Engine Controls
.
|
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 -- backed out. |
| • | Terminals not properly formed or damaged -- usually due to
improper diagnostic probing procedures. |
| • | Poor terminal retention. |
| | 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.
|
Scan Tool
| The scan tool features that can be used to locate an intermittent
conditions source include the following:
| • | 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 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: |
| • | 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:
- 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.
|
Additional Checks
| Test for open diodes -- A/C clutch, etc. --
that may cause electrical interference.
|
Vehicle Data Recorder
| The J 42598
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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