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 presen, t an Intermittent Condition is indicated.
|
Preliminary Checks
| Refer to Important Preliminary Checks in
Symptoms
.
|
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.
Check the suspect circuit for the following conditions:
| • | Poorly mated connectors |
| • | 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 (male to female connection) |
| | Checking for terminal retention requires the use of the J-38125
Terminal Repair Kit. Refer to
Wiring Repairs
in Wiring Systems. |
| • | Poor terminal to wire connection |
| | Checking 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 a digital multimeter (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).
|
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 typical Scan Tool Data List values or
data values taken from a similarly equipped known good vehicle. |
| | Also see the Vehicle Data Recorder information listed below. |
| • | 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 typical Scan Tool Data List values 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 (AF ECU, 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: |
| • | Ignition control (IC) wires routed near the generator or secondary
ignition system wires and components. |
| • | The ignition system secondary voltage shorted to ground. |
| • | Faulty control or ignition module grounds. |
| • | The MIL control circuit intermittently shorted to ground. |
|
Loss of DTC Memory
| In order to check 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 failure of the DTC to remain in memory may
indicate a faulty control module.
|
Additional Checks
| Check for open
diodes (A/C clutch, etc.) that may cause electrical interference.
|
Vehicle Data Recorder
| The Vehicle Data Recorder J 42598
is connected to the DLC and sent with the customer. The vehicle
data recorder captures data for later retreival and analysis by the technician.
Refer to the vehicle data recorder user instructions for more information.
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