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
.
|
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:
| • | 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 (male to female connection). |
| | Checking for terminal retention requires the use of the J-38125
Terminal Repair Kit. |
| • | 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 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).
|
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 (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. |
| • | Poor 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 for 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.
|
