Inspection or Test
| Action
|
DEFINITION: The problem is not currently present but is indicated in DTC History.
OR
There is a customer complaint, but the symptom can not currently be duplicated,
if the problem is not DTC related.
|
Preliminary
| Perform the
Diagnostic System Check - Vehicle
in Vehicle DTC Information before starting.
|
Harness or Connector
| Many intermittent open or shorted circuits are affected by harness/connector
movement that is caused by the following conditions:
| • | Bumps or rough pavement |
Test for intermittents by performing the applicable procedure from the following
list:
| • | Move related connectors and wiring while monitoring the appropriate scan
tool data. |
| • | Move related connectors and wiring with the component commanded ON and
OFF, with the scan tool--Observe the component operation. |
| • | With the engine running, move related connectors and wiring while monitoring
engine operation. |
Verify whether the harness or connector movement affects any of the following
systems:
| • | Component or system operation |
Repair the components as necessary. Refer to Electrical Connections or Wiring
in this table.
|
Electrical Connections or Wiring
| Many intermittent open or shorted circuits are affected by harness/connector
movement that is caused by the following conditions:
| • | Bumps or rough pavement |
Test for intermittents by performing the applicable procedure from the following
list:
| • | Move related connectors and wiring while monitoring the appropriate scan
tool data. |
| • | Move related connectors and wiring with the component commanded ON and
OFF, with the scan tool. Observe the component operation. |
| • | With the engine running, move related connectors and wiring while monitoring
engine operation. |
If harness or connector movement affects the data displayed, component/system
operation, or engine operation, inspect and repair the harness/connections as necessary.
|
Control Module Power and Grounds
Component Power and Grounds
| Poor power or ground connections can cause widely varying symptoms.
| • | Test all control module power circuits. Many vehicles have multiple circuits
supplying power to the control module. Other components in the system may have separate
power circuits that may also need to be tested. Inspect connections at the module
or component connectors, fuses, and any intermediate connections between the power
source and the module or component. A test lamp or a DMM may indicate that voltage
is present, but neither tests the ability of a circuit to carry sufficient current.
Ensure that the circuit can carry the current necessary to operate the component.
Refer to
Power Distribution Schematics
in
Wiring Systems. |
| • | Test all control module ground and system ground circuits. The control
module may have multiple ground circuits. Other components in the system may have
separate grounds that may also need to be tested. Inspect grounds for clean and tight
connections at the grounding point. Inspect the connections at the component and in
splice packs, where applicable. Ensure that the circuit can carry the current necessary
to operate the component. Refer to
Ground Distribution Schematics
in Wiring Systems. |
|
Temperature Sensitivity
|
| • | An intermittent condition may occur when a component or connection reaches
normal operating temperature. The condition may occur only when the component or connection
is cold, or only when the connection is hot. |
| • | The following data may help to diagnose this type of intermittent condition: |
| - | Freeze Frame and Failure Records |
| • | If the intermittent is related to heat, review the following data: |
| - | High ambient temperatures |
| - | Underhood or engine generated heat |
| - | Circuit generated heat due to a poor connection, or high electrical load |
| - | Higher than normal load conditions, such as towing |
| • | If the intermittent is related to cold, review the following data: |
| - | Low ambient temperatures--In extremely low temperatures, ice may
form in a connection or component. Test for water intrusion. |
| - | The condition only occurs on a cold start. |
| - | The condition is not present after the vehicle warms up. |
| • | Information from the customer may help to determine if the trouble follows
a pattern that is temperature related. |
|
Electromagnetic Interference (EMI) and Electrical Noise
| Some electrical components or circuits are sensitive to electromagnetic interference
(EMI) or other types of electrical noise. Perform the following procedures:
| • | Inspect for a misrouted harness that is too close to a high voltage or
high current device. This condition may induce electrical noise on a circuit that
could interfere with normal circuit operation. Inspect for wires that are too close
to the following devices: |
| - | Secondary ignition components |
| • | Determine whether the electrical system interference is caused by a malfunctioning
relay, powertrain control module (PCM) driven solenoid or switch. These components
may cause a sharp electrical surge. Normally, the problem will occur when the malfunctioning
component is operating. |
| • | Determine whether non-factory or aftermarket add-on accessories are installed
in the vehicle. These accessories may lead to an emission related OBD II failure.
Determine if any of the following non-factory or aftermarket add-on accessories is
causing the intermittent: |
| • | Test for an open diode across the AC compressor clutch and for other open
diodes. Some relays may contain a clamping diode. |
| • | If a DTC is determined to be intermittent, and the tests in this section
do not reveal a problem. Refer to Electrical Connections or Wiring in this table. |
|
Incorrect PCM Programming
|
| • | There are only a few situations when reprogramming a PCM is appropriate,
such as the following: |
| - | A new service PCM is installed. |
| - | A PCM from another vehicle is installed. |
| - | Revised software or calibration files have been released for this vehicle. |
| | Important: DO NOT re-program the PCM with the SAME
software or calibration files that are already present in the PCM. This is not an
effective repair for any type of driveability problem.
|
| • | Verify that the PCM contains the correct software or calibration. If incorrect
programming is found, reprogram the PCM with the most current software or calibration.
Refer to
Service Programming System (SPS)
in Programming and Setup. |
|
Duplicating Failure Conditions
|
| • | If none of the previous tests are successful, attempt to duplicate or
capture the failure conditions. |
| • | Freeze Frame and Failure Records data, where applicable, contains the
conditions that were present when the DTC set. Perform the following procedure: |
| 1. | Review and record Freeze Frame and Failure Records data. |
| 2. | Clear the DTCs using the scan tool. |
| 3. | Turn the key to OFF and wait 15 seconds. |
| 4. | Operate the vehicle under the same conditions that were noted in Freeze
Frame and Failure Records data, as closely as possible. The vehicle must also be operating
within the Conditions for Running the DTC. Refer to Conditions for Running the DTC
in the supporting text of the DTC being diagnosed. |
| 5. | Monitor DTC Status for the DTC being tested. The scan tool will indicate
Ran, when the enabling conditions have been satisfied long enough for the DTC to run.
The scan tool will also indicate whether the DTC passed or failed. |
| • | An alternate method is to drive the vehicle with the DMM connected to
a suspected circuit. An abnormal reading on the DMM when the problem occurs, may help
you locate the problem. |
|
Scan Tool Snapshot
| The scan tool can be set up to take a snapshot of the parameters available via
serial data. The snapshot function records live data over a period of time. The recorded
data can be played back and analyzed. The scan tool can also graph parameters singly
or in combinations of parameters for comparison. The snapshot can be triggered manually
at the time the symptom is noticed, or set up in advance to trigger when a DTC sets.
An abnormal value captured in the recorded data may point to a system or component
that needs to be investigated further.
Refer to the scan tool user instructions for more information on the Snapshot
function.
|
Vehicle Data Recorder
| The J 42598
or J-42598-B
Vehicle Data Recorder is
connected to the data link connector (DLC) and sent with the customer. The J 42598
or J-42598-B
captures data for later retrieval and analysis
by the technician. Refer to the vehicle data recorder user instructions for more information.
|
