Inspection/Test
| Action
|
DEFINITION: The condition 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 condition is not DTC related.
|
Preliminary
| Refer to
Symptoms - Engine Controls
before starting.
|
Harness/Connector
| Many intermittent open or shorted circuits come and go with harness/connector
movement caused by vibration, engine torque, bumps/rough pavement, etc.
Test for this type of condition 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. Refer to Electrical Connections or Wiring in this table.
|
Electrical Connections or Wiring
|
| • | Poor electrical connections/terminal tension or wiring conditions cause
most intermittents. Perform a careful inspection of the suspected circuit
for the following: |
| - | Inspect for poor mating of the connector halves, or terminals not fully
seated in the connector body (backed-out). |
| - | Inspect for improperly formed or damaged terminals. Test for poor terminal
tension. |
| - | Inspect for poor terminal to wire connections including terminals crimped
over insulation. This requires removing the terminal from the connector body. |
| - | Inspect for corrosion/water intrusion. Pierced or damaged insulation can
allow moisture to enter the wiring. The conductor can corrode inside the insulation,
with little visible evidence. Look for swollen and stiff sections of wire
in the suspect circuits. |
| - | Inspect for wires that are broken inside the insulation. |
| - | Inspect the harness for pinched, cut or rubbed through wiring. |
| - | Ensure that the wiring does not come in contact with hot exhaust components. |
|
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/component connectors, fuses, and any intermediate connections
between the power source and the module/component. A test lamp or a DMM may
indicate that voltage is present, but neither tests a circuit ability 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/connection reaches
normal operating temperature. The condition may occur only when the component/connection
is cold, or only when the component/connection is hot. |
| • | Freeze Frame, Failure Records, Snapshot, or Vehicle Data Recorder data
may help with this type of intermittent condition, where applicable. |
| • | If the intermittent is related to heat, review the data for a relationship
with the following: |
| - | High ambient temperatures |
| - | Underhood/engine generated heat |
| - | Circuit generated heat due to a poor connection, or high electrical load |
| - | Higher than normal load conditions (towing, etc.) |
| • | If the intermittent is related to cold, review the data for the following: |
| - | 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 goes away when 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/circuits are sensitive to electromagnetic interference
(EMI) or other types of electrical noise. Inspect for the following conditions:
| • | A mis-routed harness that is too close to high voltage/high current devices
such as secondary ignition components, motors, generator etc. These
components may induce electrical noise on a circuit that could interfere
with normal circuit operation. |
| • | Electrical system interference caused by a malfunctioning relay, powertrain
control module (PCM) driven solenoid or switch. These conditions can cause a sharp
electrical surge. Normally, the condition occurs when the malfunctioning
component is operating. |
| • | Improper installation of non-factory or aftermarket add on accessories
such as lights, 2-way radios, amplifiers, electric motors, remote starters,
alarm systems, cell phones, etc. these accessories may lead to an emission related
OBD II failure while in use, but do not fail when the accessories are not
in use. Refer to
Checking Aftermarket Accessories
in Wiring Systems. If a DTC is determined to be intermittent, and the tests in this
section do not reveal a condition, refer to Vehicle Data Recorder later in this table. |
| • | Test for an open diode across the A/C compressor clutch and for other
open diodes. Some relays may contain a clamping diode. |
|
Incorrect PCM Programming
|
| • | There are only a few situations where reprogramming a PCM is appropriate: |
| - | A new service PCM is installed. |
| - | A PCM from another vehicle is installed. |
| - | Revised software/calibration files have been released for this vehicle. |
| | Important:: DO NOT re-program the PCM with the SAME software/calibration files that are
already present in the PCM. This is not an effective repair for any type of
driveability condition.
|
| • | Verify that the PCM contains the correct software/calibration. If incorrect
programming is found, reprogram the PCM with the most current software/calibration.
Refer to
Service Programming System (SPS)
in Programming. |
|
Duplicating Failure Conditions
|
| • | If none of the previous tests are successful, attempt to duplicate and/or
capture the failure conditions. |
| • | Freeze Frame/Failure Records data, where applicable, contains the conditions
that were present when the DTC set. |
| 1. | Review and record Freeze Frame/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/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 indicates Ran,
when the enabling conditions have been satisfied long enough for
the DTC to run. The scan tool also indicates 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 condition occurs,
may help you locate the condition. |
|
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
Vehicle Data
Recorder is connected to the data link connector (DLC) and sent with the customer.
The J 42598
captures data
for later retrieval and analysis by the technician. Refer to the vehicle
data recorder user instructions for more information.
|
