Table 246
Troubleshooting Test Steps
Values Results
1. Check Connectors for Moisture and Corrosion
A. Inspect all the harnesses. Ensure that the routing of the wiring
harness allows the wires to enter the face of each connector at a
perpendicular angle. Otherwise, the wire will deform the seal bore.
This situation can create a path for the entrance of moisture. Verify
that the seals for the wires are sealing correctly.
B. Ensure that the sealing plugs are in place. If any of the plugs
are missing, replace the plug. Ensure that the plugs are inserted
correctly into the connector. Refer to Illustration 186 .
C. Disconnect the suspect connector and inspect the connector
seal. Ensure that the seal is in good condition. If necessary, re-
place the connector.
D. Thoroughly inspect the connectors for evidence of moisture
entry.
Note: Some minor seal abrasion on connector seals is normal. Mi-
nor seal abrasion will not allow the entry of moisture.
If moisture or corrosion is evident in the connector, the source of
the moisture entry must be found and repaired. If the source of the
moisture entry is not repaired, the fault will recur. Simply drying
the connector will not rectify the fault. Check the following items
for the possible moisture entry path:
· Missing seals
· Incorrectly installed seals
· Nicks in exposed insulation
· Improperly mated connectors
Moisture can also travel to a connector inside a wire. If moisture is
found in a connector, thoroughly check the connector harness for
damage. Also check other connectors that share the harness for
moisture.
Note: The ECM is a sealed unit. If moisture is found in an ECM
connector, the ECM is not the source of the moisture. Do not re-
place the ECM.
E. Check the connectors for white deposits. White deposits may
indicate that the connector has been contaminated with Diesel Ex-
haust Fluid (DEF).
DEF may corrode the copper wire in the wiring harness.
Harness,
connectors,
and seals are
OK.
Result: A fault has been found with the harness or the
connectors.
Repair: Repair the connectors or the wiring, as required. En-
sure that all the seals are correctly installed. Ensure that the
connectors have been reattached.
If corrosion is evident on the pins, sockets or the connector,
use only denatured alcohol to remove the corrosion. Use a
cotton swab or a soft brush to remove the corrosion.
If moisture was found in the connectors, run the engine for
several minutes and check again for moisture. If moisture re-
appears, the moisture is wicking into the connector. Even if
the moisture entry path is repaired, replacement of the wires
may be necessary.
Use the electronic service tool to clear all logged diagnostic
codes and then verify that the repair eliminates the fault.
Result: The harness, connectors, and seals are in good
condition.
Proceed to Test Step 2.
2. Check the Wires for Damage to the Insulation
A. Carefully inspect each wire for signs of abrasion, nicks, and
cuts.
Inspect the wires for the following conditions:
· Exposed insulation
· Rubbing of a wire against the engine
· Rubbing of a wire against a sharp edge
B. Check all the fasteners for the harness and the strain relief
components on the ECM to verify that the harness is correctly se-
cured. Also check all the fasteners to verify that the harness is not
compressed. Pull back the harness sleeves to check for a flat-
tened portion of wire. A fastener that has been overtightened flat-
tens the harness. This condition damages the wires that are inside
the harness.
The wiring is
OK
Result: There is damage to the harness.
Repair: Replace the harness.
Use the electronic service tool to clear all logged diagnostic
codes and then verify that the repair eliminates the fault.
Result: The wires are free of abrasion, nicks, and cuts and
the harness is correctly clamped.
Proceed to Test Step 3.
(continued)
514 UENR4469-36
Service
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