Troubleshooting

Table 65
Troubleshooting Test Steps
Values Results
1. Check for Active or Recently Logged Diagnostic Codes
A. Connect the electronic service tool to the diagnostic connector.
Refer to Troubleshooting, “Electronic Service Tools”.
B. Turn the keyswitch to the ON position. If the engine will start,
then run the engine.
C. Monitor the electronic service tool for active and/or recently
logged diagnostic codes.
D. Turn the keyswitch to the OFF position.
Diagnostic
codes
Result: A 1221-2 diagnostic code is active or recently
logged.
Repair: Make a note of all other active or recently logged di-
agnostic codes. Troubleshoot all other codes before continu-
ing this procedure. Refer to Troubleshooting, “Diagnostic
Trouble Codes”.
If 1221-2 is the only active or recently logged diagnostic
code, proceed to Test Step 2.
Result: A 152-2 diagnostic code is active or recently logged.
Repair: Make a note of all other active or recently logged di-
agnostic codes. Troubleshoot all other codes before continu-
ing this procedure. Refer to Troubleshooting, “Diagnostic
Trouble Codes”.
If 152-2 is the only active or recently logged diagnostic code,
proceed to Test Step 3.
Result: A 166-X or 2840-12 diagnostic code is active or re-
cently logged.
Proceed to Test Step 4.
2. Clear the Diagnostic Code and Attempt to Start the Engine
A. Use the electronic service tool to clear the 1221-2 diagnostic
code.
B. Turn the keyswitch to the ON position. If the engine will start,
then run the engine for at least 10 minutes.
C. Operate the engine over the full duty cycle to replicate the con-
ditions in which the fault occurred.
D. Stop the engine. Turn the keyswitch to the ON position.
E. Use the electronic service tool to check for an active or recently
logged 1221-2 diagnostic code.
1221-2 diag-
nostic code
Result: The 1221-2 diagnostic code is no longer active.
Return the engine to service.
Result: The 1221-2 diagnostic code is still active.
Proceed to Test Step 3.
3. Check the Battery Supply Voltage to the ECM
A. Check that the ECM is receiving the correct battery voltage. Re-
fer to Troubleshooting, “Electrical Power Supply - Test”.
Battery
voltage
Result: The ECM is receiving the correct voltage.
Proceed to Test Step 4.
Result: Make any necessary repairs. Refer to Troubleshoot-
ing, “Electrical Power Supply - Test”.
Use the electronic service tool to clear all logged diagnostic
codes and verify that the repair eliminates the fault.
If the diagnostic code is still active, proceed to Test Step 4.
(continued)
UENR0612-07 129
Circuit Tests
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