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When Monitored:
While the engine is running.
Set Condition:
Battery voltage is less than 11.5 volts for more than 8 seconds. Battery voltage must exceed 12 volts for more
than 5 seconds for fault to become inactive.
Possible Causes
OTHER DTC’S PRESENT
DIRTY OR LOOSE CONNECTIONS
ADD-ON OR ACCESSORY WIRES AT BATTERY TERMINAL
HIGH RESISTANCE IN THE B+ CIRCUIT
HIGH RESISTANCE IN THE B+ CROSS OVER CABLE
HIGH RESISTANCE IN THE GROUND CIRCUIT
GENERATOR
ECM
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.OTHER DTC’S PRESENT
With the scan tool, read DTCs.
Is DTC P2502 set?
Ye s>>
Repair other DTC’s first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.DIRTY OR LOOSE CONNECTIONS
Visually inspect the positive and negative connections at the battery.
Visually inspect the battery negative connections at the engine block.
Are the connections free of corrosion and are they tight?
Ye s>>
Go To 3
No>>
Clean and/or tighten the connections.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
3.ADD-ON OR ACCESSORY WIRES AT BATTERY TERMINAL
Check for add-on or accessory wiring at positive (+) terminal of the battery.
Are there any damaged wires at the battery?
Ye s>>
Remove defective or miss wired add-on or accessory wiring from battery.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 4
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4.HIGH RESISTANCE IN THE B+ CIRCUIT
Measure the voltage between the B+ post of the generator and the B+ post of the battery while the engine is run-
ning.
Is the voltage above .4 volts?
Ye s>>
Repair the high resistance in the B+ circuit from battery to the generator.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 5
5.HIGH RESISTANCE IN THE B+ CROSS OVER CABLE
Measure the voltage between the B+ post of the generator and the B+ post of the right side battery to the left side
battery while the engine is running.
Is the voltage above .4 volts?
Ye s>>
Repair the high resistance in the B+ cross over cable from right side battery to left side battery.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 6
6.HIGH RESISTANCE IN THE GROUND CIRCUIT
Measure the voltage between the generator case and the B- post of the battery.
Is the voltage above .1 volts?
Ye s>>
Repair the high resistance in the ground circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 7
7.GENERATOR
Disconnect the Generator field harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the generator field terminals at the
generator.
Is the resistance between .5 and 15 Ohms?
Ye s>>
Go To 8
No>>
Replace the generator.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
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8.ECM
Measure and record the voltage between battery positive circuit of the
ECM harness connector and the battery negative circuits of the ECM
harness connector.
Reconnect the ECM connectors.
Use the scan tool to measure and record battery voltage.
Compare the voltage reading from the voltmeter with that of the scan
tool.
Are the readings within 3 volts of each other?
Ye s>>
Refer to the INTERMITTENT CONDITION Symptom (Diag-
nostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS
AND TESTING)
No>>
Replace and program the ECM in accordance with the Ser-
vice Information.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
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P2509-POWERDOWN DATA LOST ERROR
For a complete wiring diagramRefer to Section 8W.
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When Monitored:
Continuous - key on or key off.
Set Condition:
Loss of voltage detected at the ECM for a calibrated amount of time.
Possible Causes
POOR CONNECTIONS AT THE BATTERIES
LOW BATTERY VOLTAGE
OPEN FUSED B+ TO ECM
OPEN GROUND CIRCUIT
BATTERY + SHORTED TO OTHER CIRCUITS
RETURN CIRCUIT SHORTED
BATTERY + SHORTED TO GROUND
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.POOR CONNECTIONS AT THE BATTERIES
Visually inspect the wiring at the battery for damaged wires, or corrosion.
Are the connections tight and free of corrosion?
Ye s>>
Go To 2
No>>
Repair the poor connections at the batteries.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
2.L O W B AT T E RY V O LTA G E
Measure the voltage between the positive and negative posts of the batteries.
Is the battery voltages both above 12 volts?
Ye s>>
Go To 3
No>>
Recharge or replace the battery (s).
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
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3.OPEN FUSED B+ TO ECM
Turn the ignition off.
Disconnect the ECM harness connectors.
Turn the ignition on.
Measure the resistance between the positive battery post and the ECM
supply circuits.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 4
No>>
Repair the open fused B+ circuit to ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
4.OPEN GROUND CIRCUIT
Measure the resistance between the negative battery post and the ECM
ground circuits.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 5
No>>
Repair the open ground circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
5.BATTERY + SHORTED TO OTHER CIRCUITS
Measure the resistance between the ECM supply circuits and all other
circuits in the ECM harness connector, except other supply circuits.
Is the resistance greater than 100k Ohms?
Ye s>>
Go To 6
No>>
Repair the battery circuit short to other circuits in engine
harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
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6.RETURN CIRCUIT SHORTED
Measure the resistance between the ECM return circuits and all other
circuits in the ECM harness connector, except other return circuits.
Is the resistance greater than 100k Ohms?
Ye s>>
Go To 7
No>>
Repair or replace the engine harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
7.BATTERY + SHORTED TO GROUND
Measure the resistance between the ECM B+ supply circuits and
ground.
Is the resistance greater than 100k Ohms?
Ye s>>
Refer to the INTERMITTENT CONDITION Symptom (Diag-
nostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS
AND TESTING)
No>>
Repair Battery + shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 872 of 5267
P2607-LOW VOLTAGE AT THE #2 INTAKE AIR HEATER RELAY
For a complete wiring diagramRefer to Section 8W.