P2509 POWERDOWN DATA LOST ERROR

When Monitored and Set Condition:

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

DIAGNOSTIC PROCEDURE

NOTE: Refer to VERIFICATION TESTS for appropriate verification test procedures.

1. Visually inspect the wiring at the battery for damaged wires, or corrosion. Are the connections tight and free of corrosion?
   Yes --> Go To 2
   No --> Repair the poor connections at the batteries. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
2. Measure the voltage between the positive and negative posts of the batteries. Is the battery voltages both above 12 volts?
   Yes --> Go To 3
   No --> Recharge or replace the battery (s). Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
3. 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?
   Yes --> Go To 4
   No --> Repair the open fused B+ circuit to ECM. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
4. Measure the resistance between the negative battery post and the ECM ground wire. Is the resistance less than 10 Ohms?
   Yes --> Go To 5
   No --> Repair the open ground circuit. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
5. 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?
   Yes --> Go To 6
   No --> Repair the battery circuit short to other circuits in engine harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
6. 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?
   Yes --> Go To 7
   No --> Repair or replace the engine harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
7. Measure the resistance between the ECM B+ supply circuit and ground. Is the resistance greater than 100k Ohms?
   Yes --> Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Repair Battery + shorted to ground. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).