P2509
 

the dumb stealerships said that my bullydog caused this CEL... What would cause this for real. As soon as they see me pull in they already thought about their answer to my problems, "bullydog caused it"! Any help???

The code is low voltage to the ECM. Here's some info:

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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.

DIAGNOSTIC TEST

1. POOR CONNECTIONS AT THE BATTERIES
Visually inspect the wiring at the battery for damaged wires, or corrosion.

Q: 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). See: Verification Tests\Powertrain Verification Test Ver - 1

2. LOW BATTERY VOLTAGE
Measure the voltage between the positive and negative posts of the batteries.

Q: 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). See: Verification Tests\Powertrain Verification Test Ver - 1

3. OPEN FUSED B+ TO ECM

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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.

Q: 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). See: Verification Tests\Powertrain Verification Test Ver - 1

4. OPEN GROUND CIRCUIT

http://i150.photobucket.com/albums/s...0Info/06-3.gif

Measure the resistance between the negative battery post and the ECM ground circuits.

Q: Is the resistance less than 10 Ohms?

YES: Go To 5
NO: Repair the open ground circuit. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test Ver - 1

5. BATTERY + SHORTED TO OTHER CIRCUITS

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Measure the resistance between the ECM supply circuits and all other circuits in the ECM harness connector, except other supply circuits.

Q: 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). See: Verification Tests\Powertrain Verification Test Ver - 1

6. RETURN CIRCUIT SHORTED

http://i150.photobucket.com/albums/s...0Info/06-5.gif

Measure the resistance between the ECM return circuits and all other circuits in the ECM harness connector, except other return circuits.

Q: 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). See: Verification Tests\Powertrain Verification Test Ver - 1

7. BATTERY + SHORTED TO GROUND

http://i150.photobucket.com/albums/s...0Info/06-6.gif

Measure the resistance between the ECM B+ supply circuits and ground.

Q: Is the resistance greater than 100k Ohms?

YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). See: Initial Inspection and Diagnostic Overview\Diagnostic Strategies
NO: Repair Battery + shorted to ground. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test Ver - 1