6.7L Cummins Forum

Here's what the P2509-ECM/PCM POWER INPUT SIGNAL INTERMITTENT means to us 6.7L Cummins owners


The ECM receives a constant voltage from the batteries through the unswitched battery wires that are connected directly to the positive (+) battery post. The ECM receives switched battery input through the vehicle Ignition Switch wire when the vehicle is turned on. The ECM will illuminate the MIL lamp immediately after the diagnostic runs and fails. During the time the customer may experience some performance effects such as engine dying or hard starting. Fault information, trip information could be inaccurate. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

• When Monitored: Continuous - key on or key off.
• Set Condition: Loss of voltage detected at the ECM for a calibrated amount of time. Supply voltage to the PCM fell below 6.2 volts momentarily or the ECM was not allowed to power down correctly (retain battery voltage for 30 seconds after key off).

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
DEFECTIVE BATTERY


Here are some things you can do to troubelshoot it.

The first thing you should do if this is the first time seeing the code is clear the code and see if it wasn't just a hiccup. If it comes back then try the following:


1. POOR CONNECTIONS AT THE BATTERIES

Visually inspect the wiring at the battery for damaged wires, or corrosion.

2. LOW BATTERY VOLTAGE/ DEFECTIVE BATTERY

Check for dead cells/low voltage
Charge/Replace the batteries

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.

Resistance should be less then 10 Ohms

If not, Repair the open fused B+ circuit to ECM.


4. OPEN GROUND CIRCUIT
Measure the resistance between the negative battery post and the ECM ground circuits.

The resistance should be less than 10 Ohms

If not, repair the open ground circuit.

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.

The resistance should be greater than 100k Ohms?

If not, repair the battery circuit short to other circuits in engine harness.

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.

The resistance should be greater than 100k Ohms?

If not, repair or replace the engine harness.

7. BATTERY + SHORTED TO GROUND

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

The resistance should be greater than 100k Ohms?

If not, Repair Battery + shorted to ground.

Attached Thumbnails

 

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2007.5 Dodge Ram 3500 HD,QC, 6.7L Cummins, 6speed Auto, 4X4, Bighorn Edition.
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