The P2509: ECM/PCM Power Input Signal Intermittent code indicates an intermittent power input signal to the Engine Control Module (ECM) or Powertrain Control Module (PCM). This can cause the vehicle’s engine to stall or fail to start, as the ECM/PCM is responsible for managing various critical engine functions. The intermittent signal suggests irregularities in the power supply, which could stem from issues with the vehicle’s battery, wiring, or other electrical components.
P2509 quick overview
| Description | P2509: ECM/PCM Power Input Signal Intermittent |
| Is it serious? | This code can be serious as it may lead to vehicle stalling or failure to start. |
| Possible causes | – Weak or failing batteries – Poor battery connections – Faulty or damaged wiring harness – Faults in the Powertrain Control Module (PCM) or Engine Control Module (ECM) – Issues with the alternator or charging system – Problems with the Totally Integrated Power Module (TIPM) |
| How to diagnose? | Check Battery Condition: Test the vehicle’s batteries to ensure they are holding a charge and delivering sufficient power. Inspect Battery Connections: Look for loose, corroded, or damaged connections at the battery terminals. Examine Wiring Harness: Check the wiring harness for signs of damage, wear, or loose connections, particularly around the PCM/ECM. Test Alternator: Verify the alternator is functioning correctly and providing the necessary charge to the battery. Inspect PCM/ECM: Check the Powertrain Control Module or Engine Control Module for any signs of damage or malfunction. Analyze TIPM: Examine the Totally Integrated Power Module for any faults or issues. |
P2509 Meaning
This code means your car’s computer, which controls the engine, isn’t getting consistent power. This can cause your car to have trouble starting or even stall while driving. It’s usually due to problems with the car’s battery, electrical wiring, or the computer itself. It’s important to fix this to avoid starting issues and keep your car running smoothly.
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How to fix P2509 – learn from mechanics
I looked into P2509 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Dodge
Vehicle Information: 2006 Dodge Ram 2500 SLT 5.9L
Issue + Repair History:
- Check Engine Light on
- Substantial lugging when put in gear
- Fan clutch replacement did not solve the issue
Other OBD2 Codes + Test Results:
- P2509: ECM power input signal intermittent
Suggestions to Fix Issue:
- Check battery and charging system
- Inspect torque converter
- Verify the operation of the TIPM (Totally Integrated Power Module)
- Test for bad connections or faulty wiring
Final Fix:
- Replaced torque converter and performed a transmission fluid flush, resolving the issue.
Case #2: Dodge
Vehicle Information: 2005 Dodge Ram 3500 SLT 5.9L
Issue + Repair History:
- Poor fan speed on start
- High side A/C pressure goes over 400 psi, causing A/C shutdown
- Scanner showing zero fan speed and control percentage
Other OBD2 Codes + Test Results:
- P0480: Fan Control 1 Control Circuit
- P0483: Fan Speed
- P0533: A/C Pressure High
- P0243: Wastegate
- P2509: ECM/PCM Power Supply Intermittent
Suggestions to Fix Issue:
- Check front fuse box for issues with fan circuit
- Inspect fan clutch
- Check A/C pressure transducer, as it commands the high & low fans
Final Fix:
- Replaced the fuse panel and fan clutch, addressing the issue with the fan control.
Case #3: Dodge
Vehicle Information: 2004 Dodge Ram 3500 ST 5.9L
Issue + Repair History:
- No start condition
- Check engine light on with several codes
Other OBD2 Codes + Test Results:
- P0477: Low Voltage on Engine Brake Driver
- P2127: Throttle Validation Switch Low
- P2509: ECM PCM Power Supply Intermittent
- P2503: Charging System Output Low
Suggestions to Fix Issue:
- Check and reseat all PCM connectors
- Consider replacing PCM if necessary
- Inspect battery connections and charging system
- Verify alternator functionality
- Examine all vehicle grounds for issues
Final Fix:
- Replaced the APP (Accelerator Pedal Position) sensor assembly. The part was sourced from a California dealership, likely one of the last factory parts available for this model.
Case #4: Dodge
Vehicle Information: 2007 Dodge Ram 2500 TRX4 5.9L
Issue + Repair History:
- Truck occasionally stalls and starts intermittently.
- Only code stored: P2509 (ECM power loss).
Other OBD2 Codes + Test Results:
- P2509: ECM power loss
Suggestions to Fix Issue:
- Check for any codes in the wireless control module (WCM) and observe the security light for issues with key chips.
- Scope all power inputs to the PCM to check for any dropouts indicating internal PCM faults.
- Investigate battery health more thoroughly, considering their age.
- Scope alternator charging for high in-rush voltage or charging rate, indicating high resistance in batteries.
- Consider the possibility of a bad crank sensor.
Final Fix:
- Replaced the batteries, resolving the issue. The truck has been trouble-free since.
Case #5: Dodge
Vehicle Information: 2007 Dodge Ram 3500 ST 6.7L
Issue + Repair History:
- Vehicle had no power while accelerating.
- Eight codes appeared simultaneously upon cranking: P2262, P0471, P0102, P1193, P2228, P2229, P2580, P2509.
- Checked 5-volt references, sensor grounds, PCM power, and grounds – all readings were correct.
Other OBD2 Codes + Test Results:
- P2262: Turbocharger boost not detected.
- P0471: Exhaust back pressure sensor 1.
- P0102: Mass air flow sensor A low.
- P1193: Inlet air temp sensor high.
- P2228: Baro pressure circuit low.
- P2229: Baro pressure sensor high.
- P2580: Turbocharger speed sensor low.
- P2509: ECM PCM Input signal intermittent.
Suggestions to Fix Issue:
- Consider the possibility of wiring issues or an internal fault in the ECU.
- Check for a shorted FPS if the engine was recently washed.
- Test PCM powers and grounds during cranking (starter disabled).
- Unplug all sensors mentioned in the codes and start the vehicle with them unplugged, then plug in one sensor at a time to narrow down the issue.
Final Fix:
- Replaced the PCM, resolving the issue. The truck has been functioning well since.
How to diagnose P2509
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Advice | Diagnostic Step |
|---|---|
| Replace Batteries | Test the batteries using an electronic tester and a carbon pile at varying temperatures and states of charge. |
| Check Power and Grounds to PCM | Thoroughly check all power and ground circuits on the vehicle for voltage drops. |
| Inspect Wiring Harness | Check the wiring harness for any signs of damage, corrosion, or loose connections. |
| Replace ECM/PCM | If batteries and wiring are in good condition, consider replacing the ECM/PCM. |
| Check Alternator Function | Test the alternator’s performance and output to ensure proper charging of the battery. |
| Reset PCM | Clear the diagnostic trouble codes and reset the PCM to see if the issue persists. |
| Inspect TIPM | Check the Totally Integrated Power Module for any issues or faults. |
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko