The OBD2 code P0615 indicates a malfunction within the starter relay control circuit, which is crucial for the ignition process in vehicles. This circuit’s responsibility is to manage the electrical connection that triggers the starter motor, enabling the engine to turn over and begin running. When issues arise within this circuit, it may lead to the vehicle experiencing starting problems, ranging from intermittent failures to complete inability to start.
P0615 quick overview
| Meaning | P0615: Starter Relay Control Circuit |
| Is it serious? | Yes, as it can prevent the engine from starting or cause intermittent start issues. |
| Possible causes | – Faulty or damaged starter relay – Issues within the wiring or connectors leading to the starter relay – Malfunctions in the engine control module (ECM) affecting relay control – Poor ground connections |
| How to diagnose? | Inspect the starter relay and its connections for any signs of damage or corrosion Check the wiring leading to and from the starter relay for shorts, opens, or damage Test the starter relay with a multimeter to ensure proper function Examine the ECM outputs to the starter relay for any anomalies Verify ground connections related to the starter circuit for integrity |
P0615 Meaning
For those not familiar with car mechanics, think of the starter relay like a switch that connects your car’s battery to the starter motor, which in turn cranks the engine to life. The P0615 code popping up means there’s a hiccup in this switch’s operation, either because the switch itself is faulty, the wiring is damaged, or there’s an issue with the car’s computer that tells the switch when to activate.
It’s similar to having a broken light switch in your home; no matter how often you flip it, if the connection isn’t working correctly, the light won’t turn on. Fixing this issue ensures your vehicle can reliably start whenever you turn the key or press the start button.
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How to fix P0615 – learn from mechanics
I looked into P0615 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: Chevrolet
Vehicle Information 2012 Chevrolet Equinox LT 2.4L
Issue + Repair History
- Car is wrecked with numerous harness repairs.
- Symptoms indicate no output from PCM to activate starter relay.
- Crank request from BCM is present, but no starter relay activation.
- No immobilizer issues found.
- No injector pulse, indicating potential immobilization, but no related codes or PIDs.
Other OBD2 Codes + Test Results
- P0615: Starter relay control circuit
Mechanic Suggestions
- Check power inputs to ECM and verify Starter Request YES and Starter relay ON in data list.
- Monitor BCM Ignition Modes to verify crank request; if all checks pass, PCM likely at fault.
- Be cautious of crossed wires in harness due to previous repairs; perform pin-out test before PCM replacement.
- Verify if PCM scan indicates fuel enabled to confirm immobilization status.
- Check warranty status of PCM before replacement; it may be covered under an 80,000-mile warranty.
Final Fix
- Discovered broken green wire, potentially low-speed LAN, which, after repair, resolved most issues but still couldn’t crank with key.
- Powered wire from ECM to starter relay manually, which allowed vehicle to crank, start, and run fine.
- Planned next step: install new PCM, possibly with just J2534 pass through.
Case #2: Jeep
Vehicle Information 2006 Jeep Grand Cherokee Limited 5.7L
Issue + Repair History
- Intermittent start issue.
- Fault code P0615: Starter relay circuit fault.
- Lost ground to pin 85 from the ECU.
- Grounding pin 85 engages starter.
- Wire color: dark green with orange trace.
- No continuity found in wire going to ECU’s pin 44.
- ECU does not have pin 44.
- Gear shift live data shows correct positioning, discounting gear range sensor.
Other OBD2 Codes + Test Results
- P0615: Starter relay circuit fault
Mechanic Suggestions
- For diesel engines, ground is typically at pin 44 of the PCM, while for gas engines, it should come from pin 38 in C3 at the PCM.
- Ensure security system recognizes key to enable starting.
- Check fuse for security system (Fuse 20 10A in junction block).
Final Fix
- Discovered low voltage from starter circuit on ignition switch to ECU.
- Applying 12 volts to this circuit allowed starter to work and engine to start.
- Ordered and installed new ignition switch, resolving the issue.
- Confirmed fixed after replacing the ignition switch.
Case #3: GMC
Vehicle Information 2012 GMC Acadia SL 3.6L
Issue + Repair History
- Intermittent start issue.
- Scanned code P0615: starter relay circuit fault.
- Additional codes for airbags, air condition, and wheel speed sensors.
- P0615 code persists even before attempting to crank.
- Jumpering the relay allows cranking and starting.
- Energizing pin from the computer at the relay engages starter continuously.
- No theft codes detected.
- Battery voltage tested at 12V.
Other OBD2 Codes + Test Results
- P0615: Starter relay circuit fault
Mechanic Suggestions
- Disconnect Mass Air Flow (MAF) Sensor and check voltage on the Black/White wire at pin C.
- If voltage is greater than 0.05 volts, clean and verify a good ground at ground G110.
- Pinpoint the control wire by backprobing at the module connector.
- Investigate potential water ingress in the fuse box on the passenger side near the glove box.
- Disconnect the Purple wire at the starter solenoid, then jumper from B+ to that terminal on the solenoid to check starter engagement.
- Perform volt drop testing while cranking and inspect the right-hand IP fuse block for corrosion.
Final Fix
- Replaced the starter due to excessive shaft play.
- Modified the purple wire with a push button for customer satisfaction.
How to diagnose P0615
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.
| Diagnostic Step | Explanation |
|---|---|
| Inspect the starter relay | Check for physical damage, corrosion, or signs of wear. |
| Check the wiring | Look for damaged, frayed, or corroded wires and connectors. |
| Test the starter relay | Use a multimeter to verify the relay’s functionality. |
| Examine the ECM outputs | Ensure the ECM is properly sending signals to engage the relay. |
| Verify ground connections | Check all ground points related to the starter circuit for solid connections. |
Addressing a P0615 code involves a thorough examination of the starter relay system, from the relay itself to the wiring and control mechanisms. Given the critical role of this circuit in starting the vehicle, resolving this issue promptly is essential for reliable vehicle operation. Professional diagnostics and repairs are recommended to accurately identify and correct the underlying problem, ensuring the vehicle starts smoothly and reliably.
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