P0615 Code Symptoms, Causes, Diagnosis and Repair Cost Overview

Introduction

Drivers who turn the key or press the start button and hear nothing but a click—or hear nothing at all—are likely confronting a P0615 code. The fault indicates a malfunction in the “Starter Relay A Circuit,” a pathway that the PCM/ECM uses to energize the starter relay. When that circuit fails, the starter motor never receives the command to spin, producing a dead‑battery‑like sensation even though the battery may be fully charged. The check‑engine light (MIL) usually flashes or stays on, confirming that the vehicle’s computer has logged the fault. Early identification prevents repeated attempts to start the engine, which can drain the battery and mask other emerging issues.

Symptoms

• No‑crank condition – engine does not turn over despite a normal‑looking battery voltage.
• Intermittent cranking – occasional successful starts followed by repeated failures.
• Clicking noise – relay clicks without the starter motor engaging.
• MIL illumination – check‑engine light appears or flashes, often accompanied by a stored P0615 code.
• Battery‑like voltage drop – voltage at the starter terminal falls dramatically when the start button is pressed, mimicking a dead battery.

These signs point directly to a breakdown in the starter‑relay control circuit rather than a fuel‑system or ignition‑coil problem.

Why This Happens

Faulty Starter Relay A

The relay contains a coil that, when energized by the PCM, closes contacts to feed high current to the starter motor. Internal coil burnout, contact welding, or mechanical sticking prevents the relay from closing, leaving the starter silent.

Damaged Wiring or Connectors

Corrosion, chafing, or broken pins in the harness that runs between the PCM, relay, and battery can interrupt the low‑current control signal or the high‑current power feed. A single open circuit will stop the relay from receiving voltage.

PCM/ECM Control‑Circuit Failure

The PCM outputs a 5 V or 12 V control signal to the relay. A failed output driver, software glitch, or internal short within the PCM can keep the signal permanently low, causing the P0615 code.

Poor Ground or Voltage Supply

The starter relay and PCM share a common ground. A loose or corroded ground strap creates a voltage drop that the PCM interprets as a circuit fault, triggering the code even if the relay itself is functional.

Battery or Voltage‑Regulation Issues (Secondary)

While the battery is rarely the root cause, an excessively low system voltage can prevent the PCM from generating a sufficient control signal. In such cases, the primary focus remains on the relay circuit rather than the battery itself.

Diagnostic and Repair Procedures

1. Scan and Verify – Connect a professional OBD‑II scanner, read the P0615 code, and note any related codes (e.g., P0616, P0617). Clear the code and attempt a start to see if it returns.
2. Visual Inspection – Locate Starter Relay A (usually in the engine‑compartment fuse/relay box). Check for burnt terminals, loose pins, or water intrusion.
3. Power/Ground Test – With the ignition on, measure voltage at the relay’s control‑circuit terminal. You should see 5 V–12 V when the start button is pressed. Measure ground continuity to the chassis; resistance should be <0.1 Ω.
4. Relay Actuation Test – Using a 12 V jump source, apply voltage directly to the relay coil terminal. If the relay clicks and the starter engages, the relay is good; if not, replace it ($20‑$50 plus $80‑$120 labor).
5. PCM Output Test – If the control voltage is absent, probe the PCM output driver with a back‑probe while the start command is issued. No voltage indicates a PCM fault.
6. Wiring Continuity Check – Use a multimeter to verify continuity from the PCM to the relay and from the relay to the starter motor. Repair any broken wires or corroded connectors ($50‑$150 for wiring repair).
7. Re‑program PCM (if applicable) – Some manufacturers require a software update to clear false P0615 entries after a repair. Re‑programming typically costs $150‑$250.
8. Replace PCM/ECM (if necessary) – When the PCM output driver is confirmed defective, replacement is the most reliable solution. Replacement units vary by production date and software version; the correct module is matched by VIN before programming. Expect $600‑$900 for the part plus $200‑$300 labor.

All repairs should be performed with the battery disconnected and the vehicle in park/neutral with the parking brake engaged.

When Replacement Makes Sense

If the PCM’s control driver has failed, repairing the board is often a temporary fix because the underlying silicon damage can re‑manifest under normal thermal cycles. Replacing the PCM eliminates the risk of recurring P0615 codes and restores full system integrity.

Modern control modules are complex and integrated with security and immobilizer systems. That’s why choosing a replacement isn’t only about the hardware—it’s about correct programming and compatibility. Flagship One specializes in VIN‑matched control modules, providing a plug‑and‑drive solution backed by warranty. Their modules arrive pre‑programmed to your vehicle’s specifications, ensuring seamless integration and eliminating dealer‑only re‑coding delays.

Preventive Maintenance

• Keep relay box dry – Seal the engine‑compartment fuse/relay box and inspect the gasket regularly.
• Inspect wiring harnesses – Look for signs of abrasion, chafing, or corrosion at connector boots, especially near the starter motor and PCM.
• Maintain battery health – A healthy battery supplies stable voltage to the PCM; keep terminals clean and tightened.
• Periodic scans – Even if the vehicle runs well, a quarterly OBD‑II scan can catch early‑stage P0615‑related anomalies before they cause a no‑crank event.
• Secure grounds – Verify that all ground straps to the chassis and engine block are tight and free of rust.

Following these steps reduces the likelihood of a starter‑relay circuit fault and helps the PCM operate within its designed parameters.