C1113

What Does Code C1113 Mean?

Diagnostic Trouble Code C1113 signifies a detected “ABS Power Relay Coil Short Circuit To Battery” within the vehicle’s Anti-lock Braking System (ABS). The ABS control module, often referred to as the Electronic Brake Control Module (EBCM) or integrated within the Powertrain Control Module (PCM) depending on the vehicle architecture, is responsible for monitoring the operational integrity of critical ABS components, including its primary power relay. This specific code is set when the control module detects a persistent voltage condition on the ABS power relay coil circuit that is inconsistent with its commanded state. Specifically, the module expects to control the activation and deactivation of the relay coil. If the module senses a direct short circuit to battery voltage (12V) on the coil circuit, indicating an unintended power supply or an internal fault causing constant energization regardless of the module’s output command, it interprets this as a malfunction. This condition prevents the ABS module from correctly controlling the power supply to the ABS hydraulic unit and pump motor, rendering the ABS system inoperative or causing abnormal operation, and potentially leading to parasitic battery drain due to the relay being constantly energized.

Common Symptoms

• ABS Warning Light Illumination: The most immediate and common indicator, signifying a fault within the Anti-lock Braking System.
• Traction Control System (TCS) Light Illumination: As TCS relies heavily on ABS components, this warning light will often accompany the ABS light.
• Vehicle Stability Control (VSC) Light Illumination: Similar to TCS, VSC systems integrate with ABS, and a fault in the ABS will typically disable VSC.
• Inoperative ABS Function: The vehicle’s brakes will function as conventional brakes, but without the anti-lock feature during hard braking, potentially leading to wheel lock-up.
• Unusual Brake Pedal Feel: In some cases, if the relay is stuck energized or fluctuating, a slight pulsation or unusual feel may be present at the brake pedal.
• Parasitic Battery Drain: A direct short to battery voltage can cause the ABS power relay coil to remain energized even when the vehicle is off, leading to a gradual discharge of the battery over time.

What Causes the Code C1113?

• Damaged Wiring Harness: A chafed, cut, or otherwise compromised wire in the ABS power relay coil control circuit that is making direct contact with a constant 12V power source (short to battery voltage). This is a highly frequent cause.
• Faulty ABS Power Relay: An internal short circuit within the relay itself, where the relay coil’s windings are compromised or its internal contacts are fused/shorted, leading to constant energization or an incorrect resistance reading.
• Corroded Relay Socket or Connector Pins: Water intrusion or severe corrosion within the ABS relay socket or the main ABS module connector can create an unintended bridge between the relay coil control circuit and a constant battery positive voltage pin.
• Internal ABS Control Module (EBCM) Fault: Less common, but a failure within the ABS module’s internal driver circuit responsible for controlling the ABS relay coil can cause a continuous 12V output, leading to the short-to-battery condition.

How to Diagnose and Troubleshoot

Diagnosing C1113 requires methodical electrical troubleshooting:

1. Visual Inspection: Begin by performing a thorough visual inspection of the entire ABS system. Focus on the ABS module, its wiring harness, the ABS power relay, and its associated connectors. Look for signs of physical damage, chafing, corrosion, melted insulation, or any aftermarket modifications that might affect the wiring. Pay particular attention to wiring that passes through firewall grommets, under the battery tray, or near exhaust components, as these are common areas for damage.
2. OBD-II Scan and Freeze Frame Data: Connect a professional-grade OBD-II scanner capable of communicating with the ABS module. Confirm the presence of C1113 and check for any related or accompanying codes. Review freeze frame data, if available, to understand the operating conditions (engine RPM, vehicle speed, etc.) when the code was set.
3. ABS Power Relay Test:
   • Locate and carefully remove the ABS power relay from its socket.
   • Using a Digital Multimeter (DMM), measure the resistance across the relay’s coil terminals (typically pins 85 and 86 on a Bosch-style relay). Compare this reading to the manufacturer’s specifications, which are usually in the range of 60-120 ohms. An open circuit (infinite resistance) or an extremely low resistance (near 0 ohms) indicates an internal fault within the relay coil itself.
   • To test the relay’s switching function, apply fused 12V and ground to the coil terminals. You should hear an audible click. Then, use the DMM to check for continuity across the switch terminals (typically pins 30 and 87/87a). Continuity should be present when energized and open when de-energized (for 87) or vice-versa (for 87a).
4. ABS Relay Socket Voltage Test:
   • With the ABS relay removed and the ignition OFF, use a DMM to measure voltage at the ABS relay socket. Specifically, identify the pin that supplies power to the relay coil when the module commands it ON (this is often the control side from the module, not the constant 12V supply to the relay’s power contacts).
   • There should be no voltage present on this control pin with the ignition OFF and the module not commanding the relay ON. If 12V is consistently present, it indicates a short to battery voltage in the wiring harness or an internal fault within the ABS module.
5. Wiring Harness Integrity Check:
   • Disconnect the electrical connector from the ABS control module and the ABS power relay.
   • Identify the wire corresponding to the ABS power relay coil control circuit (the wire that runs from the ABS module to the relay coil terminal).
   • Using a DMM, check for continuity between this isolated wire and a known constant 12V source (e.g., the battery positive terminal or a fused 12V bus). There should be infinite resistance (open circuit). If continuity exists, trace the wiring to locate and repair the short.
   • Additionally, check this wire for continuity to chassis ground. While C1113 specifies a short to battery, a compromised wire could short to ground, causing other issues.
6. ABS Module Power and Ground Verification: Before condemning the ABS module, ensure that all its power and ground supply circuits are robust. Check for proper voltage on all fused power inputs and verify low resistance to chassis ground on all ground circuits at the ABS module connector with the DMM.

Recommended Repairs and Solutions

The resolution for C1113 typically involves addressing the specific electrical fault identified during diagnosis:

• Repair or Replace Damaged Wiring: If the diagnosis points to a short circuit in the wiring harness supplying the ABS power relay coil, the primary repair involves tracing and locating the exact point of damage. Repair the damaged section using appropriate automotive-grade wire, heat-shrink tubing, and waterproof connectors to ensure a durable and reliable repair. Avoid temporary fixes like electrical tape.
• Replace Faulty ABS Power Relay: If the ABS power relay itself is found to have an internal short in its coil or is sticking, it must be replaced. Always use a genuine OEM replacement relay or a high-quality aftermarket equivalent that matches the original specifications for current rating and pin configuration.
• Clean or Replace Corroded Connectors: If corrosion is found in the relay socket or the ABS module connector, carefully clean the affected pins using electrical contact cleaner and a small wire brush. If the corrosion is severe or has caused damage to the terminals, it may be necessary to replace the connector shell or individual pigtail terminals to ensure proper electrical contact. Apply dielectric grease upon reassembly to prevent future corrosion.
• Replace ABS Control Module (EBCM): If all wiring, relays, and power/ground supplies to the module have been thoroughly tested and confirmed to be in perfect working order, and the short-to-battery condition is confirmed to be originating from an internal fault within the ABS module’s output driver for the relay coil, then the ABS control module will require replacement or specialized repair. Be aware that replacing an ABS module often necessitates specific programming, calibration, or “bleed” procedures using a compatible diagnostic scanner after installation.
• Post-Repair Verification: After completing any repair, clear the C1113 code and any other related codes from the ABS module memory using an OBD-II scanner. Perform a test drive, ensuring the ABS system activates and deactivates correctly during controlled braking maneuvers. Re-scan the system to confirm that the code does not return.