C1268

What Does Code C1268 Mean?

The diagnostic trouble code C1268, identified as “Motor Relay #1 Circuit Failure,” indicates that the Anti-lock Brake System (ABS) control module (which may also be integrated into a Vehicle Stability Control (VSC) or Electronic Stability Program (ESP) module, depending on the manufacturer) has detected an electrical anomaly within the circuit responsible for controlling or powering Motor Relay #1. This specific relay is almost universally dedicated to supplying high current to the ABS pump motor. The ABS module continuously monitors the voltage, current draw, or resistance across the control circuit (relay coil) and the power circuit (relay contacts) for this critical component. When the module detects an electrical fault such as an open circuit, a short to ground, a short to voltage, or an out-of-specification resistance value, it interprets this as a “circuit failure” and stores code C1268. This fault directly compromises the functionality of the ABS, VSC, and traction control systems, preventing their activation.

Common Symptoms

• ABS Warning Light Illuminated: The primary indicator, signaling a malfunction in the anti-lock braking system.
• Traction Control (TC) or Vehicle Stability Control (VSC/ESP) Warning Light Illuminated: Since these systems rely on the ABS pump, their warning lights will also typically activate.
• Loss of ABS Functionality: During hard braking, the wheels may lock up, and the characteristic ABS pulsation through the brake pedal will be absent.
• Potential Reduction in Braking Effectiveness: While base hydraulic braking remains, the absence of ABS can lead to longer stopping distances or loss of control during emergency braking on slippery surfaces.
• No Audible ABS Pump Motor Activation: The ABS pump motor will not engage during self-tests upon ignition or during an ABS event.

What Causes the Code C1268?

• Faulty ABS Pump Motor Relay #1: An internal failure of the relay coil (open circuit), stuck contacts, or worn out internal components preventing proper operation.
• Wiring Harness Issues: An open circuit (break in wire), short to ground, or short to voltage in the power supply wire to the relay, the control wire from the ABS module, or the output wire to the ABS pump motor. Corrosion at connectors is also a common culprit.
• Blown Fuse: The fuse supplying power to the ABS motor relay or the ABS pump motor itself may have blown due to an overcurrent condition.
• Faulty ABS Pump Motor: The motor itself could have an internal short, an open circuit in its windings, or be drawing excessive current, leading to relay failure or preventing proper operation.
• Corroded or Damaged Relay Socket: Poor electrical contact at the relay terminals due to corrosion, dirt, or damaged female pins in the fuse/relay box.
• Faulty ABS Control Module: Less common, but the internal driver circuit within the ABS module responsible for actuating the relay coil could be defective.

How to Diagnose and Troubleshoot

Diagnosis of C1268 requires careful electrical testing using a digital multimeter (DMM) and potentially a bi-directional scan tool. Always consult the vehicle-specific wiring diagrams and service manual for relay locations, pinouts, and specified values.

1. Visual Inspection: Begin with a thorough visual inspection of the ABS pump motor relay and its immediate wiring. Look for signs of corrosion, burnt connectors, damaged insulation, or loose terminals. Locate and inspect the relevant fuse(s) for the ABS pump motor and the ABS module. Replace any blown fuses, but be aware that a blown fuse often indicates an underlying short circuit.
2. Retrieve Freeze Frame Data: Use an OBD-II scanner to read freeze frame data associated with C1268. This data can provide valuable context (e.g., vehicle speed, engine load) about the conditions under which the fault was first detected. Clear the code and attempt to reproduce the fault after initial visual checks.
3. Identify and Test ABS Pump Motor Relay #1:
   • Locate the ABS pump motor relay using the service manual.
   • Relay Coil Resistance Check: With the relay removed, use a DMM to measure the resistance across the coil terminals (typically pins 85 and 86). Compare to manufacturer specifications; an open circuit (OL) or extremely high resistance indicates a faulty coil.
   • Relay Contact Continuity Check: With the relay de-energized, check for continuity between the normally open (NO) contacts (typically pins 30 and 87a or 87). There should be no continuity. Then, apply 12V to the coil terminals (85 and 86) to energize the relay. You should hear a click, and there should now be continuity between pins 30 and 87. No click or no continuity indicates a faulty relay.
4. Circuit Voltage and Continuity Checks (Relay Socket):
   • Power Supply to Relay (Pin 30): With the relay removed and the ignition ON, use a DMM to check for battery voltage (B+) at the relay socket terminal corresponding to pin 30. If no voltage, check upstream wiring and fuses.
   • Control Circuit Power/Ground (Pins 85 & 86):
     • Check for 12V at one coil terminal (e.g., 85) with ignition ON.
     • Check for good ground (continuity to chassis ground) at the other coil terminal (e.g., 86). The ABS module typically provides a switched ground to activate the relay. A bi-directional scan tool can be used to command the ABS pump motor ON/OFF to test this.
   • Output to Pump Motor (Pin 87): With the relay installed and commanded ON (e.g., via scan tool or by simulating conditions for self-test), verify 12V at the relay socket terminal corresponding to pin 87.
   • Continuity to ABS Pump Motor: With the relay removed and the ABS pump motor disconnected, check for continuity between the relay socket terminal 87 and the corresponding power input terminal at the ABS pump motor connector. Check for shorts to ground or voltage on this wire.
5. ABS Pump Motor Testing: If the relay and its circuits test good, the ABS pump motor itself may be at fault. Disconnect the motor’s electrical connector and measure its internal resistance across its power and ground terminals. Compare to manufacturer specifications. An open circuit (OL), short circuit (very low resistance), or excessively high resistance indicates an internal motor failure.

Recommended Repairs and Solutions

The repair strategy for C1268 is highly dependent on the diagnostic findings:

• Replace Faulty ABS Pump Motor Relay: If bench testing confirms the relay is defective, replacing it is the most straightforward solution. Ensure the replacement relay meets OEM specifications.
• Repair or Replace Damaged Wiring: If an open circuit, short to ground, or short to voltage is identified in the wiring harness, repair the damaged section using appropriate automotive-grade wiring, connectors, and heat-shrink tubing. Replace severely damaged sections of the harness as needed. Pay close attention to corroded terminals within connectors or the relay socket itself. Clean terminals thoroughly with electrical contact cleaner and apply dielectric grease to prevent future corrosion.
• Replace Blown Fuse and Investigate Cause: If a blown fuse is found, replace it with a fuse of the correct amperage. However, simply replacing the fuse without addressing the root cause (often an overcurrent draw from the pump motor or a short in the wiring) will likely result in the new fuse blowing again.
• Replace ABS Pump Motor/HCU Assembly: If the ABS pump motor itself is found to be internally shorted, open, or drawing excessive current, the entire ABS pump motor assembly (often integrated with the Hydraulic Control Unit, HCU) will require replacement. This can be a significant repair, and often requires specialized bleeding procedures and potentially module programming after installation.
• ABS Control Module Replacement: This should be considered a last resort. Only proceed with ABS module replacement after thoroughly testing and confirming that the relay, all associated wiring, fuses, and the ABS pump motor itself are functioning correctly. ABS module replacement often requires programming or calibration with a factory-level scan tool.

After any repair, clear the DTCs and perform a road test to verify the ABS system is fully functional and the C1268 code does not return. If applicable, perform an ABS system self-test or a component activation test using a bi-directional scan tool.