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OBD-II Diagnostic Trouble Code
C0265

Electronic Brake Control Module Relay Circuit

C
Chassis
brakes / steering
0
Generic
SAE standard
2
Chassis subsystem
65
Electronic Brake Control Module Relay Circuit
Severity · general guide
High
Brakes/steering — inspect soon
Code type
Chevrolet
System
Chassis
Quick answer

On General Motors vehicles C0265 means the electronic brake control module (EBCM) has detected a fault in its relay circuit — the internal relay that feeds high-current battery power to the ABS pump motor and solenoid valves. When it sets, the module switches off ABS, traction and stability control for that ignition cycle and lights the brake-system warnings, though normal (base) hydraulic braking still works.

Part of the generic C0265 overview — this page covers the Chevrolet meaning specifically.

What C0265 means

C0265 is a chassis (C-series) code, and because chassis codes are defined by each carmaker rather than by one global standard, its meaning is make-specific — this description applies to General Motors, where C0265 is the EBCM relay circuit fault. GM ABS units carry their relays inside the EBCM itself: a solenoid (valve) relay that is energized whenever the ignition is ON and supplies the solenoid valves, plus a pump-motor relay that completes the circuit to the ABS pump motor only when the module commands anti-lock, traction or stability action. Both relays are non-serviceable because they are integral to the module. The EBCM constantly watches this relay circuit — the switched battery feed, the relay contacts, and the ground path — and expects the voltage to change state when it commands the relay ON or OFF. C0265 sets when the module sees no response, a stuck or open relay, a loss of the high-current battery supply, or a bad ground on that circuit. Since the relay powers the hydraulic actuator, the module cannot trust ABS operation, so it disables ABS, traction control and StabiliTrak/electronic stability for the rest of the ignition cycle and turns on the associated warning lamps.

Symptoms

  • Amber ABS warning light stays on, usually alongside the traction-control and StabiliTrak/ESC indicators
  • A 'Service Brake System', 'Service Traction Control' or 'Service StabiliTrak' message appears in the driver information center
  • Anti-lock, traction and stability control are inoperative — the pedal no longer pulses on a hard or slippery stop
  • The red BRAKE warning may also illuminate on some GM models when ABS is disabled
  • Base braking still feels normal, but wheels can lock earlier during emergency or low-grip stops

Common causes

  • Failed or intermittent EBCM internal relay (solenoid or pump-motor relay) — the relay is built into the module and is not separately replaceable
  • Loss of the high-current battery (B+) feed to the EBCM: blown ABS maxi-fuse/fusible link or an open in the supply wire
  • Corroded, loose or backed-out terminals in the EBCM power/ground connector, giving high resistance on the feed or ground
  • Poor or open ground for the module/pump circuit at the body or frame ground point
  • Low system voltage — a weak battery or failing charging system dropping the feed below the roughly 10 V the module needs to run the test
  • Water intrusion or corrosion inside the EBCM or its harness connector after underbody exposure
  • A wiring short-to-ground on the relay control or power circuit

Diagnostic approach

  1. Confirm the code and read live data — Use a scan tool that decodes GM chassis codes and record C0265 as current or history, plus any companion codes such as a pump-motor circuit code (for example C0110/C0266). Note the freeze-frame battery voltage, since the module needs ignition voltage above about 10 V for the relay test to run.
  2. Check battery and charging voltage first — Measure battery voltage at rest and with the engine running. A weak battery or undercharging that pulls the EBCM feed below roughly 10 V can set C0265 without any relay fault, so correct any voltage problem before condemning the module.
  3. Verify the high-current battery feed to the EBCM — Inspect the ABS maxi-fuse or fusible link in the underhood fuse block and confirm battery voltage is present at the EBCM B+ terminal with the ignition ON. An open feed or blown fuse starves the internal relays and pump motor and will trigger the relay-circuit fault.
  4. Inspect grounds and the EBCM connector — Disconnect the EBCM harness connector and check for corrosion, water, spread or backed-out terminals, and pushed-back seals. Confirm a clean, low-resistance ground path for the module and pump circuit at the body/frame ground; high resistance on the ground can set C0265.
  5. Command the relay and pump-motor self-test — With the ignition ON and voltage healthy, run the scan tool's ABS pump-motor/relay actuation test and listen and feel for the pump and solenoids cycling ON and OFF. GM also runs a power-up self-test at ignition ON and again above about 15 km/h (9 mph) that commands these components; no response points to the internal relay circuit.
  6. Confirm the EBCM as the fault — If the battery feed, grounds, fuses and connector are all good and the code returns after clearing with the ignition ON, the internal relay is at fault. Because the solenoid and pump-motor relays are non-serviceable parts of the module, the repair is to replace the EBCM (or the EBCM/BPMV assembly) and, on many GM models, set it up or program it before re-verifying that C0265 stays clear.

FAQ

Can I still brake safely with a C0265 code?

Yes, your ordinary hydraulic brakes still work normally — pushing the pedal still stops the car. What you lose is the anti-lock, traction and stability functions, because the EBCM shuts them off when it can't trust the relay circuit. That means a wheel can lock up in a panic or low-grip stop, so brake earlier and more gently and keep extra following distance until it's repaired.

Is C0265 a relay I can just swap out?

No. On GM vehicles the ABS relays are built inside the electronic brake control module (EBCM) and are labeled non-serviceable, so there is no separate relay to replace. If the relay circuit itself has failed after the power feed, grounds, fuses and connector all check good, the fix is to replace the EBCM (often the combined EBCM and brake pressure modulator valve assembly).

Could a weak battery cause C0265?

It can. The EBCM only runs its relay test when the feed is above roughly 10 volts, and it needs a strong high-current supply to drive the pump motor. A weak battery, a failing alternator, or corroded power and ground connections can drop the voltage enough to set C0265 even though the module is fine, so always verify charging-system voltage and the ABS power feed before replacing anything.

Why did the traction control and StabiliTrak lights come on too?

Traction control and StabiliTrak rely on the same EBCM and the same pump motor and solenoids as ABS. When C0265 sets, the module disables all of those functions together for the rest of the ignition cycle, so their warning lights and any 'Service' messages come on at the same time as the ABS light. They should all clear once the relay-circuit fault is repaired.

Will C0265 clear by itself?

If the cause was a brief voltage dip, the code may go to history and the lights may go out on the next clean ignition cycle. But if the relay circuit, feed or ground has a real fault, it will reset and the ABS, traction and stability systems will stay off. Have the actual cause diagnosed rather than relying on it clearing on its own.