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C0252 Code Explained: Causes, Symptoms & Electronic Brake Control Module Motor Relay Circuit Fixes

An OBD-II scanner displaying C0252 with the ABS hydraulic control unit and pump motor relay highlighted inside the engine compartment fuse box while the ABS and traction control warning lights are illuminated.

If your scan tool displays C0252, your vehicle’s Electronic Brake Control Module (EBCM) has detected a malfunction within the ABS pump motor relay circuit.

The ABS pump motor requires a high-current electrical relay to operate. During an anti-lock braking event, the EBCM energizes the motor relay, allowing battery voltage to power the hydraulic pump. The pump rapidly restores brake pressure while the ABS valves cycle pressure to each wheel, helping maintain steering control under hard braking.

When the EBCM detects an open circuit, short circuit, excessive resistance, or relay performance issue, it stores C0252 and typically disables the ABS, Traction Control, and Electronic Stability Control (ESC/StabiliTrak) systems.

For additional chassis diagnostics and repair guides, visit our Complete OBD-II Trouble Code Guide:

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Quick Facts

ItemInformation
OBD-II CodeC0252
DescriptionElectronic Brake Control Module Motor Relay Circuit
CategoryChassis (C) Codes
SystemAnti-lock Braking System (ABS)
Severity★★★★☆ High
Safe to Drive?Yes, but ABS and stability systems may be disabled
Common CausesFailed ABS relay, faulty EBCM, damaged wiring, blown fuse, low battery voltage
Typical Repair Cost$75–1,800

What Does C0252 Mean?

The C0252 code indicates the Electronic Brake Control Module has detected an abnormal condition within the ABS pump motor relay circuit.

The relay functions as a high-current electrical switch that supplies battery voltage to the ABS hydraulic pump motor whenever the system needs to rapidly restore brake pressure during ABS operation.

If the EBCM detects:

it stores C0252 and disables ABS operation to protect the braking system.

Unlike C0110, which usually points toward the pump motor itself, C0252 specifically targets the relay control circuit.

Symptoms of C0252

Common symptoms include:

Normal hydraulic braking remains available.

Common Causes

Failed ABS Pump Relay

The relay contacts may become:

This is one of the most common causes.

Blown ABS Fuse

A blown high-current fuse supplying the relay or pump motor can immediately trigger C0252.

Damaged Wiring

Inspect for:

Faulty Electronic Brake Control Module

Internal relay drivers within the EBCM may fail, preventing proper relay operation.

Low Battery Voltage

Weak batteries and poor charging systems can prevent the relay from operating consistently.

Corroded Ground Connection

High-current ground circuits are critical for reliable ABS pump operation.

Poor grounds often cause intermittent relay faults.

How Serious Is C0252?

High.

The vehicle generally remains safe to drive under normal conditions, but the following systems are usually disabled:

Emergency braking performance may be reduced, especially on wet, snowy, or icy roads.

Can You Drive With C0252?

Yes—but use caution.

Without ABS:

Repairs should be completed as soon as practical.

How to Diagnose C0252

1. Scan the ABS Module

Use a professional scan tool capable of reading manufacturer-specific ABS codes.

Check for related faults such as:

2. Check Battery Voltage

Verify:

Low system voltage frequently contributes to relay faults.

3. Inspect the ABS Fuse

Inspect:

Replace any blown fuses only after determining why they failed.

4. Test the Relay

Using a multimeter or relay tester:

Verify:

Many relays can also be swapped with an identical relay for testing.

5. Inspect Wiring

Check:

Look for heat damage or corrosion.

6. Perform an Active Pump Test

Many professional scan tools can command the ABS pump motor on.

Verify:

Failure during the active test helps isolate the relay from the pump motor itself.

Common Repairs

RepairEstimated Cost
Replace ABS relay$40–120
Replace ABS fuse$20–50
Repair wiring$100–300
Clean ground connections$50–150
Replace Electronic Brake Control Module$800–1,800
Replace hydraulic control unit$700–1,600

Common Diagnostic Mistakes

Technicians commonly:

Vehicles Commonly Affected

C0252 is commonly found on:

GM vehicles equipped with StabiliTrak commonly report C0252, although similar relay-related ABS codes are found on other manufacturers.

How to Prevent C0252

Reduce the likelihood of C0252 by:

Frequently Asked Questions

What causes C0252?

The most common causes include a failed ABS relay, blown fuse, damaged wiring, faulty Electronic Brake Control Module, low battery voltage, or poor electrical connections.

Is C0252 dangerous?

While normal braking remains available, the loss of ABS and stability control reduces braking performance during emergency situations.

Can a bad relay cause C0252?

Yes.

A worn or stuck ABS pump motor relay is one of the leading causes of this code.

Will C0252 clear itself?

No.

The underlying electrical fault must be repaired before the ABS module clears the code.

Does C0252 affect engine performance?

No.

The code only affects braking and chassis control systems.

Final Thoughts

The C0252 code indicates a malfunction within the Electronic Brake Control Module motor relay circuit, preventing the ABS hydraulic pump from operating correctly during emergency braking. Although the vehicle usually remains drivable, the loss of ABS, traction control, and stability control significantly reduces braking safety on low-traction surfaces.

Most repairs involve replacing a faulty relay, repairing damaged wiring, correcting power or ground issues, or diagnosing the EBCM. A thorough electrical inspection should always be performed before replacing expensive ABS components.

For additional chassis diagnostics and repair guides, browse our complete Chassis (C) OBD-II Code Library:

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