25823996 | Genuine GM® Anti-Lock Brake Control Module

An Anti-Lock Brake Control Module 25823996 (also called ABS Control Module, ABS Module, or ABS ECU) is the computer that controls the anti-lock braking system in a vehicle. It is the main electronic part that decides when and how the ABS should activate to keep the wheels from locking during braking.

General Specifications

Fitment

GMC Kodiak/Topkick 2003-2009
Chevrolet T6500, T7500, 2004-2009  
GMC C4500, GMC, C6500, C7500 2003-2009

Purpose & Function (88935852)

1. Prevent Wheel Lock-Up

The module monitors wheel speeds and prevents them from locking when you brake hard.
This helps avoid:

• Skidding

• Sliding

• Loss of control

2. Maintain Steering Control While Braking

• If wheels lock, you cannot steer.
• The ABS Control Module keeps the wheels rotating just enough so you can turn the vehicle while braking.

3. Improve Vehicle Stability

By rapidly adjusting brake pressure, the module helps the vehicle stay balanced and prevents sideways sliding, especially on:

• Wet roads

• Ice or snow

• Gravel or dirt

• Abrupt stops

4. Control the ABS Pump and Valves

The module commands the hydraulic unit to:

• Reduce brake pressure

• Reapply pressure

• Pulse the brakes many times per second

This happens automatically and much faster than a human could do.

5. Run Diagnostic Checks

The module constantly checks:

• Wheel speed sensors

• ABS pump

• Hydraulic valves

• Internal circuits

If it detects a problem, it turns on the ABS warning light.

6. Work With Other Safety Systems

The ABS Control Module often shares data and works together with:

• Traction Control System (TCS)

• Electronic Stability Control (ESC/ESP)

• Brake Assist

• Hill-Start Assist systems

These systems rely on the module to help keep the vehicle safe.

Signs of Bad Anti-Lock Brake Control Module

1. ABS Warning Light Stays On

• The dashboard ABS light (sometimes with traction control light) turns on and stays on.

• Indicates the module has detected a problem or lost communication with sensors.

2. ABS Doesn’t Activate

• During hard braking, the pedal doesn’t pulse.

• You may hear no ABS pump noise.

• Wheels can lock up, especially on slippery surfaces.

3. Brakes Lock Up or Skid

• Without proper control from the module, the ABS cannot modulate brake pressure.

• Wheels may lock during braking, increasing the risk of losing steering control.

4. Brake Pedal Problems

• Pedal may feel hard, soft, or spongy.

• Brakes may respond inconsistently.

5. Traction Control or Stability Control Lights On

• Systems like TCS or ESC often rely on the ABS module.

• A failing module can trigger multiple warning lights.

6. Erratic ABS Behavior

• ABS may engage randomly without heavy braking.

• Pulsing or vibration in the brake pedal at normal speeds.

• Strange buzzing or grinding noises from the brake system.

7. Speedometer or Wheel Data Issues (in some vehicles)

• If the module provides wheel speed data, you may see speedometer jumping or inaccurate readings.

8. Diagnostic Trouble Codes (DTCs)

• Scan tools may show ABS module-related errors:

  • Communication failures

  • Sensor circuit failures

  • Pump or valve errors

About GM

General Motors (GM) is one of the largest and most iconic automotive manufacturers in the world. Founded in 1908 and headquartered in Detroit, Michigan, GM designs, builds, and sells vehicles under several well-known brands, including Chevrolet, GMC, Cadillac, and Buick.
GM is known for its long history of innovation in the automotive industry, from developing early electric vehicles to advancing autonomous driving and connected car technologies. The company has a strong global presence and is committed to a future of zero crashes, zero emissions, and zero congestion, with significant investments in electric vehicles (EVs) and sustainable mobility.