GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Tahoe - 2WD 🢒 Brakes 🢒 Antilock Brake System 🢒 Self-Diagnostics

The electronic brake control module (EBCM) performs self-diagnostics of the ABS. The EBCM detects and isolates system malfunctions. When a malfunction is detected, the EBCM sets a corresponding diagnostic trouble code (DTC).

Malfunction Response

ABS response to malfunctions falls into four classes:

    • Permanent Latched Malfunction Response: This means that the ABS is disabled and the ANTILOCK indicator lamp is requested on (whenever the ignition is turned on) even if the cause of the malfunction goes away. This malfunction can not be cleared with a scan tool. The EBCM must be replaced and the module must be returned to the manufacturer.
    • Ignition Latched Malfunction Response: This means that the ABS is disabled and the ANTILOCK indicator lamp is requested on until the ignition is turned off even if the cause of the malfunction goes away. When the ignition is turned on again, the ABS will not be disabled unless/until a subsequent malfunction is detected.
    • Condition Latched Malfunction Response: This means that the ABS is disabled and the ANTILOCK indicator lamp is requested on only as long as the apparent malfunction condition persists. Normal ABS operation resumes automatically and the ANTILOCK indicator is requested off as soon as the problem goes away; no service is necesary. The vehicle operator may choose, without being prompted further by the ANTILOCK indicator lamp, to take the vehicle to an authorized service center.
    • Information Only Malfunction Response: This means that the ABS is not disabled and no indicator lamp is requested for this malfunction. ABS activity continues as it was before this malfunction occured.
    • DRP Critical Malfunction Response: This means that the DRP system is disabled and the BRAKE indicator lamp is requested on. The DRP malfunction is latched the same as the ABS one is for a given malfunction (Permanent, Ignition, and Condition latched), i.e. a malfunction that is Ignition Latched for ABS activity is also ignition latched for DRP activity.
    • DRP Non-Critical Malfunction Response: This means that if more than one of these malfunctions are detected, then DRP is disabled and the BRAKE indicator lamp is requested on. The DRP malfunction is latched the same as the ABS one is for a given malfunction (Permanent, Ignition, and Condition latched), i.e. a malfunction that is Ignition Latched for ABS activity is also ignition latched for DRP activity. All Keep Alive malfunctions are counted separately for purposes of DRP Keep Alive except for sensor malfunctions. All the sensor malfunctions for a particular wheel are counted as a single Keep Alive malfunction, i.e. a DTC C0221 and C0222 are considered one Keep Alive malfunction.
    • Information Only Malfunction Response: This means that the DRP is not disabled and no indicator lamp is requested for this malfunction. DRP activity continues as it was before this malfunction occurred.